Study On The Vehicles Emissions Of At-grade Intersections Based On Operating Mode

With the rapid speed of urbanization and the ever-growing number of motor vehicles inChina, the pollution from motor vehicles has become one of the pressing challenges to thesustainable development of cities. Meanwhile, road junctions or intersections, where holds agreat proportion of traffic flow and traffic conflict points, are the bottleneck of these problems.As critical nodes of the city traffic network, the traffic at road intersections is frequentlyhalted by traffic signals which leads to more emissions of the by-passing vehicles. To addressthis problem, quantitative evaluation of the traffic flow emissions at road intersections, as afundamental tool of pollution control of the motor vehicles need to be critically analysed andimproved.Based on the new emission modelling system "Motor Vehicle Emission Simulator(MOVES)" and on-site monitoring data, the author has evaluated several measures of trafficflow emission reduction practice. A case study of a typical crossroad located at Xiao Zhai,Xi’an City has been conducted to support the research findings. Having acquired the on-sitemeasurement of the traffic flow and reported meteorological data, Vehicle-Specific Power(VSP) was implemented to characterize traffic conditions in that certain period. Aftermatching the types of the observed vehicles with the classifications of MOVES, anintersection traffic flow emission model was proposed and tested for the condition of greenlight signal and red light signal, respectively. Based on the time weighting of the green lightsignal and red light signal, an emission table has been drawn for the investigated case. Thenthe emissions from the vehicles and its characteristic of temporal and spatial distribution wasanalysed and related to different traffic flow condition and vehicle types. Finally, anevaluation of the emission reduction practice was carried out using the MOVES. Thefindings of the current research have shown that the emission model for road intersectionsproposed can provide reliable and accurate quantitative evaluation of the reduction of theemission and can be used as a supporting technical tool for the improvement of trafficenvironment.