THEORETICAL AND EXPERIMENTAL METHODS FOR DETERMINING THE ALLOWABLE SPEED LIMITS ON HIGH-SPEED HIGHWAYS

Abstract

The condition of road pavements significantly affects vehicle speeds, traffic performance, and safety. Surface defects such as cracks, potholes, and irregularities reduce driving comfort, force speed reductions, and increase accident risks. This study aims to justify optimal minimum speed limits for high-speed and main roads by considering improvements in pavement conditions, as well as the growing user expectations for driving comfort and operational efficiency. Field data were collected from four highway sections with different levels of surface degradation. Speed measurements for both passenger and freight vehicles were analyzed under traffic conditions. The results confirm a clear relationship between pavement quality and vehicle speed. Based on this, a threshold-based algorithm is proposed. It recommends that the minimum speed differential between freight and passenger vehicles should be at least 15% of the passenger vehicle speed, and that the speed reduction caused by pavement degradation should not exceed 15% of the design speed. These findings support traffic management policies and timely maintenance planning to improve road performance and user satisfaction.