The purpose of this literature review is to assess recent and current literature relevant to the treatment of commercial vehicles in urban transportation models. This literature review includes published literature, unpublished literature, information from the Internet, GIS and survey data sources and internal project documents on related topics.
To date, most of the literature on this topic revolves around urban freight distribution. The state of the practice in the modeling of commercial vehicle travel in the urban transportation context has been geared toward developing a limited number of commercial vehicle trip generation factors, typically only disaggregated by truck type; for example, light, medium and heavy trucks. The traditional approach of relating these rates to land use activity has been found to be limited for application in travel demand modeling due to lack of data on differences in trip purpose, vehicle occupancy, and origin-destination (O-D) patterns. Other definitions of commercial vehicles rely on vehicle registration classifications.
To clarify the scope of the literature review, 13 categories of commercial vehicles were defined and included both individually and categorically in the literature review. Initial reviews on commercial vehicles in general uncovered very few sources in the literature, so the majority of the literature review was focused on individual vehicle types.
In addition, the literature review was focused on trips within an urban area (intraregional trips) rather than on trips entering or leaving an urban area (interregional trips). This is a critical distinction for urban freight trips, where much of the current literature covers interregional freight distribution rather than intraregional freight distribution. This distinction is expected to carry forward in the development of methods for estimating commercial vehicle traffic, where the interregional traffic is estimated using different techniques related to external traffic than intraregional traffic, which is estimated using more specific methods related to trip purpose, demographics and other characteristics of the region.
The approach to the literature review included separately commercial vehicles into individual types of vehicles so that individual searches could be performed. Initial literature searches indicated that this would be necessary to obtain information on some of the less studied types of commercial vehicles. The original 13 categories of commercial vehicles were identified and defined according to the type of service and purpose, and are presented in Table 1.1.
| Vehicle Type | Purpose | Service Type |
|---|---|---|
| 1. School Buses | Movement of People | Fixed Route Service |
| 2. Fixed Shuttle Services at Airports, Stations, etc. | Movement of People | Fixed Route Service |
| 3. Private Transportation: Taxi, Limos, Shuttles | Movement of People | On-Demand Service |
| 4. Paratransit: Social Services, Church Buses | Movement of People | On-Demand Service |
| 5. Rental Cars | Movement of People | On-Demand Service |
| 6. Package and Mail Delivery; USPS, UPS, FedEx | Movement of People | Fixed Route Service |
| 7. Urban Freight Distribution, Warehouse Deliveries | Movement of People | On-Demand Service |
| 8. Product and Package Deliveries | Movement of People | On-Demand Service |
| 9. Construction Transport | Movement of People | On-Demand Service |
| 10. Public Utilities, Trash, Meter Readers, Maintenance | Services | Fixed Route Service |
| 11. Public Safety: Police, Fire, Bldg. Inspections, Tow Trucks | Services | On-Demand Service |
| 12. Trades and Services: Plumbers, Electricians, etc. | Services | On-Demand Service |
| 13. Outside Sales: Realtors, Door-to-Door Sales, Public Relations | Services | On-Demand Service |
General literature searches on the state of the practice models, data sources and modeling approaches were also conducted. Some of the information supporting these general categories were derived from the individual searches and were supplemented by more general literature or data found.
The literature review provides an overview of the information found on state of the practice techniques in Section 2.0, on data sources in Section 3.0 and on modeling approaches in Section 4.0. The report also provides more detailed information on the individual literature reviews for each commercial vehicle type in Section 5.0.
There are two appendices providing reference and supporting information. Appendix A contains all references from the report. Appendix B contains an overview of the information in individual references to address the following questions:
