Study of influence of lane restrictions on vehicular emissions under heterogeneous traffic flow

This paper presents the findings of a study of motorized two-wheeler emissions under lane restricted and lane-less flow conditions in heterogeneous traffic. Lane restriction is defined as the movement of particular categories of vehicles on specified lanes (dedicated lanes), whereas lane-less flow movements are conditions when vehicles are free to change lanes. This study was conducted on selected mid-block road sections of different lengths in Chennai city, India. In the process of test runs, tailpipe emissions (CO, HC and NO) were measured using a portable gas analyzer at short intervals of time. These data were then synthesized to evaluate the total emissions from the vehicles for each test run. Instantaneous speeds of the vehicles were measured using an optical sensor fixed to the wheel. Consumption of fuel by the test vehicles were also measured using a petrol reading apparatus. Based on the analysis of field data collected specifically for this study, it is concluded that lane restricted flow generally produced reduced levels of tailpipe emissions compared to lane-less conditions. The impact of various factors such as, number of lane changes, average speed and fuel consumed on emissions were also studied. In order to understand the relationships between emissions and various traffic factors, regression models were tested and built using SPSS software. Highly heterogeneous traffic conditions and the lane changing behavior of drivers in traffic conditions prevailing in urban areas in India offered unique research opportunities in this study. Copyright ASCE 2008.