Extreme heat disproportionately increases severe road traffic crashes in high conflict settings and among vulnerable road users in California.
DOI: 10.1007/s44327-026-00248-6
URL: https://link.springer.com/content/pdf/10.1007/s44327-026-00248-6.pdf
archive: archived pipeline: cataloged verified
Summary
Time-stratified case-crossover analysis linking ambient-temperature data to police-reported road-traffic crashes from 177 California cities, 2012–2023, with detailed crash-scene information. Extreme heat was associated with monotonically increasing risks of fatal and severe crashes. Effects were larger in high-conflict settings such as intersections, among vulnerable road users (bicyclists and pedestrians), and in crashes involving driver violations characteristic of those contexts (improper turning, failure to yield to pedestrians) as well as instances where pedestrians or bicyclists themselves were the at-fault party. The pattern is consistent with heat-driven changes in road-user behaviour rather than purely vehicular or roadway-engineering mechanisms, and the authors argue that climate resilience (shaded intersections, cooling, enhanced right-of-way protections, recognition of heat as a situational risk factor) should be integrated into Vision Zero road-safety policy.
Key finding
Extreme heat is associated with monotonic increases in severe California crash risk, with the strongest effects at intersections and for bicyclists/pedestrians, consistent with heat-driven behavioural mechanisms (177 cities, 2012–2023).
Methodology
secondary_analysis
Sample size: Exp 1: N=10; Exp 2: N=20
Quality score: 5 / 5