Aquaplaning Thresholds Based on Key Vehicle and Freeway Geometric Factors

Abstract

Wet pavement conditions, exacerbated by adverse weather, play a crucial role in roadway safety, contributing annually to numerous vehicle crashes. This study examines the dynamic aquaplaning phenomenon along 2-lane, 3-lane, and 4-lane urban motorways, aiming to assess key aquaplaning thresholds of water film thickness (WFT) above the pavement texture and aquaplaning speed (APS). In total, 225 alignments of various combinations of geometric parameters were examined. These were also related with a selected range of additional parameters, involving pavement surface characteristics, vehicle parameters, and rainfall intensity rates, resulting in 18,225 combinations in total. The aquaplaning assessment was performed by utilizing the method developed by Gallaway, where, in addition, the critical drainage paths were determined from the algebraic sum between the longitudinal grade and the superelevation rate in 3D roadway geometry. The applied multiple linear regression analysis revealed a high prediction precision for both WFT and APS models. In addition, the performed elasticity analysis revealed that critical parameters for WFT are rain intensity rates, followed by grade, where critical parameters for APS are tire pressure, followed by pavement texture. The present research aims to quantitatively define potential critical conditions related to key road and vehicle parameters and, ultimately, introduce evidence-based variable speed limits. Further work on the implementation of reliable variable speed limits should adopt a more integrated and holistic approach, taking into account additional conditions that further restrict vehicle speed (e.g., skidding, traffic conditions, visibility, detailed driver behavior assessment).