The Transportation Analysis and Simulation System (TRANSIMS) contains a vehicle emissions module that estimates tailpipe emissions for light and heavy duty vehicles and evaporative emissions for light duty vehicles. It uses as inputs the emissions arrays obtained from the CMEM model. This paper describes and validates the TRANSIMS emission module and compares its emission estimates to on-road emission measurements and other state-of-the-art emission models including the VT-Micro, CMEM, and MOBILE6 models. Thirteen different runs were conducted to compare emissions from field measurements to the trends in emissions obtained form the above-mentioned four models. The results indicate that the TRANSIMS model provides consistent trends of estimated Carbon Monoxide (CO) and Hydrocarbons (HC) with field data, while inconsistent trends of estimated Nitrogen Oxides (NOx). However, the magnitude of emissions estimated by TRANSIMS is closer to the field data than those obtained form the other models; MOBILE6, CMEM, and VT-Micro.