Aquaplaning Mitigation via Longitudinal Crown Lines

As climate change drives more frequent and intense rainfall events worldwide, urban areas are increasingly vulnerable to flooding—an issue further amplified by rapid urbanization and industrialization. In this context, aquaplaning has become a critical consideration in road design, particularly as extreme rainfall intensifies the risk of vehicle instability. Previous research by the authors assessed aquaplaning risk across 225 divided freeway alignments, consisting of 2-lane, 3-lane, and 4-lane sections, with a specific focus on horizontal curves, where drainage path lengths tend to be longest and water accumulation most problematic. Building on these freeway-only analyses, the present study examines cases in which critical aquaplaning thresholds—specifically excessive drainage path lengths and water film thickness—were exceeded. A total of 3,375 scenarios were identified within the previously evaluated freeway alignments. To address these conditions, this paper proposes the use of longitudinal crown lines as a targeted geometric mitigation measure. High-accuracy multiple regression models are employed to quantify the improvement rates, demonstrating the effectiveness of crown-line strategies in reducing aquaplaning susceptibility on curved freeway segments.