Evaluating safety margins between skid risks and aquaplaning on curved road sections during vehicle motion

Wet pavement conditions, worsened by adverse weather, are a major cause of vehicle crashes. This study investigates aquaplaning and its relationship with skidding risks on curved urban motorways, aiming to establish safe speed limits and promote variable speed controls. Data was collected from two urban motorways in Athens, Greece, during moderate rain (40mm/h), using the German RAA 2008 guidelines. A 3D vehicle dynamics model assessed skidding, while the Gallaway formula estimated aquaplaning risks by calculating water film thickness (WFT) and aquaplaning speed (APS). The study found that aquaplaning is a more significant risk than skidding, particularly in areas with optimized drainage. Skidding was mainly a concern on tight curves with low friction, while aquaplaning posed a broader risk across various conditions. Moderate rainfall increased aquaplaning risks, emphasizing the need for variable speed limits based on real-time conditions. Elasticity analysis showed that roadway geometry, such as the distance between the carriageway edge and rotation axis, and gradients, influence aquaplaning potential. The research suggests further studies on factors like driver behavior, vehicle characteristics, and environmental conditions to improve speed limit enforcement. Connected and autonomous vehicles (CAVs) could enhance safety by adjusting speeds and navigating curves, implementing evidence-based speed limits under adverse conditions.