Hossein Shahbazi - Mechanical Engineering Department, Sharif University of Technology, Tehran, Iran
Rouhollah Ganjiazad - Mechanical Engineering Department, Sharif University of Technology, Tehran, Iran
Vahid Hosseini - Mechanical Engineering Department, Sharif University of Technology, Tehran, Iran
Masoud Hamedi - Mechanical Engineering Department, Sharif University of Technology, Tehran, Iran

This Tehran air quality, due to its dangerously high level of pollutants, is a serious concern. Several immediate and emergency solutions are pursued to mitigate the problem in the short term. Most of the solutions are based on traffic restriction schemes that pose challenges to the citizen’s mobility. As part of such policies, central part of the city is converted into a Traffic Restricted Zone (TRZ) in which vehicles are allowed to enter the zone only in certain days of the week based on their license plate number. The purpose of this study is to investigate the effectiveness of such policy on reducing various pollutants concentrations by using advance air quality modelling approach. First, the pollutant emissions are calculated by the International Vehicle Emissions (IVE) model, and then the results are used in WRF/CAMx modelling system to investigate effects of traffic restriction enforcement policy on the air quality and pollutant dispersion over Tehran. Measured data at monitoring sites were used to benchmark performance of the modelling system. The results show satisfactory performance for both models in predicting meteorological parameters and concentration of pollutants. While emission input data was reduced by 40% in the TRZ, the maximum reduction in CO as a primary pollutant was approximately 20% which is highly related to the traffic conditions. Results suggest that effectiveness of TRZ policies highly depends on the type of pollutant, meteorological conditions, and the location of study area

Traffic restriction, Emission inventory, Traffic policy evaluation, Air quality modelling