Fig. 5: A framework for heat exposure-informed railway investment prioritization.

The figure consists of two panels. a Illustrates prioritization of rail stations for adaptive planning based on projected heat risk, current temperature exposure, ridership levels, and connectivity. The matrix categorizes stations into different priority levels for adaptation measures, ranging from no priority (gray) to high priority (marron). Stations with high ridership, high connectivity, and high exposure to both current and future extreme heat are assigned the highest priority, as disruptions in these locations could propagate system-wide. Conversely, stations with low ridership, low connectivity, and low exposure to both current and future extreme heat are designated as low-priority areas. b Illustrates classification of Amtrak rail stations based on projected heat risk, current temperature exposure, ridership levels, and connectivity. The scatter plot categorizes stations into four primary quadrants using two key variables: future heat risk (based on FEMA’s mid-century projected heat risk) and current temperature exposure (with 40 °C as the threshold). Stations in the upper quadrants face higher projected future heat risks, while those in the right quadrants experience higher current temperatures. Within each quadrant, stations are further mapped based on ridership and connectivity, using their respective average values across all stations as thresholds (represented by the dashed lines). Average baseline connectivity is 5 connections and average ridership is 89,457. This secondary classification results in four categories within each quadrant: low ridership-low connectivity, high ridership-low connectivity, low ridership-high connectivity, and high ridership-high connectivity. The color gradient corresponds to station priority, with marron indicating high-priority stations that warrant immediate adaptation measures, and gray indicating low-priority stations. Data associated with each station is reported in Supplementary Table 3.