The Great Belt Bridge has, in 2025, implemented a new inspection and maintenance strategy for the 254 m tall concrete pylons and the concrete anchor blocks. Ensuring the long‑term performance and safety of large suspension bridges requires reliable, repeatable, and efficient inspection methods. Traditional techniques ‑ such as rope access or lift‑based inspections ‑ pose safety risks, incur significant operational costs, and offer limited repeatability for tracking defect progression over time. This study presents an integrated digital inspection framework combining drone‑based imaging, high‑resolution 3D modelling, and AI‑driven defect detection to evaluate the condition of concrete pylons and anchor blocks on a major suspension bridge.

Aerial data were collected using unmanned aerial systems to capture detailed photographic coverage of the structures. High‑res textured 3D models were generated for two distinct inspection periods 2017 and 2025. These models enabled a Virtual Inspection workflow, allowing engineers to assess surface conditions remotely with high accuracy. AI algorithms were applied to automatically identify and classify defects such as cracking, spalling, delamination and corrosion. By comparing the 2017 and 2025 models, it was possible to quantify changes in defect dimensions, severity, and spatial distribution. The Health Certificate for the concrete elements, provided a standardized and repeatable method for tracking deterioration trends and supporting long‑term maintenance planning.

The digital inspection approach demonstrated significant advantages: improved inspector safety, reduced need for physical access infrastructure, minimized environmental footprint, and enhanced accuracy and consistency of defect evaluation. Furthermore, the ability to revisit digital twins facilitates more transparent, data‑driven decision‑making for asset management. The 3D models will be used as reference points for all future OM utilizing the ongoing developments within AI.

This paper outlines the methodology, presents key findings from the comparative analysis, and discusses how digital inspection and AI technologies can transform maintenance strategies for large‑scale bridge infrastructure with significant future benefits.

Ice shedding from bridge cables and pylons poses significant safety risks to traffic and infrastructure, making reliable detection and tracking of falling events essential for early warning systems in long‑span bridges. LiDAR sensors have been widely adopted in outdoor monitoring due to their capability to provide accurate three‑dimensional spatial measurements under diverse environmental conditions. However, LiDAR‑based detection and tracking frameworks specifically tailored to ice‑shedding scenarios remain limited, particularly in handling sparse point clouds and complex structural environments associated with falling events.

To address this gap, this study proposes a LiDAR‑based ice‑shedding detection and tracking framework. A voxel‑grid‑based background modeling strategy is first applied to suppress static structures. The remaining foreground points are projected onto a two‑dimensional plane parallel to the background surface, rather than performing direct association in the three‑dimensional point‑cloud space. To mitigate overlapping and mismatching in the projected domain, depth‑wise partitioning is conducted along the direction orthogonal to the background plane before trajectory association. Tracking is then performed in the projected space using a framework based on ThrowSORT, originally developed for falling‑object tracking. Finally, falling events are identified based on trajectory continuity and motion constraints established in our previous ice‑shedding studies.

The proposed framework was validated through controlled laboratory drop experiments and wind tunnel cable‑icing tests. Experimental results demonstrate reliable detection performance and reduced false alarms compared with conventional approaches. These findings indicate that LiDAR‑based monitoring provides a feasible and robust solution for ice‑shedding detection and may support risk mitigation and safety management of long‑span bridge infrastructure.

Internal inspections of bridge box girders are essential for ensuring structural integrity, yet their automation remains challenging in confined, low‑light, and GNSS‑denied environments. This study presents a field application of vision‑based inspection on the top slab inside the box girder of the Dunbyeong Bridge. High‑resolution images were manually acquired using digital cameras under low‑light conditions, with a ground sampling distance (GSD) of 0.2 mm/pixel. In the absence of GNSS signals, target‑based photogrammetry was used to establish local spatial control, and a 3D model of the inspected area was generated. A commercial AI‑based crack detection system was then applied to the acquired images. Under the tested conditions, most cracks with widths of 0.2 mm or greater were detected in the acquired images; however, false negatives and occasional false positives were observed in areas affected by severe image noise or inadequate lighting. These results indicate that vision‑based imaging can support detailed inspection and 3D reconstruction inside bridge box girders, while the performance of AI‑based crack detection remains sensitive to image quality in low‑light environments. The findings highlight the importance of stable localized lighting and image quality enhancement for more reliable automated internal bridge inspection.

This paper describes the findings from a continuous monitoring campaign where the vision‑based system was used to gather data on wind‑induced displacements of the longest hangers of the Great Belt Suspension Bridge. The monitoring outcome provided information on dynamic behavior of the hangers and informed next steps with respect to the fatigue management. The camera‑based system allowed high‑precision measurements (approx. 1 mm precision from 100 m) and enabled visual data verification of the results. Data (in mm) directly obtained from the system are much easier to interpret (no complex signal processing) than traditional bridge monitoring methods (e.g., accelerometers). Vision‑based system was integrated with the overall bridge asset management platform and the monitoring results were used by the bridge owner to extend service life (better estimation of the fatigue life) and avoid unnecessary and costly strengthening. The system also allowed for automatic saving and previewing of videos when the predefined displacement or vibration thresholds (in mm) were exceeded. The vision‑based system allowed multipoint measurements; however, image quality can be affected by weather. Vision‑based techniques can be deployed on other long‑span cable‑supported bridges, enabling real‑time evaluation of the dynamic monitoring data and cost‑efficient identification of problems in hanger functioning. To the authors knowledge, this is one of the first study to use the computer vision technique for continuous monitoring of suspension bridge hangers.

The Mackinac Bridge over the Straits of Mackinac was designed by Dr. David Steinman connects Michigan’s Upper and Lower Peninsulas. Opened in 1957, it is often referred to as the jewel of Michigan’s transportation system. The nearly five‑mile‑long crossing features a 7,400‑foot suspended span, 9,300 feet of truss spans, and 1,100 feet of viaduct spans that carry four lanes of Interstate 75 traffic. Most of the bridge structure, dates back to original construction, reflecting the effectiveness of the Mackinac Bridge Authority’s (MBA) maintenance program.

In August 2020, the MBA retained Parsons to conduct a comprehensive bridge deck study to determine the decks remaining service life, recommend rehabilitation and replacement strategies, and support capital improvement planning. The study concluded in 2022, and initial implementation has begun.

Working closely with the MBA, Parsons implemented a three‑phase plan. First, the team completed an in‑depth condition investigation of the existing deck and floor system. Using this data, they assessed the remaining service life of the current deck. Finally, they developed constructible deck replacement alternatives using client specific criteria compatible with the suspended, truss, and girder viaduct spans, emphasizing modern lane widths and improved safety features. For the suspended spans, aeroelastic bridge characteristics of the existing structure were evaluated to understand performance and the suitability of alternatives, including bridge section model testing.

The study found that over nearly 70 years the MBA has effectively preserved most of the original deck and floor system and, with a focused preservation strategy, can further extend the life of existing systems. The route carried by the bridge is an economic lifeline for the region and has no practical detours, which makes it essential that rehabilitation and replacement solutions allow the corridor to remain open to traffic.

For a tolled agency, deliberate planning is especially important. Extending service life through targeted preservation reduces the frequency and magnitude of future capital projects and supports predictable toll revenues. Coordinated phasing of work limits overlapping contracts, minimizes user delays, and maintains traffic flow that underpins the regional economy.

The presentation will discuss past successes, recommended future actions such as deck resurfacing with an impervious overlay, strategic steel grid deck panel replacement, repair of deck joints and concrete headers, other deck and floor framing repairs, and current implementation, highlighting how planned preservation and staged replacement support both asset performance and financial sustainability.

The RFK East River Suspension bridge turns 90 years old in 2026. Two decades of past investments, along with ongoing projects will ensure the longevity of critical suspension bridge components well into the future. In addition to reducing the loads on the main cables, work on the RFK is improving the aerodynamic performance of the bridge, ensuring its resiliency during seismic events, and improving accessibility for this critical crossing that spans the East River and connects the borough of Queens to the Manhattan and Bronx boroughs. This paper presents the history of the bridge, previous improvements made to the suspended spans as well as ongoing investments, along with some of the more interesting planning and technical challenges encountered during the implementation of the various improvements.

Halifax Harbour Bridges (HHB, a commission of the Province of Nova Scotia) owns, operates, and maintains two transportation corridors, spanning Halifax Harbour with the AngusL. Macdonald Bridge (1955) and the A.Murray MacKay Bridge (1970 the Narrows Corridor). Over the past 25 years, the Macdonald Bridge (and associated corridor) has seen significant reinvestment; in contrast, the MacKay Bridge is beginning to show signs of its age and lightweight construction.

Recognizing the Narrows Corridors regional importance, a timely decision is required on how best to maintain the corridor for future generations. This presentation outlines HHBs approach to managing the existing structures and planning underway for the future.

1) Identify, Investigate and Act
As age‑related issues accumulate, HHB is focusing the inspection program on known risks and uncovering unknowns. Findings are driving actions: ongoing monitoring, modelling, nondestructive testing, and targeted repairs to corrosion‑susceptible and fatigue‑prone details. A risk‑based framework informs scope, sequencing, and funding for maintenance and capital projects.

2) Maintain the Existing Structure
HHB is pivoting its capital program to the MacKay Bridge with a planning horizon of at least 2040. Design criteria are being rightsized to the remaining service life while tightening requirements for construction‑related traffic interruptions. Emphasis is on lifecycle interventions, traffic safety, and roadway maintenance operations. The priority is public safety and reliable traffic movement but bearing in mind financial constraints.

3) Plan for Future
HHB is advancing a business case that will examine needs, constraints, and options for the Narrows Corridor, including consideration for major rehabilitation and replacement alternatives. In collaboration with various levels of government, HHB will assess constructability constraints, staging, conceptual design, potential realignment, multimodal access and resilience. Current work is preparatory; subsequent phases will require significant stakeholder engagement, timely property acquisition, regulatory approvals, and securing funding and political support.

NYCDOT recently completed a $300+ million rehabilitation on the Brooklyn Bridge to extend its service life, improve safety, and preserve its historic character. Parsons, as consultant to NYCDOT, was lead designer for the project.

The Brooklyn Bridge, opened in 1883, was designated as a National Historic Landmark in 1964 and vital link between the boroughs of Manhattan and Brooklyn. The project focused on the bridges approach arches and iconic granite masonry Gothic towers including: replacement of deteriorated brick infill walls, rehabilitation of brick arch block interiors, soil and foundation strengthening, arch block floor repairs, and extensive exterior masonry restoration. The towers were also fully cleaned, repointed, repaired, and equipped with new aesthetic lighting.

Innovative engineering addressed aging foundations. Jet grouting stabilized the Manhattan approach foundations without interruption to active and high traffic volumes on the bridge. Original brick infill walls were replaced with reinforced concrete shear walls on new footings, clad with brick to match the original walls to enhance load capacity and seismic performance while preserving historic appearance.

Modern systems were discreetly integrated into the historic fabric. New electrical, lighting, ventilation, and HVAC systems within the arch blocks improved functionality, climate control, and energy efficiency. For decades the famous bridge towers stood unlit. The project also included energy‑efficient LED aesthetic lighting of the tower, enhancing the bridges aesthetic appeal and demonstrating a commitment to sustainability.

The project required stringent preservation and multi‑agency coordination. Careful material matching, including compatible mortars, masonry and all visible details, ensured the bridge remained structurally sound, operationally modern, and historically authentic for future generations.

Norconsult/Aas‑Jakobsen has been involved in the assessment and strengthening of Norwegian suspension bridges for several decades. As these structures age and traffic loads increase, the need for targeted retrofitting has grown significantly. Furthermore, some of the original technical solutions such as bearings do not function as intended and therefore require significant interventions.

This paper presents experience from a small handful of projects over the past decade, covering evaluation of global structural behaviour, strengthening of stiffening girders, and retrofitting of bearing systems. The bridges are from the 1960s and have main spans ranging from approximately 150250 m. The stiffening girders consist of both I‑beams and truss structures.

Particular attention is given to chosen retrofitting and strengthening solutions and lessons learned including cases where design approaches proved insufficient with the aim of providing practical guidance for bridge operators facing similar challenges.

The Danish Road Directorate will in 2027 and 2028 replace the existing modular expansion joints on New Little Belt Bridge, all‑in‑all 6 expansion joints, with new ones supplied with noise damping measures. To improve the service life and reduce the future maintenance works on the new expansion joints, 2 x 2 new hydraulic buffers will be installed in 2026, to reduce the accumulated movements of the bridge girder coming from mainly traffic on the bridge. The 2 x 2 hydraulic buffers are placed and fixed towards the main span girder and anchored to the four tower legs. The hydraulic buffers will allow for slow movements as temperature impact, like what you find on many new designs of major suspension bridges.

The experience with 23 years of maintenance on especially the expansion joints towards the 600‑meter‑long main span, has shown that constant movements from the traffic loads, especially heavy trucks, have a major impact on the service life of the wear parts of the expansion joints. The expectations to the effect of the hydraulic buffers are that the accumulated movements will be reduced to around 10% of the current accumulated movements. The reduced movements will also have a positive secondary effect on the wear on wind bearings, and the pendulum supports at the pylons. Considering 100 years remaining service life of New Little Belt Bridge, there will in daily maintenance costs be an expected saving of approximately 15%. The cost savings are mainly related to the reduced traffic interruption costs, as there will be costs related to installation of the hydraulic buffers and future maintenance of them.

This project examines the assessment of lateral forces acting on pot bearings on the Øresund Bridge in preparation for future bearing replacement works. As a critical transport connection between Denmark and Sweden, the bridge carries both highway and rail traffic and is supported by more than 200 pot bearings of varying sizes and configurations.

These bearings play a key role in maintaining the structural performance of the bridge while accommodating movements caused by temperature variations, traffic loading, and structural interaction effects. Understanding the magnitude and distribution of horizontal forces in the bearings is therefore essential for planning safe and effective replacement operations.

The study focuses on the evaluation of lateral movements and horizontal forces within the bearing system, with particular attention to the interaction between adjacent supports and the influence of temperature‑induced movements along the steel superstructure. Thermal expansion and contraction can generate significant horizontal forces between supports, particularly under conditions of uneven temperature distribution along the bridge.

Future bearing replacement will require controlled lifting of the bridge using hydraulic jacks. During these operations, temporary works must be implemented to manage lateral movements and maintain structural stability while vertical loads are transferred through the jacking system. The design of temporary lateral restraints must therefore account for the interaction between existing horizontal forces, imposed vertical loads, and the behaviour of the bridge structure during lifting.

