Editorial

Bridges have long symbolised engineering excellence and innovation. Iconic bridges have been employed as references to great design, used as landmarks of place and age.Today, that legacy meets new challenges, including extreme environmental forces, evolving traffic demands, and the need for rapid condition assessment.This edition showcases the special appeal of the Proceedings of the Institution of Civil Engineers, in its offer of a combined perspective from both academia and practice. Pioneering research and real-world application from across the field are brought together through contemporary dialogue, offering insights that strengthen resilience and performance.Tan et al. (2026) present an informative study on a relatively recently developed form of bridge. Their article ‘Dynamic characteristics of bridges with short pylons and outwardly inclined cable planes’ (Tan et al., 2026) develops understanding of this variation on extradosed cable-stayed bridges, with an examination of their dynamic characteristics. This form of bridge offers various advantages and can be well suited for main spans of 200–300 m, although there remain a limited number of real-world examples.Using Jiayue Bridge in Chongqing, China as a case study, sensitivity analyses were undertaken using a theoretical finite-element method (FEM) approach to assess the impact of various structural variables on the dynamic performance. The results of this exploration provide valuable learning to understand the key drivers of dynamic behaviour and optimisation for this form of bridge.Turning to marine extremes, the construction of sea-crossing bridges around the world is increasing, for which a body of knowledge has been developing to understand the impact of regular wave forces on bridge substructures. Although some studies have looked at the hydrodynamic response of structures to freak waves, a gap in the literature remains with respect to the impact on piers in a bridge configuration.‘Hydrodynamic analysis of bridge piers subjected to extreme waves’ by Li et al. (2026) addresses this, by way of numerical modelling of freak waves, comparing flow field profiles and horizontal forces on cylindrical obstructions with those of linear waves.It was found that, for a single pier, peak climb height, positive and negative loads were all greater than a linear relationship to wave height would predict. Double-pier configurations were also investigated, showing how the interaction of one pier on the other can affect wave and loading characteristics.Designers should note how pier layout and spacing measurably alter loads, making their arrangement and spacing early-stage design levers.In their paper ‘Development of a prototype bridge scour sensor exploiting vortex-induced vibrations’, Campbell et al. (2026) introduce a prototype means of monitoring for what is the largest cause of bridge collapse worldwide: scour.Referencing the CIRIA guide on scour for bridges for current practices and options for monitoring, this paper proposes a new sensor, a fibre Bragg grating (FBG) vortex flow sensor (VFS) device: buried multi-fin elements that activate on exposure and report depth as fins are exposed.First trialled under laboratory conditions, a VFS was installed to a masonry arch bridge in Northern Ireland as a site trial to demonstrate feasibility for real-world application. Although not yet tested with flood conditions, further work is planned to install the device at other sites, optimise the sensor design and investigate the effects of debris on the fins.Moutsianos et al. (2026) present ‘Back-testing the iconic Polyfytos balanced-cantilever bridge to enhance condition assessment’, with an overview of a methodology to assess critical infrastructure by way of measurement and modelling, when existing drawing information is incomplete or unreliable.The study contributes to the problem faced by asset owners around the world of deteriorating bridges, when faced with the need for timely and cost-effective means to manage them. Rapid condition assessment of an asset after a damage (or potential damage) event is also cited as a key problem that might be addressed using modern tools combined with a standardised methodology.A framework of approaches is applied to a case study bridge, the Polyfytos bridge in Western Macedonia, Greece. The second longest bridge in Greece, this has exhibited high deflections to its cantilevers of over 300 mm. Photogrammetry using an unmanned aerial vehicle (UAV) and FEM analysis, with back-calculation of various prestress loss scenarios, has added to previous work on this issue. Similar approaches are likely to be useful for the aging stock of pre-stressed bridges around the world.Next is a study of deflection measurement of a long span continuous rigid frame bridge. In ‘Mechanical performance analysis of long-span continuous rigid-frame bridge’ (Mei et al., 2026), two methods of monitoring were applied to a bridge to measure deflection under live load: non-contact video imaging and level measurement. These in turn were compared with simulated deflection results by way of a finite-element (FE) model of the bridge, finding the model results to be greater than were observed from static load testing.It was shown that non-contact video imaging can be an accurate and effective means to measure deflection for a long-span continuous rigid-frame bridge and infer global and local stiffness consistency, proving this to be a pragmatic way to validate integrity without sensor-heavy installations.Much has been written in recent times on improving the resilience of bridge stocks to flood events, and the management thereof against accelerating climate change. With good cause: this is a recurring contemporary theme which we can only expect to increase in the foreseeable future, with continued climate change and our exposure to extreme events.One of the more significant flood events in the UK in recent times was the Cumbria floods of 2015. Evidence-based flood resilience models for bridges (Beaver and Mitoulis, 2026) uses this as a case study to model the recovery of a portfolio of damaged bridges, using information gathered from the event and its recovery.A retrospective view is applied to a body of disparate reporting and information sources, compiling an evidence-based restoration model from the findings. This could be applied to optimise recovery efforts to a similar event in the future, based on local and regional priorities and the availability of resources.As an interesting additional observation, the study also demonstrated the trend of design measures taken to increase resilience for flood events. Compared with the pre-existing damaged structures, bridges which were replaced or repaired typically demonstrated features such as removed or reduced piers in rivers, and targeted choices of material selection.‘The development of RL loading for bridges on the London Underground network’ (Lane and Bessant, 2026) examines Railways London (RL) loading and its relevance for engineers working with bridges on the London Underground and other light rail networks, or who have an interest in its history and that of the development of rail load models for design standards.A brief history of rail load models in the UK is presented, leading into a more detailed discussion on the development of RL loading, as incorporated into Eurocodes by way of the National Annex in 2020.This provides an invaluable reference for any further update of the standards in the future, perhaps in response to changing requirements and conditions in rolling stock and track. Benefit will also be provided to those designers who wish to understand the intricacies of the load models, and where they represent a close match to, or divert from, actual loading.Our final paper – ‘Curvature limits for composite steel box girder bridges’ by Khalafalla and Sennah (2026) – delves into some of the detail behind design rules and guidance in Canadian and American bridge design standards, regarding the design of curved composite steel box girder bridges. Namely, for bridges meeting various criteria to define their curvature as slight, that these may then be treated as straight, simplifying the design process.Design standards are formulated based on a balanced consideration of accuracy, appropriate conservatism for safety and simplicity of application to a range of use cases. The perennial trade-off faced by the authors of design codes is achieving a balance between these, while ensuring safety in all cases. This study interrogates this with respect to the rules given for shallow curved box girder bridges.A large parametric study (420 FE models) shows that the given code criteria can underestimate stresses, deflections, reactions and frequency shifts for curved systems treated as straight, especially for multi-box, simply supported cases, and provides empirical limits that depend on span L, width B, and radius R.The work underpins some recent revisions to the Canadian Highway Bridge Design Code (CHBDC) commentary, deleting the ‘R >90 m’ simplification and tying curvature limits to geometry and continuity. Designers of curved boxes gain practical thresholds for when treating the bridge as straight can be safely assumed, and when it should not.Together, these studies highlight three imperatives: tune dynamics by design, model environmental extremes, and ground restoration and loading standards in evidence. As climate risks rise and infrastructure ages, such insights will shape the next generation of resilient bridges.With academia and practitioners remaining closely in step to deliver innovation in bridge engineering, we can continue to look forward to new and improved forms of bridges, with improved efficiency of design for material usage, performance, constructability and safe operation. At the same time, the safe continuation of effective performance of existing bridges is maintained through new and improved means, while lessons from the past are learnt and used to improve our future.