On-road emission models are used as planning tools in various settings. For example, metropolitan planning organizations (MPO), achieving conformity for the air quality plan, state air agencies working on state implementation plan, state department of transportation working on National Environmental Policy Act (NEPA) analysis, etc. The two pieces of puzzle for estimating emissions are vehicle miles of travel (VMT) and emission factors. The presentation will focus on how VMT and emission factors are developed using travel demand models and emissions model respectively. The presentation will also identify the importance of using local data such as age distribution, meteorology, fuel, inspection and maintenance, ramp fraction, road type distribution, source type population, vehicle miles of travel mix, etc. to develop emissions. Finally, presentation will show examples of how link-level emission estimates can be employed in real world applications.