The project investigates deformation patterns and structural responses under different temperature conditions, including the effects of asymmetric solar heating that can produce differential expansion within the bridge. By analyzing these behaviours, the study aims to inform the design of temporary works that enable safe bearing replacement while improving understanding of bearing performance under complex loading conditions. The findings contribute to the development of more robust maintenance strategies for long‑span steel bridges.

The Øresund Bridge (Øresund) is the world’s longest cable‑stayed bridge for combined road and rail traffic. Since 2000, it has connected Copenhagen (Denmark) with Malmö (Sweden). The main bridge is 7.8 km long, with a four‑lane motorway on the upper deck and two railway tracks integrated into the truss girder. A 25‑meter‑long expansion joint was replaced on the Øresund Bridge between Denmark and Sweden. This project was notable for its unique integration of innovative technology and sustainability. MAURER acted not only as the designer and supplier of the expansion joint but also managed the replacement process without a full road closure. A distinctive feature of this replacement was that no concrete was removed. The transverse boxes anchored in the bridge superstructure remained intact. This sustainable concept offers both rapid execution and a low carbon footprint. The newly installed joint is a 25‑meter‑long, 22‑ton DS15 Hybrid. Its 15 profiles allow a movement range of 1,500 mm. The traditional swivel joist expansion joint was further developed by incorporating MSM(r) as a sliding material in the innovative bearing springs. MSM(r) is PFAS‑free, highly slidable, and exceptionally durable. This prevents constraint forces and significantly extends the lifespan of the joint. All components of the expansion joint, including those remaining embedded in the structure, were hot‑spray galvanized. Additionally, the expansion joint was equipped with hybrid claws featuring stainless steel on the top side. The corrosion protection system was specially designed for the exposed location above the Øresund, where winds and storms deposit salt on the joint from both above and below.

The George Washington Bridge (GWB), a nearly century‑old suspension bridge spanning the Hudson River between New York and New Jersey, is undergoing a comprehensive rehabilitation to renew its primary load‑carrying systems and improve long‑term durability and functionality. A central component of the Port Authority of New York & New Jersey’s Restoring the George program is the Main Cable Rehabilitation and Suspender Replacement project, which addresses critical elements of the bridges suspension system through improved design and detailing while preserving its historic character and operational permanence.

The project included the in‑service replacement of all 592 original suspender ropes supporting both the upper and lower roadway decks. Each suspender was replaced using a carefully sequenced methodology that redistributed loads through temporary suspenders and localized load transfers to maintain the global behavior of the suspension system. The work incorporated a redesign of the suspender connection details to improve long‑term durability and provide enhanced access for future inspection and maintenance. Existing cable bands were temporarily removed to allow full blasting and recoating, followed by reinstallation. Additional improvements included an enhanced suspender rope coating system and suspender protection.

In parallel with suspender replacement, the project implemented comprehensive main cable rehabilitation, including wire repairs, inspection, strength evaluation, and installation of a permanent main cable dehumidification system to control the internal cable environment and arrest future corrosion. The dehumidification system was supplemented by acoustic monitoring instrumentation for continuous detection and localization of wire‑break events.

The project also enabled significant improvements to pedestrian and bicycle access, including full reconstruction of both sidewalks with new decks, barriers, and railings, and reconstruction of sidewalk approaches to provide ADA‑compliant access.

This paper documents the design decisions and lessons learned from suspender replacement, main cable rehabilitation, and shared‑use path reconstruction on the worlds most heavily traveled bridge.

The Menai Suspension Bridge in North Wales, a historic structure designed by Thomas Telford and opened in 1826, underwent a major program of intervention following the discovery of defects in the bridges vertical hangers. This presentation describes the engineering assessment, design development and construction methodology adopted to stabilize the structure and subsequently replace the hanger system while maintaining the integrity of the suspension chains and preserving the bridges heritage value.

The project was delivered in two key stages. The first stage involved the rapid development and installation of a Secondary Fail‑Safe (SFS) support system following the closure of the bridge when significant defects were identified in the original hangers. This SFS was designed to provide an alternative load path in the event of hanger failure, ensuring that the suspended deck loads could be safely supported by the suspension chains.

A key design constraint during phase one was that the fail‑safes must permit the replacement of the existing hangers during the second phase of works later in the year without needing to be removed. The design was developed at pace following the unexpected closure and involved very close collaboration between all parties (Client, Designer Contractor) to understand the constraints and interface between the temporary works and the bridge.

The SFS design comprised over 600 bespoke fixed length wire rope slings, each made specially for a given hanger, basketed over the chains and terminated to steelwork grillages saddling the bridge lower hanger anchorages. Turnbuckles were utilized to set tension and ensure adequate load distribution without affecting the structural behaviour of the bridge.

The emergency works enabled the bridge to be safely reopened to traffic while a longer‑term repair strategy was developed.

The second stage comprised the design and implementation of a permanent repair involving the replacement of the existing hanger system. Detailed structural analysis and investigations informed the design of new hanger assemblies and a staged replacement methodology that allowed individual hangers to be removed and replaced without compromising structural stability. Bespoke temporary works, including load‑transfer and jacking systems, were used to manage force redistribution within the suspension chains during installation. Structural monitoring and careful sequencing of the works ensured that the bridge remained within safe operational limits throughout the intervention.

The project demonstrates how a combination of rapid emergency response, rigorous engineering analysis and carefully planned construction methodologies can enable complex repairs to be carried out on historic suspension bridges.

The Simon Kenton Memorial Bridge, constructed in 1931 is a suspension bridge with a main span of 1,060 ft. that spans the Ohio River and a historic landmark to both adjoining towns of Maysville, Kentucky and Aberdeen, Ohio. The bridge is owned and operated by the Kentucky Transportation Cabinet (KYTC). In 2003, a major rehabilitation involving steel repairs, and a deck replacement was carried out, followed by wind lock and tower pin and link replacements in 2005. After critical suspender cable deterioration was noted in 2019, the bridge was temporarily closed and retrofitted, reopening in 2020. The Simon Kenton Bridge, now at the age of 95 years old, will require further rehabilitation and preservation strategies including full suspender rope replacement, cable band bolt replacement, hand‑rope and stanchion post replacement, anchorage dehumidification, and miscellaneous steel and deck joint repairs. As part of this project an internal main cable inspection was carried out along with a strength evaluation of the main cable. This inspection will serve as an initial benchmark of the cables condition. The project, which started in the Spring of 2023, is anticipated to complete construction in 2027. The paper will present the project work including best practices to guide bridge owners who are considering the suspender rope replacement and connection detail modifications, as well as rehabilitation and improvements to suspension bridge elements.

The owners of the two Danish suspension bridges, Great Belt Bridge East Bridge and New Little Belt Bridge, have for their ongoing inspections and maintenance of the main cables, in year 2025 and 2026, equipped the bridges with two moving cable platforms/cable gantries. Great Belt Bridge had their first cable gantry designed and installed in 1999–2000 but decided in 2025 to replace the cable gantry with a new and improved version. New Little Belt Bridge is 28 years older than Great Belt Bridge but has never had a cable gantry for the inspections and maintenance works. Any inspections and maintenance work on the main cables of the now 56‑year‑old New Little Belt Bridge, were done from walking on the cables, from a lift system or from temporary platforms.

New and upgraded requirements to the safety for workers on the main cables, the upcoming kind of maintenance work that is supposed to be executed on the main cables and general requirements to documentation of the safety on movable platforms, has resulted in a need for the two new cable gantries. The abstract will elaborate on the basis for the design, the design execution and the decision on how to tender out the inspection gantries, including a retrospective view on the past 25 years of development of cable gantries.

The San Francisco Oakland Bay Bridge West Span is an iconic structure that is contemporary to the Golden Gate. Beyond its function as a vital transportation link, the bridge is a defining element of the Bay Areas skyline as an engineering landmark that embodies both utility and artistry. For almost 90 years, it has served as a lifeline and workhorse for over 250,000 commuters each day, and preserving this historic structure is essential to maintaining the integrity and heritage of one of Californias most significant bridges.

This year, the bridge underwent its first comprehensive suspension system inspection since construction, encompassing a detailed main‑cable assessment, suspender replacement, flow testing, and anchorage evaluation.

Conducted in accordance with the newly issued AASHTO Guide for Risk‑Based Inspection and Strength Evaluation of Suspension Bridge Main Cables (September 2025), this effort represents the first practical application of the guides methodology on an existing suspension bridge, setting a precedent for future risk‑based assessments.

The newly published AASHTO Guide builds upon and advances the earlier NCHRP Report 534by introducing a formal probabilistic framework for assessing cable strength and condition. This new standard to the San Francisco Oakland Bay Bridge enables a more data‑driven and transparent evaluation of remaining cable capacity, supports optimization of inspection intervals, and provides a consistent methodology for prioritizing preservation actions. This approach enhances both technical accuracy and long‑term value by aligning bridge management decisions with quantified risk and performance objectives. The Guide further expands this framework through a formal risk‑based methodology for establishing inspection intervals based on quantified reliability and projected deterioration.

This study assesses the structural health of the Lysefjord Suspension Bridge in Rogaland, Norway, which spans 446 m and features main cables composed of six parallel, fully locked coil cables. After more than 2000 wire fractures were identified within 25 years of service, a comprehensive evaluation of the bridge’s integrity and future performance was initiated by Ramboll in 2023. The project is conducted in two phases. First, a special inspection program combines visual inspection, acoustic monitoring, Magnetic Rope Testing, and Guided Wave Ultrasound Testing to evaluate the external and internal condition of the main cables. Historical inspection data are reviewed to assess the development of wire fractures over time and estimate a likely total number of approximately 2500 breaks. Second, an initial estimate of the residual service life is performed using metallurgical investigations, probabilistic assessments, simulations, and advanced bridge and cable models. The results provide an initial assessment of residual capacity, associated uncertainties, and recommendations for further investigations.

Ensuring the durability of main cables is essential for maintaining the structural safety of suspension bridges. In unprotected suspension and cable‑stayed bridges located in mountainous regions, corrosion of galvanized steel wires has often been reported to occur preferentially on the upper surface of the main cable. Although rainfall, humidity, and temperature are considered to influence corrosion, the environmental conditions responsible for this localized corrosion have not yet been fully clarified.

This study investigates environmental factors affecting corrosion of suspension bridge main cables through field monitoring conducted on four bridges located in two different climatic regions in Japan: a warm and humid region in southwestern Japan and a cooler mountainous region in eastern Japan. Measurements of remaining zinc coating thickness were carried out on the upper, middle, and lower surfaces of the main cables to evaluate corrosion conditions. In addition, environmental monitoring sensors were installed on the cables to continuously record air temperature, humidity, cable surface temperature, and rainfall over approximately one year.

The field measurements showed that significant loss of zinc coating occurred on the upper surface of the main cables on some bridges, while relatively thick coatings remained on the lower surfaces. Notably, bridges located in the warmer region exhibited more severe corrosion on the upper surface than those in the cooler region, despite having similar structural characteristics and service periods.

Environmental monitoring results indicated that these bridges experienced longer wet durations due to rainfall and were frequently exposed to conditions where wet surfaces coincided with high temperatures exceeding 30 C. Furthermore, analysis of atmospheric water vapor content revealed that the warm region maintained larger absolute moisture amounts in the air throughout the year, even when relative humidity was not exceptionally high.

These findings suggest that the combined effects of rainfall‑induced wetting, prolonged wet conditions, and high‑temperature environments with large atmospheric moisture content may contribute to accelerated corrosion on the upper surface of suspension bridge main cables.

With the advent of new methods in main cable preservation systems that postdate previously established guidelines on the frequency of main cable internal inspections, suspension bridge owners are left to implement a cable evaluation program that determines inspection interval and the number of cable segments to be opened for investigation. The intent of the cable evaluation program is to follow a systematic approach, providing clear representative data for comparison during subsequent inspections.

The frequency of inspection may be tailored based on the specific characteristics of a bridge, including cable safety factor, corrosion level, observed wire breaks, inferred wire breaks through acoustic monitoring, performance of dehumidification system, general protection system, the extent of previous internal investigation.

Based on engineering judgement, and as documented in the NCHRP 353 guidelines, it is reasonable to reduce the number of subsequent panels to be opened from the NCHRP 534 guidelines. When output from dehumidification and acoustic monitoring systems indicate a high level of protection with minimal activity, as few as two panels per cable may be selected with the option of two additional panels per cable. Selected panels should include two previously inspected panels, allowing for a direct correlation between the previous wire conditions and mechanical properties. It is, however, prudent to ensure sufficient sampling of wires for laboratory testing demonstrates latent conditions are not present in the wires, affecting the overall performance of the cable system.

To date, several bridges with dehumidified cables have utilized inspection intervals that range from five to ten years; however, no dehumidified cables in North America have undergone subsequent cable inspections following the activation of the cable dehumidification system. WSP has been closely involved with a number of cable dehumidification systems and is scheduled to perform the first post‑dehumidification cable inspections on 4 such bridges in the coming years.

With the rapid expansion of transportation infrastructure in India, the construction of long‑span bridges has increased significantly in recent decades to enhance regional connectivity and accommodate growing traffic demands. Among various structural configurations, cable‑supported bridges such as cable‑stayed and extradosed bridges have gained considerable attention due to their structural efficiency, aesthetic appeal, and ability to span long distances with relatively slender deck sections. Segmental extradosed cable‑stayed bridges combine characteristics of prestressed box‑girder bridges and conventional cable‑stayed systems, where the deck is constructed segmentally and partially supported by external stay cables connected to relatively low‑height pylons. In recent years, several incidents of bridge failures during construction have raised serious concerns regarding construction‑stage safety, structural monitoring, and quality control practices. The collapse of the under‑construction bridge in Bihar, India, represents one such critical incident that underscores the importance of rigorous construction‑stage analysis and monitoring. This study investigates the failure of the under‑construction bridge, focusing on the probable causes that may have contributed to the collapse during the erection stage. Potential factors, such as inadequate construction sequencing, instability of partially completed structural components, improper load‑transfer mechanisms, and deficiencies in supervision, monitoring, and quality assurance practices, are examined. The study highlights the inherent vulnerability of cable‑supported bridge systems during intermediate construction stages when full structural continuity and design strength have not yet been achieved. The findings emphasize the necessity for detailed construction‑stage analysis, strict adherence to erection procedures, and comprehensive structural health monitoring. Lessons learned from this incident are discussed, and recommendations are proposed to enhance construction safety practices, inspection protocols, and risk management strategies for future long‑span cable‑supported bridge projects.

