The Impact of crash barriers on driver behavior in curved roads, Sri Lanka

Abstract

Traffic accidents represent a significant public health concern, incurring substantial costs. While crash barriers can mitigate accidents and reduce their severity, research on their impact on driver behaviour, especially on gentle curves of single-carriageway, and two-lane roads, is lacking. This study addresses this gap in road safety knowledge by investigating how crash barriers influence speed and vehicle lateral displacement. A flat Class "AB" road with two consecutive mild curves, one featuring a barrier and the other without, was selected for comparison, ensuring similar visual cues for drivers. Data collection involved drones to measure speed and lateral displacement at the beginning, middle, and end of the curves. Statistical t-tests compared speeds and lateral displacements between curves with and without barriers, revealing significant differences (p < 0.05). Subsequent multivariate linear regression explored crash barrier effects on driver behaviour across various vehicle categories, considering different entering speeds, road conditions (wet and dry), and opposite-lane traffic conditions. The regression model indicated that road and opposite lane conditions did not significantly affect speeds and vehicle lateral positions. Instead, middle and exit speeds depended on entering speed and the presence of crash barriers. Vehicle speed at the middle and entry of curves decreased with crash barriers, suggesting an increased perception of safety. The analysis showed that vehicles tended to approach the centerline more in curves with crash barriers, especially heavier vehicles, increasing the risk of head-to-head accidents. Recommendations include widening lanes near crash barrier areas, with modelling providing insights into the necessary additional width.