Air quality in congested urban cities has been deteriorating as result of vehicles emissions. Air pollution caused by vehicles emissions has harmful effect on people who are exposed to the polluted air, as well as causing damages to the surrounding environment. Increase in vehicles emissions is caused by a continuous growth in population and car ownership. This study has many objectives. The first is building traffic models using PTV VISSIM and emissions models using COPERT for different corridors as an example to build like these models for Zagazig streets network. These models were built to determine how traffic-related emissions affect the levels and concentrations of CO, NOX, and CO2. In order to reduce traffic congestion and concentrations of the emitted pollutants, several traffic scenarios were simulated and tested. Analyzing modeling results showed that the average traffic speeds were improved for enhancement modifications of traffic compared to current condition. Despite this improvement in the average speed, the total emissions of CO and NOX fluctuated between a decrease for some links and an increase for others. In addition, concentrations of CO decreased to be lower than or nearby World Health Organization (WHO) permitted values. The total amount of CO2 decreased with increasing average speed for these corridors. The average reduction in CO2 emissions with each 1 km/h increase was 94 kg. In this paper, the annual emission costs were also evaluated for all corridors in order to identify the benefits gained from emission decrease and the damage cost from emission rise.