The New Storstrøm Bridge in Denmark exemplifies a modern approach to infrastructure management: creating a comprehensive digital Birth Certificate from the very beginning of a projects life. This 3.8 km concrete girder bridge was constructed using 44 prefabricated girders, pierheads, and piers, all manufactured onshore. Recognizing the opportunity for innovation, the Danish Road Directorate mandated the creation of a Birth Certificate prior to the installation of the first offshore span.

The process involved using drone technology to perform a complete visual registration of all concrete surfaces, both onshore and after placement. These drones captured high‑resolution RGB and thermal images, which were processed into detailed 3D Reality Capture Models (RCM). This model acts as a precise digital twin of the as‑built structure for inspection. Leveraging AI supported by manual verification; the project team identified and catalogued every surface defect within the 3D model. This became a powerful tool for quality control, providing an unambiguous visual reference for communicating with the contractor to agree on acceptable tolerances and necessary repairs.

In summary, this Birth Certificate is not merely an archive; it is a living, intelligent digital baseline. It will serve as the foundation for the bridge’s entire lifecycle management. All future principal inspections will be conducted via drone, with AI comparing new data against this original benchmark to monitor degradation and plan maintenance proactively.

The Danish Road Directorate is committed to follow the approach outlined in the paper for both new and existing bridges, where they have started this approach 5 years ago and have realized the potentials. The development is going fast and the DRD is committed to share their experiences and to implement future advances for optimal OM.

Cable‑stayed bridges are widely adopted in modern transportation infrastructure due to their structural efficiency, aesthetic appeal, and ability to span long distances with relatively slender structural elements. However, their flexible structural systems and large exposed deck surfaces make them particularly susceptible to wind‑induced aerodynamic effects, which may lead to excessive vibrations and potential safety concerns. Therefore, understanding the aerodynamic behaviour of bridge decks under varying wind conditions is essential to ensure the stability and serviceability of cable‑supported bridge structures. This study investigates the aerodynamic performance of cable‑stayed bridge decks equipped with fairings under different wind loading conditions using Computational Fluid Dynamics (CFD). A comprehensive parametric analysis is carried out to evaluate the influence of key geometric and aerodynamic parameters, including the angle of attack of the approaching wind, girder configuration, aspect ratio of the deck cross‑section, and fairing angle on the aerodynamic response of the bridge deck. A series of CFD simulations are performed to determine the key aerodynamic coefficients, including drag, lift, and moment coefficients acting on the bridge deck cross‑sections. To ensure the reliability of the numerical results, mesh refinement studies are conducted to obtain grid‑independent solutions. Furthermore, wind tunnel experiments are carried out on a scaled bridge girder section model with a geometric scale of 1:50 under uniform flow conditions. The experiments consider angles of attack ranging from ‑5 to +5 at 1 intervals, with a wind velocity of 11 m/s. The aerodynamic coefficients obtained from the wind tunnel tests are used to validate the numerical results. The findings provide valuable insights into the influence of deck geometry and wind direction on the aerodynamic behaviour of cable‑stayed bridge decks with fairings. The study highlights the importance of optimizing deck geometry and fairing configuration to minimize adverse aerodynamic effects and enhance the aerodynamic stability of long‑span cable‑supported bridges under wind loading.

Long service lives for major concrete bridges are important and increased focus on sustainability has increased importance of long service lives. Now requirement of 200 years is frequently seen. Design life of modern concrete bridges is mainly governed by chloride ingress, and handling chloride ingress becomes increasingly important for achieving long service lives.

Only within the last 30‑40 years concrete is specifically designed for long service lives (>80‑100 years). This usually requires use of low chloride diffusion concrete, but limited long‑term experience increases the uncertainty of the durability/service life of these concretes. At cracks chloride ingress is increased, but design codes non‑conservatively assumes that this increase is negligible if crack widths are below defined limits. Thereby the uncertainty at cracks is even higher. However, end of service life is usually defined at corrosion initiation, but fully ignoring the propagation phase might be unrealistically conservative for these concretes

To increase understanding of chloride ingress long‑term experiences from The Great Belt Bridge, one of the first bridges constructed with low diffusion concrete, is presented. For 25 years chloride ingress has been monitored by inspections, NDT‑measurement, corrosion sensors and laboratory testing to determine:

• Service life at the governing areas (splash zone) of un‑cracked concrete
• Efficiency of cathodic corrosion prevention in the splash zone by water anodes
• Corrosion development in 0.2‑0.3 mm cracks to test validity of crack limits and evaluate service life at corroding cracks
• Efficiency of surface coating for stopping ongoing corrosion in cracks
• Corrosion development and chloride ingress in 0.05‑0.1 mm cracks to test validity of crack limits and service life

The reliable assessment of cable forces is essential for ensuring the safety, serviceability, and long‑term performance of cable‑stayed bridges. Traditionally, cable force evaluation has relied on short‑term inspection campaigns, during which various measurement techniques such as lift‑off tests and vibration‑based estimations are applied to determine axial forces. While these methods provide valuable insights, they represent only momentary snapshots of the structural state. Given that cable forces may fluctuate significantly over periods of hours or even minutes due to temperature variations, traffic loading, and wind effects, short‑term inspections inherently capture only a limited view of the true force spectrum.

This paper presents a comparative review of short‑term inspection techniques and permanent structural health monitoring (SHM) solutions for cable force assessment. Particular emphasis is placed on vibration‑based monitoring systems, which allow for the continuous estimation of cable forces by tracking natural frequencies and mode shapes. The methodology, underlying assumptions, and accuracy considerations of vibration‑based approaches are discussed in detail.

The advantages of permanent SHM over short‑term inspections are highlighted, especially in the context of risk‑based maintenance strategies for cable‑supported bridges. Continuous monitoring enables the detection of long‑term trends, sudden anomalies, and subtle changes in cable behavior that would remain unnoticed during periodic inspections alone. Early identification of unexpected force shifts improves the ability to detect potential damage mechanisms such as wire breaks, anchorage deterioration, or changes in boundary conditions. By providing a high‑resolution temporal record of cable forces, SHM systems support more reliable decision‑making, optimized maintenance planning, and enhanced structural resilience.

The paper concludes by outlining how the integration of continuous monitoring with short‑term inspection campaigns can form a comprehensive, risk‑informed strategy for maintaining the structural integrity of modern cable‑stayed bridges.

As one of the important and effective means to ensure bridge safety, bridge health monitoring systems are inevitably exposed to harsh natural environments and performance degradation of the equipment itself. This leads to various types of abnormal data such as drift, missing values, and outliers, which can easily trigger false alarms or even render bridge safety assessments unreliable, posing significant operational risks to bridge safety management. To address the above issues, this report proposes an innovative approach that integrates deep learning techniques inspired by computer vision with probabilistic statistical methods for abnormal data diagnosis in bridge health monitoring systems, based on the static‑dynamic, time‑domain, and frequency‑domain characteristics of monitoring data. By analyzing data distribution features, fluctuation ranges, and leveraging the capability of deep learning models to capture nonlinear and high‑frequency characteristics, this approach accurately identifies abnormal patterns such as drift, missing values, square waves, and trends, achieving an accuracy rate of up to 98%. Furthermore, relying on the automated data recognition and engineering deployment of the algorithm, a dual‑mode real‑time + historical architecture is adopted to construct a data quality diagnosis system. This system presents data quality diagnosis results from multiple dimensions, perspectives, and angles, enabling managers to detect and identify anomalies in real time. The solution provides scientific guidance for equipment status inspection and maintenance, offering more user‑friendly and efficient technical support for management decision‑making.

Stay cables are critical load‑carrying components in cable‑stayed bridges, and their structural integrity must be continuously monitored. Key parameters such as tension and damping ratio can be estimated from vibration‑based modal properties. However, long‑term monitoring requires stable and power‑efficient data acquisition systems, along with automated analysis due to the large volume of continuously generated data.

This study presents an autonomous cable monitoring system based on domain knowledge and IoT technology for continuous structural health monitoring. The proposed IoT system enables power‑efficient data acquisition and on‑board processing through edge computing. In addition, a domain knowledge‑based automated peak‑picking algorithm is embedded to ensure reliable and efficient analysis of large‑scale vibration data.

To validate its field applicability, the system was deployed on a cable‑stayed bridge in Korea. Its operational performance was evaluated by comparison with an existing monitoring system in terms of data reception rate, accuracy, and efficiency of tension estimation. The results demonstrate that the proposed system provides reliable and efficient autonomous monitoring for long‑term structural health assessment.

This paper presents the implementation of a health monitoring system for the 15 July Martyrs Bridge and Fatih Sultan Mehmet Bridge, two long‑span suspension bridges crossing the Bosphorus Strait in Istanbul, Türkiye. The monitoring system integrates measurements of environmental actions and loads, structural response, and vibration‑based indicators to support operational evaluation of bridge performance and condition. Environmental parameters monitored include wind, temperature, humidity, and strong ground motion. Structural response measurements at critical bridge locations include displacement, tilt, strain, acceleration, and force. Hanger cable forces for selected long hangers are estimated using vibration‑based techniques, where cable tension is derived from measured hanger frequencies, while for selected short hangers direct force measurements are obtained using force transducers and load‑measuring pins. Modal parameters including natural frequencies, mode shapes, and damping ratios are extracted from ambient vibration data to provide indicators of structural condition and potential damage. Threshold values for monitoring parameters are defined based on design criteria, engineering judgement, and operational experience. The implemented monitoring framework enables bridge owners and engineers to evaluate structural performance, detect abnormal structural behavior, and support data‑driven inspection and maintenance of these critical suspension bridges.

High‑strength steels are known to fail even under static load when three conditions are simultaneously satisfied: materials susceptibility to hydrogen embrittlement, hydrogen concentration above a threshold level, and stress above a threshold level. These conditions are satisfied for the high‑strength steel wire of bridge cables. The drawing process of the bridge wire produces refined microstructures with smaller grain sizes and higher dislocation densities. Because of this refined microstructure, and in contrast to mild low‑carbon steels, high‑strength steel wire becomes brittle due to the absorption and diffusion of hydrogen. At locations of micro deficiencies on wire surface, atomic hydrogen penetrates the interior of the wire, breaks the interatomic bond and causes wire embrittlement. Over time, and with the application of cyclic loads, surface cracks grow, leading to strength reduction and ultimately causing the wire break. Hydrogen ingression into the metal matrix has different sources, including hydrogen absorbed during fabrication and hydrogen diffused from the atmosphere during service. The embrittlement results in reduction in the ductility and fracture toughness. As the wire materials strength increases, its ability to deform plastically (ductility) decreases, which directly influences how cracks initiate and propagate. This paper presents evaluation of the risk of hydrogen embrittlement in bridge wire and its role in degradation of bridge cables. The paper provides assessment of the risk of embrittlement and cracking in cable wire, employing reliability analyses of inspection findings and mechanical properties obtained from tests of wire samples. The evaluation utilizes fracture mechanics principles for the cracked wires and strength degradation modeling over time.

Suspension bridge main cable evaluation and condition preservation is a forethought for suspension bridge owners and operators. Through well documented guidelines for internal main cable investigations and strength evaluations, such as NCHRP 353 and NCHRP 534, owners and engineers may predict with confidence the current safety factors of main cables; however, additional focus into the overall approach of characterizing the near‑term and long‑term affect that hydrogen content has played and continues to play is warranted.

In an effort to provide guidance on a more uniform approach to evaluating this impact, main cable evaluation engineers from WSP, Modjeski Masters and Parsons, and metallurgists from Columbia University, have collaborated to establish recommendations for baseline and subsequent testing during all main cable internal investigations. The intent of this approach is to document the status, along with localized trends, to better understand the potential for hydrogen embrittlement of in‑service wires through examination of data collected during numerous internal inspections. This approach includes two primary testing methods.

First, hydrogen content testing is performed via inert gas fusion‑thermal conductivity method on selected wires that are representative of various wire conditions.

Second, hydrogen embrittlement threshold (ASTM F1624) is used to determine the threshold stress, above which wires are susceptible to embrittlement.

Hydrogen diffuses but is replenished by corrosion. While dehumidification may contribute to purging of diffused hydrogen, the primary focus of dehumidification is to reduce corrosion, and thereby reduce the generation of new hydrogen. Thus, repeating these two tests in subsequent cable inspections will allow for a comparison of the hydrogen development in wires, as well as a demonstrable impact of the dehumidification system on preserving the wires.

This paper will present recommendations for baseline and subsequent testing for hydrogen content and hydrogen embrittlement based on results from previous main cable internal investigations of suspension bridges.

Suspension bridge cable wire undergoes a complex deterioration process. Moist air and water can enter the cable at weak points in the protection system. Once inside it cannot easily escape creating humidity conditions that are different from those outside. The protective zinc galvanizing coating on the wires will break down over time and corrosion products will accumulate which will encourage longer periods of dampness, tending to increase the severity of any corrosion mechanism.

Bridges around the world had wire manufactured with a thin protective layer of zinc galvanizing. However, when water is present this layer will itself corrode, forming soluble salts such as zinc oxide. This action slowly depletes the zinc until gaps appear at which point corrosion of the steel can commence. Once the galvanizing has been locally depleted, the galvanic reaction with steel takes place and hydrogen is then produced.

As wires gradually corrode, at certain sites on the wire surface, cracks will initiate and propagate across the wire leading to ultimate fracture and failure. Cracked and broken wires are generally a serious problem for a bridge. Strength calculation models such as NCHRP 534 will produce lower evaluated strengths than for a cable in the same condition with no cracked wires.

This paper examines the efficacy of main cable dehumidification in preventing further deterioration with examples from bridges where cable dehumidification has been installed for over 15 years.

The benefits of reducing deadload is covered in the paper as is the role of hydrogen in the deterioration process and the effect of the presence of hydrogen within cables that have already been dehumidified.

The collapse of the Francis Scott Key Bridge highlighted the vulnerability of many existing bridges spanning navigation channels. With narrow main spans and structurally vulnerable piers, many of these bridges would require hundreds of millions of dollars in environmentally disruptive in‑water protection works to meet modern design standards. Given limited funding and competing infrastructure priorities, upgrading all such structures is not feasible, yet the risk exposure continues to increase as vessel traffic grows in frequency and size. A new, more adaptive approach to managing vessel collision risk is therefore urgently needed, one that complements traditional design‑based methods with operational insight and real‑time data.

Traditional vessel collision risk assessments rely on decades‑old statistical models, extrapolated from sparse historical data and layered with engineering judgment to estimate the probability of collapse. These methods were developed in an era of lower traffic density and smaller vessels, and they struggle to reflect current operating conditions in many busy navigation channels. Meanwhile, shipping traffic continues to grow in both frequency and vessel size, increasing risk year after year. Despite this, little attention is paid to actively monitoring near‑misses that serve as early warning signs of potential disasters.

SpanSight is a channel monitoring system that introduces a new paradigm in vessel collision risk management by shifting focus from rare catastrophic events to observable precursor behaviors. The system enables real‑time detection of near‑miss vessel‑bridge incidents, transforming close calls into actionable operational insights. By capturing and analyzing these events, SpanSight supports proactive engagement with navigational stakeholders, helps identify systemic risk trends, and provides an evidence‑based foundation for targeted risk reduction measures.

While historic Automatic Identification System (AIS) data is routinely used in risk assessments, it is typically down‑sampled, incomplete, and stale by the time it is analyzed. SpanSight actively fuses high‑resolution real‑time AIS data with complementary sensors, to provide enhanced situational awareness and incident verification. This data‑rich approach allows bridge owners to investigate events while details are still fresh, engage constructively with pilots and authorities, and build collaborative partnerships to manage risk and prioritize interventions.

Extending channel monitoring insights into active collision avoidance and traffic control presents challenges due to the low‑probability, high‑consequence nature of vessel strikes. To address this, a multi‑input, multi‑response decision support system (DSS) is proposed, supported by site‑specific operating procedures that aid human decision‑making. This framework emphasizes cross‑agency communication and shared situational awareness, enabling coordinated responses during critical moments while maintaining appropriate human oversight.

Operational Risk Analysis (ORA) for the Øresund Fixed Link (combined road/railway tunnel and cable‑stayed bridge) encompasses the full range of risks that may affect the structures and its users, including routine operational incidents such as ordinary collisions, fires, dangerous good releases etc. as well as external hazards such as vessel collision, flooding, and seismic events. The ORA documents the overall safety of the fixed link and this abstract focuses on the vessel impact component, which represents one of the most significant external threats to the long‑term safety and availability of the fixed link.

Since the bridge opened in 2000, Ramboll has supported Øresundsbron Konsortiet in developing and continuously updating the ORA including the vessel impact risk analysis. Over more than two decades, the methodology has evolved in response to changes in maritime traffic patterns, road and rail traffic volumes, and updates to the structural design basis. A key advancement has been the integration of high‑resolution AIS data, enabling increasingly sophisticated modelling of vessel behaviour, route choice, and deviations in the Øresund. This data‑driven approach has substantially improved collision frequency estimates and strengthened the ability to detect emerging risk drivers.

For the owners, ORA functions as a strategic decision‑support tool. It provides a transparent and traceable basis for assessing whether the overall risk level remains acceptable, whether Eurocode safety requirements are met, and where targeted interventions may be needed. Each update results in a set of actionable recommendations planning design measures, operational procedures, and maintenance strategies that either reduce the probability of vessel impact or mitigate its consequences.

The paper presents the development of the vessel impact risk analysis from 2000 to today and illustrates how a systematic, continuously updated ORA supports robust, long‑term asset management decisions for bridge owners.

An earthquake with a magnitude of 7.5 occurred off the east coast of Aomori Prefecture on December 8, 2025. During this event, a PGA (Peak Ground Acceleration) of 466 gal was recorded at the K‑NET Hachinohe station (AOM012), located 82 km from the epicenter. In the Muroran area, where the target bridge is situated 186 km from the epicenter, a PGA of 114 gal was recorded at the K‑NET Muroran station (HKD132). Although the bridges response to the main shock was not captured, measurements were obtained during an aftershock on December 12, 2025, which registered a PGA of 35 gal at the same station. This study reports the characteristics of the aftershock waves and the dynamic response of the bridge. The Hakucho Ohashi Bridge is a long‑span suspension bridge with stiffening box girders crossing Muroran Bay in Hokkaido, a cold and snowy region of Japan. The bridge has a total length of 1,380 m with a 720 m central span; its main tower foundations are supported by artificial islands reaching depths of 57 m and 73 m below sea level. The bridge is structurally monitored year‑round using IoT‑ based optical sensors to measure axial strains in the girders and the accelerations of the main tower. During the aftershock of the quake, while the measured maximum acceleration at the tower base was 17 gal in the longitudinal direction of the bridge, the tower top reached 83 gal in the transverse direction. The maximum horizontal bending strain of the girder at the midspan of the center span was approximately 15 micro‑strain, a level comparable to those observed under strong winds.

Aging of main suspension cables remains a critical concern for suspension bridge owners, as corrosion, subsequent wire breaks, and other deterioration increasingly limit structural reliability and operational capacity. Many suspension bridges worldwide are now subject to load restrictions or reduced traffic flow because their original main‑cable systems were not designed to be replaceable. This constraint forces owners to manage significant safety risks and escalate maintenance costs over the bridges service life.

This paper examines the specific degradation mechanisms affecting traditional parallel‑wire main cables, with emphasis on how their tightly packed, non‑replaceable configurations, using friction load transfer mechanisms, all amplify fretting corrosion, hinder internal inspection, and accelerate aging effects. The discussion highlights how current state‑of‑the‑art cable conceptual though efficient in design create long‑term limitations by preventing strand‑level intervention. These conceptual barriers directly impact bridge operation and restrict the owners ability to maintain safe traffic conditions.

In parallel, the stay‑cable sector has achieved substantial advances over the last three decades, producing systems that are fully replaceable under service, highly durable, and supported by mature corrosion‑protection technologies. Yet these innovations have not been transferred to suspension bridge practice, despite their clear relevance. This paper proposes leveraging stay‑cable strand technology to detail main‑cable in which every strand is individually replaceable throughout the service life. Such an approach fundamentally changes life‑cycle management by enabling targeted interventions under live traffic.

Two case studies a medium‑span and a super‑long‑span suspension bridge are presented to demonstrate the feasibility and performance of this new concept. Analytical results show that a replaceable strand‑by‑strand main cable can satisfy strength, stiffness, redundancy, and fatigue requirements from modern test base design codes. Furthermore, allowing full replaceability unlocks possibilities of reducing material factors traditionally applied to suspension cables, offering significant cost savings at construction while dramatically improving long‑term maintainability.

This solution provides bridge owners with a transformative tool for service‑life management, minimizing operational constraints and aligning suspension bridge technology with the proven advancements of the stay‑cable industry.

This paper presents the design, construction, and lifecycle management of twin cable‑stayed pedestrian bridges spanning two canals that separate three man‑made islands in the Persian Gulf. The bridges are conceived as architecturally distinctive structures featuring intertwining deck alignments that cross in plan, evoking interlinked forms while creating elevated public spaces. These crossings generate areas for seating with glass deck panels that provide direct views to the water below, enhancing the user experience along a high‑end retail promenade.

The stainless steel pylons serve both structural and functional purposes, incorporating integrated vendor kiosks that activate the bridges as social and commercial destinations. In response to the aggressive marine environment, the stay cable system was designed with a strong emphasis on durability, utilizing corrosion‑resistant materials and detailing strategies to mitigate the effects of salt exposure, humidity, and elevated temperatures.

The presentation will address the complexities of the multidisciplinary design process, including the geometric challenges associated with the non‑linear, intertwining deck configuration, load path resolution, constructability considerations, and tight fabrication and erection tolerances. Construction sequencing, temporary works, and cable stressing operations are discussed, highlighting key challenges encountered during erection.

Prior to opening, a comprehensive vibration monitoring program was implemented to evaluate structural performance under ambient and controlled loading conditions. This program included measurement of vertical and lateral deck accelerations, as well as detailed monitoring of stay cable vibrations. The results identified a susceptibility of select stays to vortex‑induced oscillations under certain wind conditions. To address this, the engineering team developed and implemented a custom system of friction and mass impact dampers, tuned to reduce cable response to acceptable thresholds established in coordination with the owner.

Finally, the paper outlines post‑construction inspection protocols for the stay cables and presents a long‑term monitoring and replacement strategy to ensure continued structural integrity, serviceability, and user comfort throughout the bridges design life.

Structural protection components taken here to include bearings, expansion joints, dampers, shock transmission units, seismic isolators and structural health monitoring (SHM) systems, in particular play a key role in addressing one of society’s greatest needs: facilitating transportation where obstacles exist, by enabling bridges to function safely and efficiently.

Cable supported bridges and in particular suspension bridges cause particular challenges in terms of technical requirements that often are not properly covered by common standards. Specifically accumulated total movements often in combination with harsh environments (wind, chlorides, seismicity) may lead to premature failure of bearings and expansion joints if not designed properly.

Beyond these technical requirements, society has further needs that must not be neglected in the selection and use of such components most significantly in relation to their maintenance throughout their service lives and their replacement when this becomes necessary. Special attention shall be given to possible traffic disruption and environmental perspectives, but also to issues such as noise emissions and user comfort.

This paper aims to outline the key aspects to be considered to address the multitude of requirements technical and societal—with a specific focus on cable supported bridges. Furthermore, the paper shall outline technical solutions that address these specific needs demonstrated by case studies.

Effective inspection and maintenance of cable‑supported bridges relies on structured, risk‑based strategies that integrate condition assessment, prioritized intervention, and continuous lifecycle monitoring. Halifax Harbour Bridges (HHB) applies an element‑level, risk‑based inspection framework that quantifies deterioration and documents defects with standardized terminology, condition ratings, and templates. Inspections capture material and performance issues for steel: cracks, deformation, corrosion, and connection deficiencies using a consistent rating scale to support data‑driven decisions.

Risk‑based prioritization anchors HHBs Asset Management Plan. Bridge elementstowers, stiffening trusses, orthotropic deck panels, and more are preselected for detailed or visual inspections using a framework that considers condition, structural utilization, structural importance, and deterioration models to derive occurrence and consequence, which then set inspection frequencies. Resources are focused on high‑risk locations, especially connections, lower chords, and splash‑zone areas where corrosion and environmental exposure are greatest. Standardized documentation and photo‑referenced defects improve traceability and reduce uncertainty across cycles.

Maintenance strategies are evaluated with life‑cycle cost analysis, aligned to the risk‑based inspection framework and informed by condition, deterioration rate, structural utilization, and importance. For steel, strategy selection considers coating and substrate condition and expected service life. Independent evaluations of the Angus L. Macdonald and A. Murray MacKay bridges identified feasible approaches: localized spot repair, spot repair with overcoating, or full removal and replacement. Recommended systems typically use a three‑coat zinc‑rich primer, epoxy intermediate, and urethane or waterborne topcoat from NEPCOAT‑qualified products. Surface preparation ranges from SSPC‑SP2/SP3 for localized work to SSPC‑SP10 for full refurbishment, with robust containment and hazardous‑waste controls for legacy lead or chromium.

HHBs asset and construction‑risk management frameworks integrate inspections, investigations, benchmarking, stakeholder coordination, and safety reviews from initiation through close‑out, aligning maintenance with constructability, access, traffic, and operational continuity. Together, these practices extend bridge life, enhance safety, and optimize long‑term performance under daily real‑world operating and environmental conditions.

The Helgeland Bridge, located in Nordland, Norway, is a 425 m main span cable‑stayed bridge exposed to a turbulent wind climate. Since its opening in 1991, the bridge has been systematically monitored through inspections, condition assessments and maintenance activities.

This paper presents a structured review of 35 years of inspections, documented damages and implemented mitigation measures. Particular focus is given to wind‑induced excitation of stay cables: The bridge was originally constructed without secondary cable restraints, but significant cable vibrations were observed already during the construction phase. Over time, mitigation measures have been implemented and adjusted based on performance observations and accumulated operational experience.

In addition, the southern side span has experienced continuous settlements of approximately 10 mm per year since its opening. This has required long‑term monitoring and three major re‑leveling interventions to maintain structural geometry and serviceability.

The paper discusses how inspection regimes, maintenance priorities and mitigation strategies have evolved over time. Emphasis is placed on practical lessons learned and the value of systematic documentation for informed decision‑making. The experience from the Helgeland Bridge provides relevant and transferable insights for owners and operators of cable‑supported bridges subjected to demanding environmental conditions.

In the USA and Canada, similar to most countries, suspension bridges are almost always vital links in the nations infrastructure and any element failure, either at the serviceability or ultimate limit state level is likely to cause significant disruption. Most of the latest suspension bridges are being built in China which now has the largest inventory of long span suspension bridges. The US has the second largest inventory of these bridges, but it is also the oldest, with the average bridge age now over 80 years. In Canada, there are a small number of suspension bridges that are also all over 50 years old. This paper will coverrecent and ongoing inspection, preservation and rehabilitation projects on a number of these bridges in both countries to keep this vital infrastructure safe and serviceable. These include projects on the following suspension bridges: Verrazzano Narrows Bridge, Bronx Whitestone Bridge and Throgs Neck Bridge in NYC; Mount Hope and Newport Pell Bridge in RI; Ben Franklin Bridge between PA and NJ; Hennepin Ave. Bridge in Minnesota; Simon Kenton Bridge between Ohio and Kentucky and the Angus L. Macdonald and A. Murray MacKay bridges in Nova Scotia. The paper will also cover some of the latest preservation strategies for suspension bridges including the dehumidification of bridge anchorages and main cables. This innovative and effective method of preventing further deterioration of bridge wires within the cables and the strands within anchorages, is being applied to a growing number of suspension bridges in North America. This is evidenced by the fact that main cable dehumidification is now being installed on all four long span bridges in NYC, that are owned by the Metropolitan Transportation Authority. It will also cover the latest methods of inspection and strength evaluation of main cables with examples from existing bridges.

Norconsult/Aas‑Jakobsen has been involved in the assessment and strengthening of Norwegian suspension bridges for several decades. As these structures age and traffic loads increase, the need for targeted retrofitting has grown significantly. Furthermore, some of the original technical solutions such as bearings do not function as intended and therefore require significant interventions.

This paper presents experience from a small handful of projects over the past decade, covering evaluation of global structural behaviour, strengthening of stiffening girders, and retrofitting of bearing systems. The bridges are from the 1960s and have main spans ranging from approximately 150250 m. The stiffening girders consist of both I‑beams and truss structures.

Particular attention is given to chosen retrofitting and strengthening solutions and lessons learned including cases where design approaches proved insufficient with the aim of providing practical guidance for bridge operators facing similar challenges.

This paper addresses a decision‑support framework for service life management and extension. This framework links

1. service‑life limiting scenario identification,
2. structural reliability‑based service life quantification,
3. decision analysis, and
4. key performance indicators (KPIs) for owners and operators.

Service‑life limiting scenarios are screened based on technical and economic limiting factors as well as compliance with functionality, economic, life safety and sustainability boundaries. Service life limiting scenarios are identified to direct further analysis efforts towards critical structural components and high‑impact deterioration mechanisms. Various integrity management strategies are assessed on the basis of their impact on the service life, structural reliability and potential contribution to functionality, economic, life safety and sustainability boundaries. In a further step, inspections and structural health monitoring schemes are analyzed and ranked by their contribution to an improved structural integrity management. A joint analysis of structural reliability, integrity management, inspection and measurement campaigns is then performed within a risk‑informed decision analysis according to EN 1990:2023 and ISO 2394:2015. Competing strategies are ranked via expected utility including life‑cycle cost, benefit and risks as well as compliance with operational boundaries. A set of KPIs is introduced encompassing the economic, life safety and environmental value of service life management and service life extension. The framework is exemplified by reporting from ongoing service life doubling projects of the Øresund Fixed Link.

The John A. Blatnik Bridge (Blatnik Bridge) carries U.S. Interstate 535 over a major estuary and shipping channel of Lake Superior, connecting the communities of Duluth, Minnesota and Superior, Wisconsin. The bridge sits at the center of the Port of Duluth ‑ Superior; North Americas farthest in‑land freshwater seaport and the Great Lakes top‑tonnage port. As one of two major crossings in the Twin Ports area, the bridge serves as a vital freight and commercial transportation link and serves a daily traffic volume of approximately 33,000 vehicles per day. Deteriorating conditions associated with this 60‑year old span have resulted in high ongoing maintenance costs, load restrictions, and a projected closure by 2030 if the structure is not replaced. In response, the Minnesota Department of Transportation has collaborated with the Wisconsin Department of Transportation (WisDOT) to complete preliminary design for full bridge reconstruction. The project has advanced to contractor procurement with construction of a new tied arch or cable stay structure scheduled to begin in the Fall 2026 under a Design‑Build delivery model.

Historical expansion of the port land mass through uncontrolled filling and long‑term industrial land use before the advent of modern environmental regulations have resulted in known or suspected environmental impairments to soil, groundwater, and sediment in the project area. Construction impacts and costs associated with environmental contamination consistently ranked among the top risks early in the project development process. Since 2022, MnDOT and WisDOT have commissioned various environmental investigations within the proposed Blatnik Bridge reconstruction alignment to better define construction risks and inform engineering design. Thousands of soil, sediment, and/or groundwater samples were collected and analyzed over the course of the investigations. Findings from this work confirmed an expansive contaminant footprint that would be significantly disturbed by future construction under traditional means and methods. MnDOT and WisDOT instead utilized investigative findings to develop structural, drainage, roadway, and utility plans that emphasized avoidance of subgrade disturbance where possible to minimize the generation of contaminated media. The preliminary design also utilizes broad areas of fill to raise the construction grade. This action will create an environmental betterment by capping contaminated media and reducing the potential for future exposures.

This presentation will define risks posed to Blatnik Bridge reconstruction by environmental contamination. The discussion will highlight preliminary design strategies implemented to mitigate these risks which will also benefit public health and the environment.

Corrosion prevention in suspension bridge cables is crucial for extending structural longevity and ensuring safety. A modular dehumidification approach offers a transformative solution by addressing unique design and installation challenges inherent to large‑span bridges. The modular system integrates heaters, blowers, filters, and control units into customized plant rooms, tailored for specific project needs while accommodating varying site conditions. The modular concept simplifies factory acceptance testing (FAT), streamlining the process for efficient and cost‑effective application. Moreover, transportation and on‑site assembly are expedited, minimizing disruption to bridge operations and reducing installation costs. This flexibility empowers engineers to adapt to different environmental and structural demands effortlessly. The paper begins with an introduction to the modular dehumidification system, exploring its design features and core components heaters, blowers, filters, and control units and their integration into adaptable plantrooms. These keycomponents are essential for real‑life use, and insights from major projects show how effective the system is.

The Hgakusten Bridge demonstrated no cable corrosion after two decades, affirming the long‑term effectiveness of this preventive approach. Meanwhile, retrofitted units on the Great Belt Bridge showcased the diagnostic capabilities for optimized airflow and leak detection. In contrast, findings from the Bosphorus Bridge underscored the preventive benefits, revealing extensive wire damage in the absence of early intervention. Together, these examples illustrate the modular systems potential to significantly improve the cost‑efficiency, longevity, and safety of suspension bridge cables, advancing engineering innovation worldwide.

Main cable dehumidification systems utilize large air plenums that house dehumidification equipment, electrical systems, and control systems, serving as reservoirs of dehumidified air. They draw relatively small amounts of air from space and distribute it to cables. This setup causes inefficiencies in air handling, increases contamination risks, and results in higher energy consumption. These systems may also fail to continuously maintain the required moisture content of the air supplied to the injection points. Currently, many North American Dehumidification Plant Rooms are built as insulated containers with exterior doors for maintenance and equipment access, or as custom enclosures with walls partially constructed from large concrete masses.

To overcome these limitations and achieve energy‑efficiency and sustainability goals, WSP has introduced a two‑step improvement to the air dehumidification process used for cable dehumidification.

First, the Process (Dehumidified) Air is configured in a closed loop with an outdoor air intake and connections to the injection blowers. The closed‑loop system offers better control, resulting in consistently lower dew‑point temperatures delivered directly to injection points. This allows an independent, controlled air supply for the bridge cables without relying on oversized open plenums. In the closed‑loop system, Process Air not directed into the cables is mixed with outside make‑up air in a mixing box upstream of the Air Handling Unit. This approach ensures stable drying conditions and continuous protection of the Process Air from equipment, plenum influence, and human contamination.

Second, the air‑conditioning units role, which is currently used to cool the plenum space, has been reconfigured by moving the heat pumps cooling (evaporator) coil into the Air Handling Unit. Placing the cooling coil before the desiccant dehumidifier allows delivery of cold, saturated air to the dehumidifier, enhancing the efficiency of the desiccant wheel and providing better control over the Process Air discharge temperature and absolute humidity.

In many existing suspension bridges, the original cable wrapping coating systems were not designed for the later introduction of air injection systems. After air injection was introduced to the main cables, cracking of the coating in the cable wrapping sections was observed. These cracks allowed moisture ingress during rainfall events, resulting in increased humidity inside the cables and raising concerns regarding a reduction in airtightness.

To address this issue, coating systems capable of accommodating cable expansion and contraction have been investigated. Previous studies evaluated the workability and initial performance of such coatings through applications on actual bridge test sections and elongation tests using laboratory specimens.

This study evaluates the long‑term adaptability of flexible coatings and acrylic rubber‑based coatings approximately five and ten years after application. The evaluation is based on inspection observations from actual bridge test sections and tensile testing of exposed specimens.

The study aims to assess the long‑term performance of these coating systems in maintaining cable integrity and airtightness, and to provide insights into their effectiveness in mitigating humidity‑related risks in suspension bridge main cables.

The surface preparation for repainting hanger ropes of suspension bridges is typically conducted using manual labor, mechanical impact tools, or ultra‑high‑pressure water jets. However, these methods face several challenges, including environmental burdens from fine particles and noise, waste management issues, potential damage to the rope substrate, and the need for shorter construction periods. To address these issues, there is a demand for technological innovation. This paper focuses on a laser ablation technique capable of effectively removing deteriorated paint and rust while significantly reducing environmental impact. The feasibility of applying this method to hanger rope surface preparation for suspension bridges was investigated using actual ropes from the Hakucho Ohashi Bridge in Japan. Based on preliminary experiments, the single‑time laser irradiation range was set at a 60‑degree angle with an ascent/descent speed of 1 m/min for a 44 mm diameter rope. The proposed system consists of a laser ablation unit and two physical cleaning units using wire brushes: a pretreatment unit to remove flaked rust and deteriorated paint, and a post‑treatment unit to clear fine dust following laser ablation. The results demonstrate that two‑pass laser ablation achieves a surface preparation level comparable to manual and power tool cleaning (St 3). Furthermore, the proposed method is highly practical, as it significantly reduces dust and noise while shortening the construction period compared to conventional methods.

Since its opening in 2017, the Queensferry Crossing, a major three span cable stayed bridge over the Forth Estuary, has been closed on four occasions due to snow‑ice accreting to the overhead stay cables and towers and falling onto the carriageway below. Falling snow‑ice fragments have caused damage to vehicles requiring the bridge to be closed to prevent a serious road accident. The implementation of closures has been successful in preventing accidents due to snow‑ice falling. On average, 72,000 vehicles use the Queensferry Crossing every day. Temporary closure of this critical trunk road asset can cause major traffic disruption.

This paper will detail the procedure, pre‑planning, control and implementation of recently installed resilience measures to divert traffic to the Forth Road Bridge under emergency conditions. The resilience measures were successfully implemented on 23 November, 2024 during the most recent snow‑ice accretion event.

To facilitate a safe and efficient diversion of traffic from the M90 Queensferry Crossing to the A9000 Forth Road Bridge, an innovative and bespoke system of automated vehicle restraint barriers have been installed. The new system comprises a series of movable barriers at cross over locations north and south of the bridge, which enable the diversion of two lanes of traffic in each direction. The automated barrier arrangement is complimented by an array of intelligent road studs which light in conjunction with barrier deployment to guide traffic through the diversion. This significantly reduces operative exposure to risk and has significantly reduced the time taken to implement a diversion. The time taken to implement the diversion during the event of 23 November, 2024 was 25 minutes, where previously it would have taken five hours, with a substantial interim temporary diversion to the nearest available crossing some 30km away.

The resilience measures adopted include a bespoke, state of the art weather forecasting tool which utilizes four global weather forecasting models to predict snow‑ice accretion events. The procedure includes the deployment of patrols to inspect for ice accumulation, pre‑mobilization of traffic management teams, barrier deployment teams and spreaders, all coordinated from a 24 hour control room.

This paper will also examine the specific weather conditions that cause snow‑ice accretion on the towers and cables, using test data obtained under laboratory conditions at a facility in CSTB, Nantes, France.

Operational resilience of cable‑supported bridges is increasingly shaped by weather‑driven hazards that sit outside traditional design assumptions. Wet‑snow ice accretion on stay cables can generate falling‑ice risk, force unplanned closures and erode public confidence. This presentation describes how a data‑driven Smart Bridges approach, developed for the 2.7 km Queensferry Crossing, has transformed the way operators anticipate, assess and mitigate this risk. Arup, BEAR Scotland (on behalf of Transport Scotland) and specialist meteorologists Kjeller Vindteknikk (KVT) co‑developed an Ice Accretion Forecasting and Decision Support System that converts complex meteorology and live bridge observations into clear, actionable operational guidance.

At its core is a bespoke meteorological model designed for the highly localized conditions that trigger wet‑snow icing on inclined cables. The system processes multiple forecast datasets to derive refined wet‑snow precipitation indicators, which are then passed through a tailored risk model to generate probabilistic accretion risk levels. These forecasts are fused with live data streams from bridge weather sensors and operational feedback, and presented through an intuitive dashboard that supports duty managers in making timely, evidence‑based decisions. The operational impact is demonstrated through a development history driven by disruptive events between 2019 and 2021, followed by phased validation, requirements workshops and live piloting.

The system has successfully predicted a major icing event during live operation, enabling pre‑emptive traffic management and diversions to protect the travelling public, while materially reducing false positives and unnecessary resource‑intensive patrols. Beyond the technical solution, the presentation highlights lessons learned in cross‑disciplinary collaboration, governance, and integration into safety‑critical operational protocols, and sets out how the same Smart Bridges principles can be applied to other climate‑driven hazards to support resilient, network‑wide bridge management.

This paper presents the development of a probabilistic forecast system that aims to predict the ice risk due to wet snow accumulation on a cable‑stayed bridge (Queensferry Crossing) across the Firth of Forth, Scotland. Since it opened to traffic in 2017, the bridge has been closed on four occasions due to ice falling from different bridge elements above road level and landing on the carriageway. This has forced the road authorities to do frequent patrols and visual inspections of the bridge during periods with winter precipitation to ensure that the towers/cables are ice‑free, even though snowfall relatively rarely leads to ice accumulation. The goal of the development of a revised forecast system is therefore to reduce the number of unwarranted patrols (false alarms) to a minimum, limiting the need for visual inspections to periods with real risk of ice accumulation only. The forecast system has been developed by Norconsult and Arup on behalf of BEAR/Transport Scotland.

The present system is based upon global weather forecast datasets (GFS and GEFS) further refined by a regional weather prediction model (Weather Research and Forecasting model) to yield high‑resolution meteorological data at the relevant site. The meteorological data are subsequently processed by an ice accretion model to yield hourly values of ice build‑up over the next 48 hours.

By utilizing a total of four global forecasts (GFS and three GEFS members) the system accounts for the uncertainties related to the future development of the present weather system. To further reduce the risk of false negative predictions, the system combines data from the nine closest model grid points and nine different vertical levels (spanning the vertical extent of the bridge towers) from each forecast, yielding a total of 324 time series on which to base the risk assessment on.

The probabilistic ice risk forecast is updated every six hours and is visualized via a web‑based platform. The system issues risk levels (low, moderate, high or severe) based on each forecast individually, as well as a total risk level based on all forecasts combined. A pilot version of the system is currently operational, and it has issued significantly less false alarms compared to current practice during its limited pilot period. Furthermore, the system issued a severe ice risk alert on one occasion during the 2024‑25 winter leading to visual inspections and subsequently closure of the bridge due to observations of falling ice.

The New Ölfusá Bridge is a single pylon cable‑stayed bridge, under construction near the city of Selfoss. The bridge will be the first of its kind in Iceland and is part of the project Ring road (1) around Ölfusá, moving the current ring road to outside the Selfoss city area. The bridge will have a total length of 330m, with its single pylon founded on the Efri Laugardlaeyja island, and its two cable stayed spans spanning the Ölfusá River either side. Ramboll has performed the detailed design of the bridge for the contractor TGVerk. The end client and owner of the bridge will be the Icelandic Road Administration, VG.

