Assessing Current and Future Extreme Weather Risks: Example of a Pennsylvania Transit Agency

Transit agencies and transportation practitioners are grappling with how to manage risks from extreme weather events, which are already occurring and may be exacerbated by climate change. Examining vulnerability is an important first step to becoming more resilient to future weather and climate risk, but prospective vulnerability assessments can be time-intensive and uncertain. This study piloted an approach to examine climate change vulnerability through the lens of current weather conditions and weather-related disruptions. This approach identifies thresholds of weather events that cause disruptions, capitalizes on readily available data sources and avoids the need for a time-intensive climate modeling effort, and generates estimates of climate change impacts in terms familiar to system operators. For the Southeastern Pennsylvania Transportation Authority (SEPTA) Manayunk/Norristown rail line, the study estimated present and future risk by estimating the probability of extreme weather events, the probability of disruptions and costs during these events, and the magnitude of disruptions and costs from extreme weather events. Thus, future risk is contextualized in current conditions, which facilitates understanding and decision-making within the organization. This risk assessment sets the stage for decision-making about how to manage the risks posed by extreme weather and climate change.