An Alternative to Truck Trip Generation Approach for Regions with Unconventional Land Use and Population Patterns

Local and regional transportation agencies, often working in collaboration with consultants, typically use economic, demographic and land use data to develop models that can estimate the flow and direction of truck travel in their region. These models may utilize the Federal Highway Administration's (FHWA’s) Freight Analysis Framework (FAF) as the source of truck trips at the larger freight zone level and then attempt to disaggregate truck trips to smaller levels of geography. However, as a national database, FAF does not always provide accurate results for regions with unconventional land use patterns, and disaggregation models can be difficult to reproduce for future updates. Agencies may also purchase high-resolution proprietary databases (e.g., TRANSEARCH database), typically at the county level, which provide limited information on their methodologies and validations. The approach proposed in this paper was borne out of the need to develop an alternative, transparent, reproducible and easily interpreted methodology for estimating truck trip generation. It utilizes FAF to the extent that FAF categories match with employment categories in the local region, but also relies on surveys, state databases, and other sources of data to estimate truck trip generation rates. These rates can then be multiplied by the number of employees within businesses (classified according to North American Industry Classification System (NAICS) codes) to determine the truck trips at any level of geography. While the application of this truck trip generation approach was intended for the Las Vegas Valley, freight practitioners may find the methodology and approach suitable for truck trip generation in their region as well.