Investigating the feasibility of dynamic speed limit on Indian highways

Abstract

Speed limits that change as per real time traffic, road, and weather conditions are termed as Dynamic Speed Limits (DSL). Road users are informed of speed limit changes in DSL scheme by electronic signs or Variable Message Signs (VMS) placed above the lanes or side-mounted along highways. In India, most of the highways have static speed limits. The speed limits are kept lower at locations or stretches adjacent to roadside schools, market areas, bus stops and intersections, for enhancing safety of Vulnerable Road Users (VRUs). This causes higher travel time to through traffic while travelling through these stretches. DSL has the potential in reducing the travel time and the variability of speed of vehicles, thus helps in enhancing road safety. The present work investigates the feasibility of DSL on various segments of a typical Indian highway passing through various roadside developments and human activities using cost-benefit analysis. The travel time benefits due to DSL are estimated by comparing the travel times with static and dynamic speed limit conditions. The results indicate that there is a significant amount of saving in aggregate travel time of all vehicles passing through the stretch due to the application of DSL. The benefit cost ratios greater than unity indicated that it is beneficial to deploy DSL on several segments of the highway passing through roadside schools, market areas, bus stops and intersections. The Benefit-Cost Ratio is also used advantageously to prioritize viable locations for deployment of DSL. The findings from the present work are likely to be of interest to policy makers in different developing countries where infrastructure/facilities for VRUs are deficient, road safety is a major concern and speeding is identified as a major problem.