Improving exhaust emission evaluation: An integrated modelling approach for urban road networks in diverse operating environments

Motorized vehicle operation stands as a significant contributor to urban air pollution, necessitating immediate attention to prevent its adverse impacts on human mortality and morbidity. However, estimating traffic emissions at a local scale in developing countries is challenging due to heterogeneous traffic conditions. This study proposes an integrated modelling framework called VISSIM-MOVES Integration Model for Delhi City (VMIMD), designated to assess emissions from the congested road network in Delhi's central business district. In addition, the study revises the default emission inventory of the MOVES model by applying correction factors (CFs) developed during the study. These CFs are tailored to address heterogeneous traffic conditions typical of developing nations like India. The application of the CFs has significantly enhanced the overall efficiency of the model for Indian conditions. The study's findings indicate a significant correlation between the duration vehicles spend in different operating conditions (idle, cruise, and braking) and the emission generation. Notably, during heavy traffic hours, emission increases significantly as vehicles reduce their speed and require higher power to transition between different operating modes. The study also includes a comparison between the emissions estimated by VMIMD and emission standards. The results indicate significant differences in emissions, especially during peak traffic hours.