The bridge is built in an area with substantial environmental actions, such as large earthquakes, significant wind speeds, and freezing temperatures. Additionally, it is crossing an active fault line, and the design therefore had to consider a potential 1m permanent ground rupture displacement. All this led to the development of special details able to accommodate these extreme effects. Under large earthquakes the pylon footing is designed to slide to limit the load effects on the structure. This feature has added robustness to the system, and reduced cost and maintenance hours associated with special devices such as viscous dampers. For the stays, special passive de‑icing HDPE pipes is adopted. This, to reduce the impact from accreted ice on the stays falling onto the road. In this paper, the different mitigative measures provided are described in detail, and the analysis and design methodologies adopted for specifically treating the earthquake and wind loads are explained.

The permanent road and railway connection between Sicily and the Italian mainland is a complex infrastructural system which includes the single‑span suspension bridge crossing the Strait of Messina and the associated road and rail links on land. This huge infrastructure is located in a severe physical environment, plays a central role for national transport connectivity and has a main span of 3300 m. These exceptional features requested the adoption, in the present design phase, of exceptionally stringent performance requirements, to ensure both structural safety and operational continuity. In fact, the design specifically focused on durability, inspection, and monitoring, starting from two fundamental principles: redundancy and technology. Regarding durability, redundancy and technology led to the selection of several protection systems against the ageing of materials, and design solutions to reduce mechanical wear and tear of structural components. Redundancy and technology applied to inspection led to the adoption of inspection systems and access to provide redundant, parallel and, in some cases, also comfortable, approaches to the structural elements. Similarly, redundancy and technology, also led to the adoption of state‑of‑the‑art technologies for remote inspection and control of the structural elements. Redundancy and technology find their most significant expression in monitoring systems. Thanks to the application of BIM, of a comprehensive digital model, and of artificial‑intelligence‑based analytical tools, the monitoring systems will be able to shift from a scheduled maintenance method to a predictive maintenance method, tailored to the specific features of the structure and its environmental context. This life‑cycle‑oriented approach conceives the design as an integrated system encompassing structural, computer, electronic, and mechanical engineering. Finally, an important role is played by the contribution of technology to structural safety: for instance, the use of specific systems ensures an effective fire‑protection of the structural components.

The new 32‑kilometer Bataan Cavite Interlink Bridge (BCIB) Project is conceived not only as a landmark marine crossing over Manila Bay, but as a long‑term national asset requiring a comprehensive and resilient operations and maintenance (OM) framework. Given the bridges complex configuration comprising land approaches, marine viaducts, and cable‑supported channel bridge sits sustained performance over a 100‑year design life depends on structured inspection regimes, advanced access systems, and technology‑enabled maintenance strategies.

The BCIB Operations and Maintenance Manual establishes a lifecycle‑oriented regime covering all major asset groups and associated systems. Central to this framework is a Bridge Management System (BMS), which functions as the primary platform for inspection records, defect classification, maintenance programming, and long‑term cost planning. For the cable‑supported bridges in particular, the Manual defines a combination of General, Principal, and Special inspections, with a maximum six‑year interval for Principal Inspections, ensuring close visual assessment of critical components such as stay anchorages, bearings, and expansion joints.

Complementing physical access strategies, the BCIB incorporates a Structural Health Monitoring System (SHMS) to track structural behavior, vibration, displacement, environmental exposure, and cable performance. Continuous monitoring reduces reliance on intrusive inspections, supports condition‑based maintenance, and allows predictive intervention before deterioration accelerates thereby extending service life and reducing resource‑intensive repairs.

Through the deliberate integration of engineered access provisions, advanced monitoring technologies, and lifecycle‑based preventive maintenance, the BCIB establishes a forward‑looking model for the inspection and sustainable management of cable‑supported bridges. This approach not only safeguards structural integrity and public safety but also aligns long‑span bridge maintenance with evolving carbon reduction and environmental stewardship objectives.

The Massna Bridge is a first‑generation cable‑stayed structure, built between 1966 and 1969 to ensure the continuity of the Paris ring road over the railway lines coming from the Gare d’Austerlitz. With a total length of 492 m, it is the longest bridge in Paris, carrying dense and continuous traffic of 200,000 vehicles per day. The deck width is 36 m and the carriageway includes 4 traffic lanes in each direction. This structure is of very high strategic importance for the continuity of the traffic in Paris.

The Massna Bridge features three cable‑stayed spans of 81 m, 161 m and 81 m, with two pairs of stay cables per pylon. The stays consist of bundles made up of locked‑coil strands.

The stay cables exhibit an overall deteriorated condition, with areas of corrosion and wire breaks, which have been subject to close attention for several years. Following an initial assessment of the structural safety level, enhanced acoustic and visual monitoring measures were implemented. Temporary protective measures and cable monitoring were introduced in order to quantify and reduce the progression of the deterioration, without however providing a permanent solution.

In parallel with these protective measures and the enhanced monitoring, studies were carried out to accurately assess the behaviour, safety level and resilience of the structure, and to propose strengthening and rehabilitation methods on the other. A full finite element model was developed in order to calculate the load‑bearing capacity of the structure, in its undamaged configuration and under various damage assumptions.

Finally, an exploratory study of stay cable replacement was conducted based on 3 distinct scenarios: strengthening from above using a temporary suspension system to unload the existing stays, a scenario within the depth of the deck, and a scenario from below using temporary shoring falsework located within the railway lines.

In the engineering consultant world, we are often awarded inspection projects or show up to a project site where we are presented a challenge that our client is looking to us to solve. Often with larger bridges across the U.S. and globally, these challenges are very complex and ask us, how are we going to get to those locations? It’s a common question we ask before any inspection deployment, but there are those times where it is particularly challenging to get to a location that has not been touched in years, if ever. What if as inspectors, rope access technicians, and engineers we had an opportunity to get ahead of the design or construction phases of a structure, engage in these conversations with our clients and the contractor, and develop Inspectability checks along the way? Yes, this is possible and is beginning to happen even today.

This presentation will explore a few different bridges throughout the United States where inspection access tools, equipment, and/or devices could be installed during the design phase; how these opportunities or questions come up and can be incorporated into rehabilitation projects; and how to approach situations where previous access methods put in place are no longer are usable. In addition, we will discuss how to navigate last minute client requests where they identified their priorities when it came to future inspections, pivoting during the construction phases, and the incorporation of safety standards for inspectors and maintenance crews long term. Some bridges discussed could include the Bayonne Bridge (New York), Golden Gate Bridge (California), and more, with a focus on the I‑395 Signature Bridge (Miami, Florida).

The I‑395 Signature Bridge is a landmark, one‑of‑a‑kind structure under construction in downtown Miami. Spanning over1,000 feet and carrying eight lanes of traffic, the bridge comprises six precast segmental arches, including the tallest in North America at 330 feet. Its highly complex and unconventional geometry introduces substantial challenges for future inspection and maintenance operations.

The presentation will help us answer the bigger question: Where can we find innovation and growth across the engineering industry to have these out‑of‑the‑box conversations with our clients for future maintenance of our infrastructure? It will challenge us to think creatively about integrating inspection and maintenance access and even rescue methods on atypical infrastructure that will provide long term benefits to our clients and the consultants performing the work.

The safety and resilience of transportation networks heavily depend on the structural health of bridges, particularly long‑span cable‑supported bridges that often act as critical bottlenecks. Current structural health monitoring approaches remain limited by the lack of seamless integration between infrastructure sensing, structural modeling, and decision‑making. Stand‑alone data‑driven approaches based on sensor data often fail to capture the underlying physics governing structural behavior, while physics‑based models such as advanced finite element analysis face challenges in scalability, computational cost, and real‑time applicability.

To address these limitations, this paper proposes a paradigm shift through a Satellite‑enhanced Structural Digital Twin (SDT) framework. The proposed approach extends conventional SDTs by integrating spaceborne Earth Observation data, including Interferometric Synthetic Aperture Radar (InSAR), with in‑situ sensing and physics‑based modeling. Leveraging physics‑informed machine learning, the framework fuses multi‑source data with governing structural principles, enabling continuous, computationally efficient updating of a high‑fidelity digital representation of cable‑supported bridges.

The key innovation lies in the synergistic integration of Structural Digital Twins and satellite‑based monitoring. While SDTs provide a dynamic, physics‑consistent representation of structural behavior, satellite data introduces a non‑intrusive, large‑scale observation capability that complements traditional sensor networks. This combination enables the simultaneous capture of global structural response and long‑term deformation trends, enhancing the detection of subtle structural changes and improving the correlation between local damage mechanisms and system‑level performance.

The resulting SDT operates as a closed‑loop cyber‑physical system that evolves continuously with its physical counterpart. By integrating satellite observations, ground‑based sensor data, and advanced structural simulations, the framework enables real‑time assessment of structural performance under operational loads, environmental conditions, and extreme climate events. This provides infrastructure owners with actionable insights for risk‑informed decision‑making, proactive maintenance, and lifecycle management.

The paper presents emerging case studies from ongoing large‑scale implementations, demonstrating the feasibility and scalability of satellite‑enhanced SDTs in real‑world applications. The results highlight the transformative potential of combining Structural Digital Twins with satellite‑based Earth Observation to enable continuous, scalable, and cost‑effective monitoring of critical bridge infrastructure.

In 2025, the main cables of the Forth Road Bridge underwent their fifth internal inspection, following earlier investigations carried out in 2004‑05, 2008, 2012, and 2018.

The primary objectives of the 2025 inspection were to examine cable panels that had not previously been investigated and to revisit panels assessed during earlier inspections.

Repeated inspection of selected panels referred to as benchmarking has been used to identify and predict the progression of deterioration, as well as to validate the effectiveness of acoustic (wire‑break) monitoring and dehumidification systems. In contrast, inspecting previously unexamined panels enhances overall coverage and understanding of cable condition, increasing the likelihood of identifying areas that may be weaker than those already assessed.

For more than three decades, dehumidification systems have been used to suppress corrosion and preserve the structural integrity of the cables and anchorages. However, in recent years, ageing plant and control system components, combined with challenges in sourcing obsolete replacement parts, have led to longer and more frequent periods of unplanned downtime.

To address increasing downtime and maintenance demands, a strategic decision was taken in 2024‑25 to refurbish and upgrade the cable and anchorage dehumidification systems, with the aim of restoring and improving long‑term performance and resilience.

This paper presents the findings of the 2025 cable investigation, including evaluations using both the Brittle Wire Model and Random Field methods, and outlines the extensive improvements implemented as part of the comprehensive refurbishment of the cable and anchorage dehumidification systems.

Mount Hope Bridge is a suspension bridge which opened to traffic in 1929 and carries two lanes of Route 114 over the Mount Hope Bay between Portsmouth and Bristol, Rhode Island in the USA. The bridge is owned and operated by the Rhode Island Turnpike and Bridge Authority (RITBA). RITBA owns and operates three other major bridges including the Claiborne Pell (Newport) suspension bridge.

The bridge has a 1,200 ft. (366 m) main span and two 504 ft. (154 m) long side spans. The main cables are 10.75 in. (273 mm) in diameter and are formed from parallel wires. The concrete deck is supported on a steel stiffening truss, and the anchorages are large concrete gravity structures with the Bristol anchorage located on land while the Portsmouth anchorage is in water.

Oil was introduced into the main cables in the 1960s, 1996 and 2000 after significant deterioration and wire breaks were observed. A 2015 cable inspection discovered further deterioration, subsequently, RITBA decided to install a main cable dehumidification system to protect the main cables and to preserve the current safety factor. A separate dehumidification system will be installed in the anchorage chambers which will be integrated into the main cable dehumidification control and monitoring system.

AECOM is the Owners Engineer for the project which is now under construction and includes an internal inspection and strength evaluation of the main cables, replacement of all the cable band bolts, hand ropes and stanchions, the addition of cable bands on the backstays, and new access stair tower to the Portsmouth Anchorage.

The dehumidification of main cables that have been previously oiled is especially challenging and has only been completed on one bridge to date. This paper describes work conducted to investigate and prepare contract documents and drawings for this project.

The spans of the Delaware Memorial Bridge, operated and maintained by the Delaware River and Bay Authority, include twin suspension bridges, each with a center span of 2150 feet and two equal side spans of 750 feet. These twin bridges, constructed in 1951 and 1968, are supported by aerially spun parallel wire main cables, with a circumferential wrapping wire installed during the original construction. With a goal of achieving 40% Relative Humidity (RH) readings at all exhaust points (5 per cable), in 2018 the cables were sealed, and dehumidification plant equipment was installed in each of the four anchorages to provide dry air to each half of the bridge and a control and monitoring system with remote access for data reporting of the sensor readings was brought online, after which the installing contractor performed system maintenance and monitoring services for four years.

WSP (then, Ammann & Whitney), served as the Contractors Engineer during the installation contract, designing elements of the system within the architecture framework established by the Owners Engineer (AECOM). Following completion of the contractors maintenance and monitoring system, DRBA enlisted WSP to perform oversight of the system quarterly maintenance, monthly performance reporting and recommendations for improvement to achieve the project goal. Based on observations of system performance, including variables such as air flow through the cables, performance of dehumidification equipment and system reliability, systemic improvements and refinements to the system were made to optimize the outcomes, as realized through the exhaust RHs. The advancements WSP has aided DRBA in implementing have directly attributed to the current performance of the system, which presently maintains monthly average exhaust RH levels at or below 40%. This paper will focus on specific information related to air flows through the cable, Plant Room performance, injection and exhaust RH, system enhancements and reliability improvements.

Water presence in lower cable anchorages is a long‑term challenge on many old and even new cable stay bridges resulting in a very serious corrosion risk of the cable stays. Uddevalla Bridge was constructed in 2000 with a main span of 414 meters, and 120 modern parallel strand cable stays have since construction been challenged by such water ingress and several attempts have been made to mitigate the problem. The logical mitigation is to prevent water coming into the lower anchorages and this was the first pursued approach. However, unfortunate experiences show that if an anchorage design is not watertight after having been installed, it is very difficult to make it watertight. To handle this enhanced corrosion risk of cable strands, this paper presents a developed concept for controlling and eliminating the corrosion risk and thus extending the service life of the strands for the Uddevalla in Sweden. An automatic continuous moisture monitoring system together with a dehumidification prototype system have been installed and has operated since 2023 and has delivered very promising results in ensuring low relative humidity. The paper demonstrates that over three years the dehumidification system has undergone optimization and been tailored to deal with the as‑built anchorages. Also, anchorage water pockets due to water ingress have been significantly reduced. As part of this process, monitoring records have been analyzed and show that the formation of condensation has been eliminated and the water pockets due to water ingress has been reduced significantly. The paper demonstrates the development and the process of turning the concept into a potential mitigation measure for the cable stays.

