4.1 Sector Description
Onroad mobile sources include emissions from motorized vehicles that normally operate on public roadways. This includes passenger cars, motorcycles, minivans, sport-utility vehicles, light-duty trucks, heavy-duty trucks, and buses. MOVES categorizes vehicles into 13 source type identification (ID) codes shown in Table 4.1. The sector includes emissions generated from parking areas, emissions from short-duration idle during pickups/deliveries, emissions from vehicles when they start, and emissions while the vehicles are moving. The sector also includes “hoteling” emissions, which refers to the time spent idling in a diesel long-haul combination truck during federally mandated rest periods of long-haul trips.
Onroad emissions in the 2023 NEI are comprised of emission estimates calculated based on version 5 of EPA’s MOtor Vehicle Emission Simulator (MOVES5). MOVES5 is run with State, local, and Tribal (S/L/T)-submitted activity data and other MOVES inputs when provided, except for California and tribes, for which the NEI includes submitted emissions. In cases where S/L/T submitted data are not provided, EPA developed default activity based on data from the Federal Highway Administration (FHWA) and other data sources. EPA also developed default data for all other inputs required by MOVES which are used where S/L/T data of sufficient quality are not available.
| Source Type ID | Source Type Name |
|---|---|
| 11 | Motorcycle |
| 21 | Passenger Car |
| 31 | Passenger Truck |
| 32 | Light Commercial Truck |
| 41 | Other Buses |
| 42 | Transit Bus |
| 43 | School Bus |
| 51 | Refuse Truck |
| 52 | Single Unit Short-haul Truck |
| 53 | Single Unit Long-haul Truck |
| 54 | Motor Home |
| 61 | Combination Short-haul Truck |
| 62 | Combination Long-haul Truck |