Impact of Modern Roundabouts on Vehicular Emissions

Vehicular emissions have increased considerably over the years with the increase in traffic. Modern roundabouts can improve traffic flow as well as cut down vehicular emissions and fuel consumption by reducing the vehicle idle time at intersections and thereby creating a positive impact on the environment. The primary focus of this research is to study the impact of modern roundabouts in cutting down vehicular emissions. Six sites with different traffic volume ranges, where a modern roundabout has replaced Stop controlled intersection, have been chosen for the study. The operation of the roadways at the intersection was videotaped and the traffic flow data was extracted from these tapes and analyzed using Signalized and Unsignalized Intersection Design and Research Aid (SIDRA) software. The version used is a.a. SIDRA 2.0. The software produces many measures of effectiveness (MOEs) of which five were chosen for analyzing the environmental impact of roundabouts. The chosen five outputs give rate of emission of HC, CO, NOX, and CO2 in (kg/hr). All the MOEs were statistically compared to determine which intersection control performed better. After comparing all the MOEs at all locations for the before and after traffic volumes, it was found that the modern roundabout performed better than the existing intersection control (i.e., stop signs) in cutting down vehicular emissions thereby creating a positive impact on the environment. The research concludes that a modern roundabout can be used, as a viable alternative to cut down vehicular emissions and thereby making intersections more environment friendly.