MOBILE3 is a computer program that calculates emission factors for hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx) from highway motor vehicles. MOBILE3 calculates emission factors for eight individual vehicle types in two regions of the country. The emission estimates depend on various conditions such as ambient temperature, speed, and mileage accrual rates. MOBILE3 will estimate emission factors for any calendar year between 1960 and 2020, inclusive. The 20 most recent model years are considered in operation in each calendar year. MOBILE3 supersedes MOBILE2. Compared to MOBILE2, MOBILE3 incorporates several new options, calculating methodologies, emission factor estimates, emission control regulations, and internal program designs...Software Description: The program is written in the FORTRAN language for implementation on a Amdahl 5860 computer using the Michigan Terminal System (MTS) operating system. 304K bytes of core storage are required to operate the model.