Resilient Bridges under Climate Change: A Review

1. Introduction

Bridges are indispensable to transportation networks, enabling economic activity and social connectivity. However, climate change introduces unprecedented risks: intensified floods, wildfires, and temperature swings are destabilizing structures designed for historical climate norms. For instance, the 2022 collapse of the Fern Hollow Bridge in Pennsylvania highlighted vulnerabilities to aging infrastructure and extreme weather (NTSB, 2023). This review examines how climate change amplifies risks to bridges, evaluates adaptive solutions, and calls for interdisciplinary collaboration to future-proof infrastructure. The key objectives of this review is to (1) analyze climate impacts on bridge components e.g., foundations, decks; (2) Propose resilience strategies for engineers and policymakers; and (3) highlight gaps in current research and practice.

Figure: Recent Failure of Highway Bridges

2. Climate Change and Modelling

Human-driven greenhouse gas emissions have elevated global temperatures by 1.1°C since pre-industrial times, accelerating ice melt, sea level rise, and extreme weather (IPCC, 2021). For bridges, this means exposure to conditions beyond their original design thresholds. For example, concrete expansion due to heat or scour from flash floods can compromise structural integrity (Melchers & Chaves, 2020). Climate models, such as those developed by the Intergovernmental Panel on Climate Change (IPCC), use Representative Concentration Pathways (RCPs) and Shared Socioeconomic Pathways (SSPs) to project future scenarios. RCP 8.5, a high-emissions trajectory, predicts a 2.4–4.6°C temperature rise by 2100, with cascading impacts on infrastructure (IPCC, 2021). These models inform engineers about long-term risks, such as increased flooding frequency or saltwater intrusion in coastal bridges. Climate projections enable engineers to redesign foundations for higher scour depths; select corrosion-resistant materials for coastal zones; and elevate bridge decks to mitigate flood risks (ASCE, 2021).

3. Climate Change-Related Factors Impacting Bridge Resilience

3.1 Increased Flooding: Intense storms, like Hurricane Harvey (2017), overwhelm drainage systems, increasing hydraulic pressure on bridge piers. The U.S. Federal Highway Administration (FHWA) estimates that flooding damages over 15,000 bridges annually (FHWA, 2023). Scour—the erosion of sediment around foundations—is the leading cause of bridge failures in the U.S. (Wardhana & Hadipriono, 2003). For example, Minnesota’s I-35W bridge collapse (2007) was linked to inadequate scour protection. Floods carry trees, vehicles, and other debris that collide with bridge components. Post-disaster assessments of the 2013 Colorado floods revealed widespread debris-related damage.

3.2 Sea Level Rise: Saltwater intrusion accelerates corrosion of steel reinforcements. A 2022 study found that 15% of U.S. coastal bridges are already structurally deficient (ASCE, 2021). Hurricane Katrina (2005) demonstrated how storm surges can displace entire bridge spans. Elevated water levels also increase buoyancy forces, destabilizing foundations.

3.3 Temperature Extremes: Steel bridges expand by ~1.2 cm per 100 meters for every 10°C temperature rise. Without expansion joints, this can cause buckling or joint failure. Repeated freezing and thawing degrade concrete through internal cracking. The 2021 Texas freeze caused $15 billion in infrastructure damage, including bridges (NOAA, 2021).

3.4 Changes in Wind Patterns: Stronger winds threaten long-span bridges. For example, wind-induced oscillations famously collapsed the Tacoma Narrows Bridge in 1940. Modern designs use aerodynamic decks and dampers to mitigate this (ASCE, 2021).

3.5 Wildfires: Wildfire heat weakens concrete and steel. California’s 2018 Camp Fire damaged 55 bridges, with repair costs exceeding $150 million.

3.6 Increased Corrosion: Corrosion costs the U.S. economy $276 billion annually, with coastal bridges particularly vulnerable. Chlorides from de-icing salts or seawater penetrate concrete, corroding rebar. Epoxy-coated rebar and cathodic protection are common countermeasures.

4. Strategies for Enhancing Bridge Resilience

To safeguard bridges against intensifying climate threats, a multi-faceted approach combining engineering innovation, proactive monitoring, and forward-thinking policy is essential. Design adaptations form the first line of defense. Elevating bridge decks, as recommended by the Federal Highway Administration (FHWA, 2023), reduces flood exposure, while scour countermeasures like riprap (rock armor) and gabions (wire cages filled with stone) stabilize foundations against erosion. Advanced materials, such as fiber-reinforced polymers (FRPs), offer corrosion resistance and durability in extreme temperatures (American Society of Civil Engineers [ASCE], 2021). Beyond these, integrating nature-based solutions—such as vegetated buffers to slow floodwaters or oyster reefs to dissipate wave energy near coastal bridges—can complement traditional engineering. For example, Louisiana’s Coastal Master Plan employs marsh restoration to protect infrastructure from storm surges (Coastal Protection and Restoration Authority, 2023).

Monitoring and maintenance are equally critical. Installing sensors, like strain gauges and accelerometers, enables real-time detection of structural stress or deformation. Retrofitting aging bridges with seismic isolation bearings or shear keys enhances earthquake resilience, as seen in California’s retrofitting programs post-1994 Northridge earthquake. Emerging technologies, such as AI-driven predictive analytics, can forecast maintenance needs by analyzing climate data and sensor inputs. For instance, machine learning models are being tested to predict scour depths during floods, allowing preemptive repairs. Additionally, adaptive management—regularly updating maintenance protocols based on climate projections—ensures bridges remain functional under evolving conditions.

Finally, policy and planning must prioritize climate resilience. Incorporating climate models, such as the IPCC’s RCP scenarios, into design codes ensures bridges are built for future risks (IPCC, 2021). Funding initiatives, like the U.S. Bipartisan Infrastructure Law’s $40 billion allocation for climate-resilient infrastructure, support large-scale upgrades. However, policies should also incentivize community engagement, such as collaborating with Indigenous communities to integrate traditional knowledge on local environmental patterns. For example, Alaska’s transportation department partners with Indigenous groups to design bridges resilient to permafrost thaw. Together, these strategies create a holistic framework to protect bridges—and the communities they serve—from an uncertain climate future.