Rethinking resilient infrastructure for transit in the face of climate change
November 25, 2024
The climate crisis is altering our world in profound ways. More frequent and intense extreme weather events. Rising sea levels threaten coastal communities. These are posing serious challenges for critical infrastructure like public transit systems.
According to the United Nations, more than 3 billion people live in areas vulnerable to climate change. Heat waves, heavy rain, wildfires, and flooding occur more often. And transit agencies need to think about resilient infrastructure.
But how do you measure resilient infrastructure and sustainability? While analyzing these metrics can be challenging, there are tools that can help. One of those tools is the Envision framework from the Institute for Sustainable Infrastructure (ISI). Using Envision to ask key questions early on helps agencies and project teams build a better 360-degree view of how they can combat climate risk as they plan resilient infrastructure.
Envisioning future infrastructure to improve project sustainability
The Envision framework looks at project sustainability across a wide range of metrics. When project teams apply the framework, they can push a project beyond the industry standard. Envision helps make infrastructure more sustainable and equitable. How so? By guiding how to improve the resilience of a project. Here are a few questions from Envision that project teams can ask themselves when starting their project:
- Have you identified short- and long-term hazards?
- How will those hazards change in the future due to climate change?
- Have you developed strategies that are more robust, adaptable, and redundant?
- How are you monitoring the effectiveness of these strategies?
- Are you adapting them to changing conditions?
New York City is looking to reduce flood risk from coastal storms and sea level rise. The Lower Manhattan Coastal Resiliency project at the Battery is addressing the wharf¡¯s declining infrastructure.?
Project teams should seek to answer these questions as early in the planning and design process as possible. The earlier you explore these questions, the more opportunity teams will have to find strategies that increase the potential for infrastructure resilience. For instance, identifying early that sea level rise may impact your project area can allow the design teams to set the elevation of the project higher to adjust for future sea level rise. The earlier these strategies are identified, the easier and more cost-efficient they can be to integrate into the project.
Rising temperatures, rising risks
Transit systems¡ªand their riders¡ªare particularly at risk during extreme heat events. On the transit side, prolonged exposure to extreme heat can damage equipment. It affects rail tracks, overhead wires, and electronic parts. According to the American Public Transportation Association, a third of transit disruptions in the US over the past decade were caused by extreme heat.
Extreme heat is also a danger to people. Users waiting at transit stops face higher exposure. This is especially true at unsheltered stops in urban areas. During an intense heat wave, agencies may need to reduce or suspend transit services to avoid system failures and protect their passengers.?
Climate risk will continue to increase. Working to have proper tools and steps in place to help us improve resilient infrastructure will go a long way.
Flooding threatens transit systems
Heavy rainfall and flooding can disrupt transit systems. Flooded roadways, bridges, subway tunnels, and underground stations cause delays, cancellations, and hazards for users. There¡¯s no way around it, sea level rise is threatening coastal transportation infrastructure.
Even in non-coastal areas, rising water tables can contribute to flooding. This can weaken stable soils. It causes shifts in foundations and utilities, sinkholes, or water infiltration to equipment pits. Major transit hubs in cities like New York, New York, and Shanghai, China, already face increasingly severe flooding during major storm surges today.
Climate risk mitigation for transit
One of the first steps in promoting climate readiness is assessing infrastructure for resilience. As a result, agencies often need to redesign their infrastructure. This can include efforts like elevating train tracks or improving drainage systems. They may also install new equipment that is better suited for harsher temperatures, or they may relocate vulnerable infrastructure away from flood zones.
As an example, let¡¯s look at the Lower Manhattan Coastal Resiliency project at the Battery in New York City. The project is addressing the wharf¡¯s declining infrastructure. Rebuilding the wharf at a higher elevation will help protect the iconic waterfront park at the southern tip of Manhattan from sea level rise through 2100. The project was recently awarded an Envision Platinum Award; it will help safeguard ferry connections to Liberty and Ellis islands.
Risk assessments are important. They allow us to increase our knowledge of both existing and future vulnerabilities. Understanding a weakness allows us to focus on projects that address the greatest risks to the system.
In California, SamTrans is doing a Regional Sea Level Rise Mitigation and Erosion Control Feasibility Analysis.
Balancing mitigation costs based on risks and likelihood
Transit agencies with new capital projects need to consider vulnerability and risk assessments early on. It puts them in the best place to understand the potential trade-offs between more resilient infrastructure and the available budget.
As an example, sites further from floodplains may cost more but may require fewer onsite mitigations. On the other hand, a site that sits on or near an existing floodplain may be less expensive. But it also may require additional elements such as berms or floodwalls or be elevated to reduce the risk of loss in a 100-year event. Planning for the unseen costs of these events allows agencies to manage expectations and better align project budgets with resiliency goals.
Adapting transit to a new climate future
By designing transit systems with future climates in mind and using Envision to quantify project sustainability, we can keep critical infrastructure up and running. This is vital to better serve our communities.
Agencies must take changing climates into account early in a project¡¯s life cycle. That means making sure systems are in place to assess vulnerabilities and prevent future failures. These efforts need to take place prior to setting a scope and budget.
Climate risk will continue to increase. Working to have proper tools and steps in place to help us improve resilient infrastructure will go a long way.?