To reduce fast longitudinal movements of the Hgakusten Suspension Bridge, primarily from heavy traffic, the bridge was born with two pairs of hydraulic dampers at both abutments. The reduced movement of the bridge provided by the hydraulic dampers ‑ results in less wear and tear on the bridge’s technical installations, such as bearings and joints. This leads to less maintenance works, and the resulting implications for traffic. When the owner of the Hgakusten Bridge, Trafikverket in Sweden, over a longer period noticed an increased wear and tear of bearings and joints, a project was launched in 2020 to refurbish the existing hydraulic dampers, which have been in operation since the bridges opening in 1997. At the start of the refurbishment project, it became clear that the original bridge design and construction work did not include any prepared project for future replacement of the dampers. In the refurbishment project, 3D point cloud scans were performed of the interior of the abutments and tools and equipment were developed to handle 11‑ton anchor points and 12‑ton dampers in confined spaces. Four‑meter‑long grouted tension rods had to be cut out of the concrete anchor block without damaging existing reinforcement. The hydraulic dampers and the hydraulic station had to be made more robust against the harsh environment and finally a simpler solution had to be prepared for possible future replacement of the dampers. During execution, the dampers were dismantled and transported to a workshop, where the actual refurbishment was carried out including extensive tests, ensuring that all hydraulic systems were functioning as intended before the dampers were transported back for reinstallation. This paper elaborates on the experiences gained during design and execution.

The 2nd Van Brienenoord Bridge (VBB) in Rotterdam is a 300‑metre steel tied‑arch bridge opened in 1990. As part of a vital economic corridor, the bridge has experienced substantial traffic growth since its opening, resulting in fatigue problems in the orthotropic deck. To extend the bridges design life to 100 years, a major renovation is planned, where the works will take place on shore. This renovation forms part of a broader renewal program in which the older arch bridge and part of the moveable bridges will be fully replaced.

Assessment on the 2nd VBB showed that deck and hangers needed to be replaced completely. Conducting the renovation on shore offers greater flexibility for removing component and achieving an optimal design. Nevertheless, the design considerations of these elements impact the complete superstructure.

This paper focusses on the design considerations of these new elements and it’s impact. Criteria such as constructability, safety, structural behaviour, costs, maintenance and tolerances played a big role in derive the best suitable design. Different deck design was considered. A big interface of the deck design is its geometry and interfaces with the existing superstructure, which is re‑used largely. The current hanger anchorages are made inside of the box girders. Because of the higher load demand and a change in hanger system from parallel wires to parallel strands, the existing anchorages cannot be re‑used. Tt was decided to move the anchorages outside to dedicated hanger connections. This proved to be the best solution that meets safety and maintenance requirements, but keeping the structural behaviour as close to the original situation as possible.

The replacement design of these critical elements in combination with re‑using a large part of the structure ensures the bridge can keep the connection open for an additional 100 years.

New Little Belt Suspension Bridge in Denmark, constructed in 1970, has a history of steady increasing traffic. Consequently since 2017, fatigue cracks have been observed at approximately 160 locations in the orthotropic steel deck of the. Cracks initiate typically at welds joining diaphragms and throughs. As consequence the bridge deck has subsequently periodically visually been inspected for cracks at known critical details with required follow up by non‑destructive testing and crack repairs. The program for inspection and repairs has been gradually improved based on the crack observations with the objective of detecting cracks for repair at a cost‑effective point in time and with no risk of jeopardizing traffic safety. In the work, it has also been a priority to understand how cracks are influenced by stress distribution through pavement. The condition as well the temperature of the pavement may have a significant impact on fatigue.

However, alternate methods have been investigated to improve and optimize the crack monitoring program further, also considering the challenges with a black and thick asbestos paint on the bridge girder inside that covers the fatigue cracks. The investigated methods have comprised strain gauge monitoring, acoustic emission, use of infra‑red photogrammetry techniques; and indirect methods by assessing the condition of pavement by high‑resolution photogrammetry. The paper presents the pros and cons of the different method with respect to costs and duration associated with the methods as well as how the methods may support a better understanding of the overall reliability in detecting cracks, global crack positions, crack growth rates and interaction with traffic. Finally, the paper also presents a vision for automated detecting cracks by use of autonomous UAV equipped with high resolution photogrammetry cameras.

The orthotropic upper‑level deck of George Washington Bridge, built in 1978, is approaching 50 years of service. Fatigue cracks in the welds between strap plates and ribs appeared in the 1980s, just a few years after the deck was commissioned. Since 1988, eight repair contracts have been carried out to address these issues, reflecting the ongoing challenge of maintaining the deck in a state of good repair.

This paper presents the findings of a study that evaluated 30 years of inspection data (1993‑2023) to identify the frequency, progression and trends of fatigue cracks, assess the effectiveness of past repairs, and consider replacement alternatives using Life Cycle Cost Analysis (LCCA). The evaluation also established the timeframe within which continued crack repairs remain cost‑effective, providing a basis for deferring full deck replacement to a future capital plan. Repair techniques assessed included clamp plate repair, bolted flange repair, reinforcement weld repair, ultrasonic impact treatment (peening), and partial deck replacement. Their effectiveness in restoring load capacity and limiting crack propagation is discussed. Replacement alternatives, including partially filled steel grid deck and various orthotropic deck configuration alternatives, were compared based on constructability, durability, maintenance, and replacement cost criteria, as well as the capacity of the structure to support proposed loading. Life Cycle Cost Analysis (LCCA) was used to quantify long term economic implications.

The findings provide a technical basis of fatigue behavior in welded orthotropic decks, the strengths and limitations of existing repair strategies and potential benefits and limitations of different replacement options. This work offers a practical, data‑driven foundation for planning the upper‑level deck replacement, while supporting continued safe and reliable operation of a critical transportation asset.

The Maryland Transportation Authority (MDTA) owns and operates the Chesapeake Bay Bridge, a twin suspension bridge crossing that connects Annapolis to Maryland’s eastern shore. The Eastbound (EB) and Westbound (WB) suspension bridges opened in 1952 and 1973, respectively. The Westbound spans main cables were constructed of Prefabricated Parallel Wire Strands (PPWS) with cable straps and a neoprene wrapping system. In 2009‑2013, in‑depth main cable investigations were performed, and recommendations were made to extend the service‑life of the suspension systems. In 2014‑2015, main cable dehumidification systems were installed on both the Eastbound and Westbound Bridges, as the first preservation measure.

The second major preservation recommendation for the Westbound Bridge was to install a supplemental cable system. The purpose of the project was to maintain serviceability of the main cables by strengthening the overall suspension system, replacement/rehabilitation of key suspension span components to restore functionality and the original bridge profile. The increased capacity extends the service‑life of the existing cables and allows the bridge to meet increased traffic load demands for the foreseeable future.

The project design began in 2012 with the following concept for the supplemental cable system:

• Two new galvanized structural strand cables installed adjacent to each of the two existing main cables, increasing capacity of the cable system by approximately 12%;
• New strands anchored at tower tops and at front face of existing concrete anchorage;
• New suspenders installed at each existing suspender group

This paper will discuss the investigations and engineering evaluations that were the basis of design performed as part of this project, including the load transfer analyses. In addition, the overall main cable and suspension system preservation program that has been implemented to maintain serviceability will be discussed. Design details and construction lessons learned that were unique to this project will also be presented.

Corrosion damage in locked coil cables can pose a significant threat to the structural integrity of bridges worldwide. This paper presents a comprehensive analysis of the management of corrosion related issues in the cables of the Galecopper Bridge, The Netherlands, to ensure the structural safety of the bridge and maximize availability of the structure to the public. The paper discusses the detection, assessment, temporary strengthening and final replacement of damaged strands.

Temporary strengthening measures were designed, constructed, and monitored, focusing on the most severely damaged strands, to allow time for the design and execution of permanent solutions. The permanent solution replaced the cables through the integration of a state‑of‑the‑art fire‑protected parallel strand system together with high friction saddles around the existing cable system. This allowed both cable systems to be active at the same time and facilitated the replacement of the existing cables while keeping the bridge open to traffic.

While the integration of a modern cable system in the existing structure from a design perspective was a challenge, the replacement operation and safety management during the execution were also a significant challenge. They required the design and testing of a robust detensioning system, the implementation of the detensioning system into the existing structure required extensive engineering and collaboration between all parties involved.

The findings and lessons learned from the Galecopper Bridge case can serve as a reference for bridge engineers and managers facing similar challenges, contributing to the long‑term safety and maintenance of critical infrastructure.

The Älvsborg suspension bridge from 1966 in Gothenburg, Sweden, is one of the busiest bridges in the country, carrying approximately 70,000 vehicles per day. During a routine inspection of a splay chamber dehumidification system in Aug. 2016 an unexpected observation was made. One of the 85 main cable strands was found lying at the bottom of the splay chamber the strand anchorage cable was ruptured. When informed, the Swedish Transport Administration was of course concerned about the bridge’s safety and immediately commissioned safety calculations and a number of different inspections and investigations of the anchorages in all four splay chambers. These activities included endoscopy, ultrasonic testing and acoustic monitoring and resulted in quite reassuring results. Parallel with the investigations, methods for repairing or replacing the ruptured anchorage cable were developed. Several different concepts were developed from which two were selected for further development. As access to the ruptured anchorage cable is very limited due to the surrounding strands, this was a major issue for the repair methods. Therefore, it was decided to test the two chosen methods on full scale mockups to verify the feasibility of the methods and utilize this experience in the final design and execution. This paper describes the different stages of solving this serious problem and presents the final approach to repair the anchorage cable and establishing a new strand anchorage with the original capacity.

As traffic carried across large suspension bridges, such as the Great Belt Bridge, intensifies, the risk of a truck fire increases. A fire on the Great Belt Bridge on 20th November 2020 made us consider that a truck fire on a suspension bridge could lead to hanger cable failure or reduced strength of the cable. The reason is that a truck fire may lead to temperatures equivalent to a hydrocarbon fire. This may cause a permanent reduction in the load carrying capacity and the need for replacement of the hanger cable.

In the 2020 incident, we were fortunate the wind direction carried the heat away from the hanger. However, it made us aware that we need plans in place, including special tools and equipment, to enable the rapid replacement of a hanger in the future. A loss of strength in a hanger does not require full closure to standard traffic, but heavy traffic will be restricted depending on the location of the weakened hanger.

Procedures for hanger replacement were drafted in 2021 in collaboration with Ramboll. These plans made it clear that we needed a stock of spare hangers and special tools to minimize the time between detecting a loss of strength in a cable and installing a new one.

Furthermore, we found that our old aluminum cable gantry required renewal due to ageing of the load‑bearing structures. The new cable gantry was developed in collaboration with COWI, and its design was tailored to accommodate the new tools used for hanger replacement. The longest hanger measures 177 meters and weighs 11 tons, making it necessary to use specially designed lifting equipment.

Large wind‑induced vibrations have been observed for the longest hangers of the Great Belt suspension bridge in Denmark. This paper presents the design of new viscous dampers for the hangers, which in comparison with the existing dampers have longer strokes and are calibrated to target active vibration modes identified via a recently installed monitoring system. The new dampers are designed to reduce fatigue effects and thereby significantly extend the service life of the hangers. The original viscous dampers were installed in 2008 and designed according to best practice and available measurement data at the time. Nevertheless, vibrations with magnitudes up to more than 1.8 metres mid‑hanger have been observed. Vibrations of this amplitude, dominated by the fundamental hanger mode, result in exceedance of the original damper working range, and damage to the damper housing has been observed accordingly. To assess the efficiency reduction of the original dampers due to the exhausted stroke, and the benefit of an expanded working range for the new dampers, nonlinear finite element simulations have been performed with a representation of the tensioned hanger, presence of a viscous damper and the strongly nonlinear effect of a range limiter. Due to the nonlinear characteristics of the system, effective damping ratios are dependent on vibration amplitudes. An advanced aeroelastic galloping model has therefore been adopted and calibrated to reproduce the measured vibration amplitudes at realistic wind speeds, considering the original damper performance. The calibrated galloping model was subsequently used to determine the hanger response considering the new damper design, and a significant response reduction has been demonstrated. The new dampers have been manufactured and installed during 2024 and so far, no significant vibrations have been observed.

Since its publication in 2004, NCHRP Report 534 has served as the primary national guidance for inspection and strength evaluation of suspension bridges. However, in past decades, substantial advances in risk‑based inspection, nondestructive bridge evaluation, and probabilistic strength assessment have created a need to update existing practice. In response, NCHRP Project 12‑115 was conducted to develop updated guidance which led to the publication of the AASHTO Guidelines for Risk‑Based Inspection and Strength Evaluation of Suspension Bridge Main Cable Systems (released in September 2025). These guidelines introduce a new analysis method to evaluate cable strength, which accounts for the variation of wire strength along the length of the wire (based on the Random Field method), an important characteristic for a ductile material like steel. The guidelines also outline a risk‑based method for determining inspection intervals for various elements comprising the main cable system based on the specific attributes of individual bridges. The objective of this presentation is to inform bridge owners and cable engineers of the important differences between the NCHRP Report 534 and the newly published AASHTO Guidelines in order to assist in their implementation.

Several cable‑supported bridges have suffered either failure of cables/tendons or were posted for lower live load carrying capacity. These failures or reduction in load carrying capacity are due to severe deterioration of high‑strength steel cables/tendons over time. The industry deploys several techniques for monitoring and preservation, such as magnetic flux and acoustic monitoring for wire breaks and dehumidification intended for preservation of bridge cables. Those technologies are employed with the objective of bridge preservation and extension of service life. Nevertheless, various bridges in different parts of the world demonstrated unexpected deterioration varying from increasing rates of wire cracks, and wire breaks to an extent requiring reducing live load capacity, while other bridge cables/tendons suffered catastrophic brittle failures. On August 6, 2025, a catastrophic failure of a main suspension bridge cable caused the death of five people, in Xinjiang Uyghur Autonomous Region in China. That failure was followed by the collapse of the post‑tensioned Carola Bridge in Germany, on September 11, 2024, due to hydrogen‑induced cracking of prestressing steel tendons, and the catastrophic failure of Juscelino Kubitschek de Oliveira Post‑Tensioned Bridge in Brazil, on December 22, 2024, claiming 17 lives. In 2018, a tendon failure on the Wando River Post‑Tensioned Bridge in South Carolina, showed that several of the failed steel strands exhibited brittle fractures. In all these cases, the bridges were inspected, following visual inspection techniques and typical acoustic monitoring, and were deemed serviceable. It is then evident that the current techniques are insufficient to address the surreptitious risk of cracking and failure of wires made of high‑strength steel. This paper describes strategies for risk‑based inspection, monitoring, preservation and service life extension of bridge cables/tendons.

