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13 CHAPTER 3 Research to Fill Critical Gaps From the gaps identified in Chapter 2, the research team moving freight, requires information on the nature of truck identified research topics that would represent an advance in tours, particularly the number of stops, the average imped- the state of freight modeling in the short term, be consistent ance between stops (e.g., time), and the nature of the land use with the topics identified throughout the outreach process, at each stop on the tour. Many truck fleet operators subscribe and could utilize available data sources. At the research panel's to GPS services provided by vendors that collect and electron- direction, the freight model research considered for this proj- ically distribute the GPS information provided by trucks ect concentrates on short-term model application improve- equipped with units they sell. Although their business model ments (rather than completely new methods). Other research is to provide GPS information to truck fleet operators, many efforts, such as the Strategic Highway Research Program vendors currently store the historical GPS information, and in (SHRP) 2 C20 Project on freight model improvement, will all cases it would be easy to store these data. It should be pos- consider long-term model improvements to develop over the sible to process the historic GPS information to obtain better next 10 years or more. truck trip chaining data. From the list of research topics developed by the research team, the research panel selected the following three topics that address critical gaps in existing freight demand models: Temporal and Seasonal Impacts The methods to collect GPS data discussed above include the Chaining of freight activities, ability to identify the time of day at which a truck stops and Temporal and seasonal impacts, and starts its trips. This information could be used to develop time- Modal diversion consistent with the geographies of public of-day allocation tables for a number of urban areas. These agencies. allocations may be borrowed for use in other urban models, or the GPS methods developed may be used to develop or update The selected topics would develop transferable parameters truck time-of-day allocation tables for models that consider for models that can then be applied to various settings. They time of day assignments. Additionally, the GPS information also are intended to identify techniques for quickly and in- could be used to determine the behavior of specific types of expensively developing model parameters that could be trucks (e.g., long-haul trucks). It has been observed that long- employed by others who might be developing or applying haul trucks may make intermediate stops in urban areas to rest freight models to support public decision-making. Although during congested time periods, or to wait until loading docks this section focuses on the three topics selected for further or port states are open to receive trucks. Documentation of this research, it also includes a discussion of why the remaining behavior and the intermediate stop locations could improve topics were not recommended for advancement. the time-of-day response of urban models. The seasonal movement of freight could be addressed by 3.1 Topics Selected for using information on the monthly flow of trucks from state Further Research weigh in motion stations, border crossings, and FHWA's Vehicle Travel Information System (VTRIS). Although this Chaining of Freight Activities information does not provide any information about the Chaining of freight activities could be addressed by use of commodities carried by these trucks, the FHWA's Freight GPS data. Trip chaining of commercial trucks, including those Analysis Framework, Version 2 (FAF2), Highway Link and