Pavement Friction and Crash Injury Severity: Evidence from Continuous Friction Measurement Data in Florida

Pavement friction is vital for road safety, supporting effective steering, braking, and acceleration. Adequate friction levels help reduce the risk of skidding, yet few studies have explored their link to crash injury severity. This study utilizes high-resolution continuous pavement friction measurement (CPFM) data to examine how friction and other surface features influence crash injury outcomes. In 2023, CPFM data were collected over 2,000 lane miles in the Tampa Bay, Florida area. Friction (Sideway-force Coefficient Routine Investigation Machine [SCRIM] coefficient), macrotexture (mean profile depth [MPD]), and roughness (International Roughness Index [IRI]) were spatially matched to a 0.2-mi buffer around crash sites. A mixed logit model with heterogeneity in means and variances assessed the effects of pavement, roadway, traffic, and vehicle factors on crash injury severity. Findings reveal that the maximum three-point moving average of friction is the most suitable indicator for modelling injury severity. Higher pavement friction significantly reduces the likelihood of serious or fatal injuries. MPD values of 0.8–1.2 mm on dense-graded surfaces are associated with fewer slight injuries, while MPD values above 2 mm on open-graded surfaces increase the likelihood of severe injuries. Additional contributors include roughness, cracking, rutting, raveling, and pavement condition, though some exhibit non-unidirectional effects depending on context.