A close examination of posted speed limits and its compliance on Indian State Highways

Abstract

Road accident is most unwanted thing to happen on a road. Most of the fatal accidents occur due to over speeding. Increase in speed multiplies the risk of accident and severity of injury during accident. Excess speed is defined as the one exceeding the speed limit and driving at a speed unsuitable for the prevailing road and traffic conditions. Controlling the vehicle speed can prevent crashes happening and can reduce the impact when they do occur. Specified speed limits are of huge importance in controlling the road accidents. Speed limits are the maximum legal travel speeds during favorable conditions. The speed limits provide a balance of collision risk, safety and also provide the basis for enforcement. These limits are set with the goal of keeping everyone safe. Twenty six sections of undivided two-lane and four lane divided interurban State Highways are selected in 03 states of India to analyze the speed data to estimate the level of compliance of posted speed limit sign. Operating speed models are developed for the road sections selected in this study using different parameters. The most influencing parameters are found to be shoulder width (SW), percentage of heavy vehicle (%HV) and road side hazard rating (RSH) for medium traffic two lane State Highways. For heavy traffic four lane divided roads, the most influencing parameter is the percentage of heavy traffic only. The study found that 24.6 to 35.81 percent drivers are travelling above speed limit and few are (1.08 to 1.72%) travelling at speed higher than 98th percentile speed also. Based on the results of speed compliance need speed limits are proposed for these highways.