EFFECT OF POSTED SPEED LIMIT ON DRIVERS’ BEHAVIOUR ON URBAN ROADS

Abstract

The setting of speed limits is mostly based on improving the safety and efficiency of vehicle movement, reducing travel time and accident rates on an urban road, but the fuel consumption and emission of air pollutants aren't taken into consideration. The 85th percentile of free flow is commonly used to evaluate a driver's behaviour on urban roads. This research aims to determine the effect of posted speed limit (PSL) signs on speed distribution and violation. Also, to study the influence of dual PSL on the extent of speed violation with respect to vehicle type and speed limit. Additionally, vehicle speed impacts fuel consumption and the emission of air pollutants on urban roads in three cities. In Delhi, Thiruvananthapuram, and Vishakhapatnam, free-flow speed data were collected on urban roads near and away from posted speed limits. Based on the findings, two-wheelers dominate traffic composition in Thiruvananthapuram, followed by cars, trucks, and buses, while cars dominate in Delhi and Vishakhapatnam. Speeds are only reduced by 5–10% by posting speed limit signs; they are less effective at reducing vehicle speeds. The effect of speed on fuel consumption was examined and showed a non-linear relationship. Optimal speed ranges for minimising fuel consumption vary by vehicle type. Smaller vehicles are more fuel-efficient than larger ones. Optimizing speed and driving practices can reduce emissions and fuel efficiency, while also improving traffic safety, fuel consumption, and emissions. Keyword: Speed limit, 85th percentile speed, speed compliances, optimum fuel consumption and emission