Effective management of suspension bridge main cable systems requires inspection strategies that account for uncertainty, deterioration variability, and the consequences of component failure. Research conducted under NCHRP Project 12‑115 developed a comprehensive risk‑based inspection (RBI) methodology that shifts from prescriptive, time‑dependent intervals to a performance framework. This research forms the basis for the RBI method outlined in the new AASHTO Guidelines for Risk‑Based Inspection and Strength Evaluation of Suspension Bridge Main Cable Systems (released in September 2025). The procedures contained in the guidelines can assist bridge owners in determining inspection intervals for various elements comprising the main cable system based on the specific attributes of individual bridges. This method allows owners to tailor inspection programs to bridge‑specific conditions, historical performance, and available monitoring data, supporting more efficient allocation of resources while maintaining structural reliability. Practical examples will be presented to demonstrate the application of the risk‑based approach and its use in refining inspection schedules and focusing on critical elements.

Since the publication of NCHRP Report 534 in 2004, the Brittle Wire Method (BWM) has been the primary industry tool for evaluating the remaining strength of suspension bridge main cables. Over the past two decades, our team has applied this method on a dozen cable inspection projects, gaining a deep appreciation for both its strengths and its limitations. During this time, engineers across the industry including our group have repeatedly asked whether modern computational power could be used to improve upon the deterministic framework of NCHRP 534. These efforts ultimately culminated in the development of the Random Field Method (RFM), that WSP formalized and published in NCHRP Web Only Document 353 in 2022 together with Modjeski and Masters and Columbia University.

To evaluate differences in the behavior of the two methods, six previously inspected suspension bridges were selected and analyzed using both the RFM and BWM approaches. The estimated main cable strengths obtained from the two methods were similar; however, no clear systematic trend was observed. For some of the examined bridges, RFM produced higher estimated strengths, while for others BWM produced higher values.

To identify the underlying causes of these differences, four key parameters influencing the strength estimation were examined in detail:

1. how cracked and broken wires are considered,
2. the ratio of weak to strong wires,
3. the variability in wire test strengths, and
4. how each method determines the strength of individual wires based on test data.

By isolating these parameters, this paper clarifies why and when the different calculation methods result in different results. These insights provide clearer guidance on when each method is most appropriate and help bridge owners make more informed decisions when assessing remaining cable capacity and long‑term structural reliability.

Long span and complex bridges are critical transportation links and highly valuable societal assets whose continued performance depends on informed and proactive management. This paper describes the Asset Management Plans (AMPs) and Life Cycle Cost Analyses (LCCAs) that Stantec developed for two major international crossings in Ontario: The Seaway International Bridge in Cornwall and the Thousand Islands Bridge near Lansdowne, both owned by the Canadian Federal Bridge Corporation Ltd (FBCL). These studies support long term planning, risk management, and capital investment decisions for these key international crossings.

Stantec developed comprehensive AMPs based on detailed reviews of structural inventories, historical design information, inspection records, and previous rehabilitation works. The AMPs establish current conditions and performance, and evaluate physical condition, structural capacity, remaining service life, geometric adequacy, and compliance with modern safety standards. Key deterioration mechanisms included corrosion of steel, durability concerns in concrete, and risks associated with fracture‑critical cable elements.

Stantec used these findings to develop targeted inspection, monitoring, maintenance, and rehabilitation strategies across multiple planning horizons. Stantec evaluated major interventions such as steel recoating, deck rehabilitation or replacement, main cable preservation, bearing replacement, and substructure repairs in terms of timing, frequency, cost, and associated risk. This enabled the bridge owner to prioritize investments, manage deterioration proactively, and maintain service continuity.

Stantec performed LCCAs to evaluate alternative management, rehabilitation, and replacement strategies, assessing multiple scenarios using Net Present Value (NPV) methodology, using sensitivity analyses to address uncertainty in economic assumptions. The results highlight the tradeoffs between extending service life through intensive rehabilitation and earlier replacement strategies that reduce long term risk.

Together, these projects demonstrate how bridge owners can use AMPs and LCCAs as tools to keep their structures healthy and functioning well. The methodologies and lessons learned are directly applicable to other long‑span and aging bridges facing similar challenges.

This work presents a lifecycle cost analysis (LCCA) framework designed to optimize long‑term maintenance strategies for the seven long‑span toll bridges in the San Francisco Bay Area. These structures vary in age (13 to 87 years old) and structure type, including suspension, steel truss and concrete segmental bridges. The developed framework addresses the unique challenges of managing long‑span bridges compared to conventional bridge networks and addresses the issue of maintaining and preserving the integrity of these vital transportation links. Building on tools developed previously by the FHWA, the framework integrates both bridge element and component level analysis within an Excel‑based environment for ease of adaptability. It accounts for agency costs, user costs due to work zones and detours, vulnerability costs associated with various risks (including fatigue), and future backlog costs from deferred maintenance. Three investment scenarios were evaluated over a 50‑year planning horizon: Spot Repair (reactive maintenance), Preservation Performance (proactive maintenance to sustain Fair or better condition) and Accelerate Rehab (intensive rehabilitation to maximize time in Good condition). Results demonstrate that the Preservation Performance scenario achieves the most cost‑effective balance of condition and expenditure. The Spot Repair approach leads to prolonged periods in Poor condition and the highest overall costs, while the Accelerate Rehab scenario requires billions in additional investment with only marginal gains in bridge performance. The work concludes that proactive maintenance significantly outperforms reactive strategies both economically and operationally. It is expected that the implementation of the Preservation Performance scenario will increase planned investments beyond the current $2.3 Billion BATA 10‑Year Capital Improvement Plan (FY 2024‑33). This adaptable framework, central to the inaugural 2026Toll Bridge Asset Management Plan, serves as a practical, scalable tool for agencies managing complex, long‑span bridges.

Cable stayed bridges are subject to increasing demands arising from higher traffic loads, extended service life requirements, and evolving environmental conditions, requiring advanced lifecycle management strategies to ensure long‑term performance, safety, and economic efficiency.

Lifespan management encompasses three fundamental pillars of lifecycle management: inspection, monitoring, and maintenance. To meet the increasing performance and durability requirements of modern cable‑stayed bridges, these three components must operate in close coordination.

This paper will structure a guideline on how monitoring‑based maintenance, with its high temporal resolution, needs to be implemented as an advanced enabler for inspection and maintenance activities. Continuous monitoring provides detailed insight into structural behaviour over time and supports the early detection of performance changes, enabling timely inspections and maintenance interventions covering for the low spatial resolution of monitoring.

The monitoring concept must be developed through a comprehensive, multi‑threat hazard analysis that considers structural, environmental, and operational risks for each individual structure. Requirements for durable, serviceable, and adaptable monitoring architectures will be discussed to ensure a long‑term reliable system design. Achieving this requires a system design approach that considers the entire monitoring chain from sensor selection and system architecture to data acquisition and interpretation while continuously comparing measured behaviour with design assumptions to trigger appropriate decision‑making processes for the operation and maintenance of the structure.

Oscillating suspenders is one operational risk of suspension bridges, which bridge owners need to deal with both in the daily operation as well in the long‑term asset management. This is also the case on the Great Belt Bridge where oscillating suspenders may not only cause distraction and concern among drivers, but they may also cause damages to the suspenders as well as increasing the risk of fatigue of the suspender cables over time.

On occasions, large oscillations have been observed over the last 25 years and have resulted in installation of hydraulic dampers for the four longest types of suspenders on the bridge. Oscillations are typically induced by stormy wind situations or more rarely as ice induced vibrations. While road vehicle drivers and maintenance staff occasional visually observe suspender oscillations, a structural health monitoring system continuously measure the suspender response together with wind condition and temperature.

This paper investigates this problem from the perspective of the Great Belt Bridge by use of monitoring data captured from the bridge over more than 25 years by a structural health monitoring data. The monitoring data are acquired in parallel with inspection data, non‑destructive testing and Digital Image Correlation (DIC).

The paper look into the correlation of suspender displacement with wind loading and the two‑dimensional spread of wind direction. Suspender oscillations result in a chaotic two‑dimensional displacement pattern, which means suspender displacements in all directions need to be considered. This also need to be taken into account in the fatigue assessment with use of rain flow counting and SN‑curve. As basis for the fatigue assessment, cable support conditions are investigated by gyroscope instrumentation combined with finite element analysis to evaluate bending stresses at the entrance to the sockets. The fatigue assessment is carried out on an annual basis.

Ensuring adequate safety levels of the primary load‑carrying components of suspension bridges is fundamental for the reliability and long‑term management of these critical structures. Components such as main cables, deck girders and associated primary elements govern the structural behavior of long‑span bridges and are central to design checks related to traffic loading, aerodynamic response, and combined environmental actions. Although deterministic design formats aim to ensure consistent safety, the implied reliability of different primary components may vary due to differences in loading assumptions, modelling approaches and governing limit states. Understanding these variations is important for design calibration and assessment of existing bridges. This contribution presents a reliability‑based approach for evaluating the implied safety levels of primary suspension bridge components, demonstrated through a case study of the Hålogaland Bridge in Northern Norway, a suspension bridge with a main span of 1,145 m. The approach combines probabilistic modelling of load and resistance variables with site‑specific traffic modelling based on weigh‑in‑motion data and stochastic representation of wind‑induced response derived from dynamic analysis. Deterministic utilisation ratios are normalized to allow the underlying reliability indices of key structural components to be evaluated on a comparable basis. The results highlight how assumptions related to traffic loading, aerodynamic response and structural modelling can significantly influence the implied safety levels obtained for primary bridge components. The study quantifies how these modelling choices influence reliability indices and identifies parameters that most strongly govern the implied safety levels. The contribution illustrates that uniform deterministic utilisation does not necessarily correspond to uniform reliability. The presented approach demonstrate show reliability‑based evaluation can provide valuable insight into the safety margins of primary suspension bridge components and support discussions on safety calibration, inspection prioritization and risk‑informed asset management of cable‑supported bridges, including identification of governing parameters and sensitivities influencing the reliability of key structural elements.

The Kessock Bridge is a cable‑stayed bridge located on the A9 Trunk Road to the North of Inverness crossing that opened to traffic in 1982. The superstructure consists of a continuous orthotropic steel deck of 1,052 m in total supported by two plans of 32 stays. Shortly after its opening, the bridge deck experienced wind‑induced vibrations (vortex induced oscillations in the vertical direction) that were well documented. These vibrations observed at modest wind speeds were mitigated by deploying tuned‑mass dampers on the main span to control the vertical motion of the deck.

In 2020, with the bridge approaching the 40‑year mark, Transport Scotland/Bear/Jacobs partnered with RWDI to evaluate various wind engineering aspects including: evaluating the local wind climate and on‑site wind measurements, calibration of the numerical structural model using on‑site structural monitoring, wind tunnel investigation of the deck aerodynamic performance, determination of structural wind loads, cycle counting of wind‑induced cable vibrations and an investigation of the traffic‑induced cable vibrations.

Ultimately, the objective of the design team was to conduct a detailed fatigue assessment to estimate the cycles accumulated on the longest cables on the main span due to wind‑ and traffic‑induced vibrations. The results of this investigation would determine if the bridge required a cable replacement program in the next few years.

Based on the extensive engineering work that was performed for this bridge, three main topics will be covered in this presentation:

1. describing the adopted approach to evaluate the aerodynamic characteristics of the bridge and stays that were used to predict various wind‑induced vibrations of the stays (buffeting, rain‑wind and vortex induced oscillations) as well as traffic‑induced vibrations,
2. the adopted method to predict cable vibration cycle counts and corresponding amplitudes and
3. the structural analysis and determination of the fatigue life of the cables, decision making for the cable replacement program.

This presentation aims to support bridge designers to understand and quantify complex aspects of the wind performance and wind‑induced vibrations. Observations and conclusions included in this presentation are applicable to both new design and retrofit of existing bridges.

Should weather protection to lower stay anchorages lose their effectiveness over time, corrosion degradation can initiate, accelerate and lead to strand failures, ultimately requiring the replacement of the whole stay cable. This makes corrosion a significant challenge for the parallel strand cable‑stayed bridges so affected, especially considering the facts that the vulnerable wire lengths within the anchorage cannot be visually inspected, and that stay replacement activity is considerably constrained on a bridge in service.

Previously, the authors discussed how ultrasonic reflectometry can be used to assess stay condition within the vulnerable lower anchorage. This Non‑Destructive Test (NDT) provides wire by wire information on condition, the reliability of which has been evaluated through visual inspection of replaced stays.

The strength of ultrasonic reflectometry is its provision of a detailed snapshot of tested stay condition, but on its own it is limited by its punctual nature and by the intrinsic reliability of the test. While mitigations for its limited reliability exist, it ultimately only provides information on condition at time of inspection, restricting the asset owner to a reactive management regime.

This paper discusses how Bayesian predictive models have been developed by COWI to estimate future stay conditions using NDT results as well as reliability information available for a major cable‑stayed bridge. It then considers how the output from these models can be used to plan stay cable management and replacement in the short, medium and long term, thus enabling a more proactive and optimal management regime.

The Ishikari‑Kako Bridge in Japan, which spans the mouth of the Ishikari River, has a total length of 1412.7 m and has been in service for 50 years. The structure consists of a three‑span continuous cable‑stayed bridge (288 m long) and five units of continuous steel‑composite plate‑girder bridges (one two‑span and four four‑span units). In the cable‑stayed section, the steel box stiffening girder is supported on both the upstream and downstream sides by 16 cables from two main towers. These cables are encased in polyethylene (PE) pipes for corrosion protection, which limits visual inspection of their internal condition. Due to the corrosion and rupture of the waterproof steel anchor covers, the cables near the anchors were visually inspected by opening the PE pipes. The inspection revealed red and white rust on the cables. During the investigation, structural health monitoring was conducted using optical sensors to measure the axial strains of the stiffening girders against predefined thresholds. Furthermore, the current tension force of each cable was estimated using the vibration‑based method (microtremor observation) and compared with data from 2003. These assessments confirmed that the cables remain structurally sound. In the future, new anchor covers with observation windows will be installed to facilitate visual inspections, while the bridge’s structural health will continue to be managed through axial strains monitoring.