Risks of bridge collapses are real and set to rise — here’s why
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Deterioration of materials reduces the strength of structural components and is exacerbated by climate change and heat5–7. Extreme weather events that are more frequent and intense expose bridges to increased scour from water flow and more landslides and subsidence, with overall impacts that are difficult to predict8. Thus, ageing bridges are faced with greater risks and uncertainties that make it harder to evaluate their safety.
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Current safety codes and standards still lack guidance on how to deal with the increasing risks of material deterioration and more frequent extreme events. Most codes focus on the design of new bridges, not on evaluating the safety of old ones. Yet the two scenarios raise different problems.
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A few national and international standards do address assessment and retrofitting of existing bridges — such as through technical specifications intended to be used with the first generation of Eurocodes, which are due to be updated next year (see go.nature.com/3wdrmes). However, these standards cover only general principles to assess current needs for structural interventions, not how to avoid bridge collapses in an uncertain future.
Building resilient bridges
Disasters can damage or entirely destroy bridges and cause widespread destruction and social mayhem. But factoring risk into design and maintenance can help ensure the safety of the millions of people who cross bridges on a daily basis.
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This will require four advances. One, more accurate methods to estimate environmental and operational loads that can cope with evolving predictions. Two, better models of how climate change will influence deterioration. Three, harmonized protocols for processing and interpreting data on the structural response of bridges. And four, dynamic decision-support tools that provide timely and relevant information to bridge managers.
Early efforts in this direction are under way. For example, through the International Association for Bridge and Structural Engineering (IABSE), bridge specialists are collaborating to propose safety assessment procedures that consider new hazards and to revise methods for assessing the reliability of existing structures. However, such developments are still not enough to change common practice.
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