Evaluating traffic emission control policies based on large-scale and real-time data: A case study in central China

The traffic control policies, including Odd and Even (OAE) and One Day Per Week (ODPW), were adopted in Zhengzhou, China. In this study, we use the bottom-up policy evaluation framework to capture the temporal-spatial characteristics of traffic conditions and vehicle emissions under various traffic restriction scenarios. Moreover, we use the street-scale simulation model to evaluate the effectiveness of improving air quality. Results showed that the improvements in traffic conditions led to the emission decrease by about 28.3 % for carbon monoxide (CO), 16.2 % for nitrogen oxide (NOx), 21.3 % for particulate matter (PM2.5), and 23.2 % for total hydrocarbon (THC) under OAE. During ODPW, total vehicle emissions decreased by 14.1 % for CO, 10.2 % for NOx, 13.7 % for PM2.5, and 12.4 % for THC. However, the spatial analysis indicates traffic restrictions could not significantly reduce those emis-sions caused by high traffic volume; besides, buses, middle-duty trucks, and heavy-duty trucks have partly offset the reduction benefit from restrictions. The air quality simulation results reveal no significant concentration decrease of CO and nitrogen dioxide (NO2) in most areas. With the update of vehicles, stricter management of high-emission vehicles, and limited coverage for implementation of policies, the traffic control policies were not as effective as before. The limitations of the restriction policies are gradually prominent, and upgrade policies are urgently needed to contin-uously improve urban air quality in the future.

Automated summary

This study evaluates the traffic control policies, such as Odd and Even (OAE) and One Day Per Week (ODPW), implemented in Zhengzhou, China. The improvements in traffic conditions resulted in significant reductions in emissions, but certain vehicles offset the benefits of the restrictions. The air quality simulation revealed limited decrease in pollutant concentrations. Therefore, stricter measures are needed to continuously improve urban air quality.