NCHRP 08-43 [Final]
Methods for Forecasting Statewide Freight Movements and Related Performance Measures
| Project Data
||Daniel F. Beagan|
Background: According to the U.S. Department of Transportation, the volume of freight moved within the United States has nearly doubled the rate of population increase over the past three decades. In those years, this volume has also outstripped the annualized rates of growth in disposable income and gross national product. The 1997 Commodity Flow Survey, by the Bureau of the Census, found that more than 11 billion tons of freight, valued at almost $7 trillion, moves annually over the nation's transportation system. In calendar year 1997, there was nearly 3 trillion ton-miles of annual freight activity. All of this activity places growing pressure on each state's transportation infrastructure, leading to many costly traffic congestion problems--notably around major airports, seaports, and truck-rail transfer terminals. The increase in the number of trucks is also changing the traffic flow characteristics on some highways, especially as they approach their design capacities. Significant changes have also been taking place in the spatial patterns and commodity mix of both domestic and international trade. Modern logistic practices and the rapid growth in e-commerce are now also influencing these patterns.
Within this highly dynamic environment, a growing number of states are exploring or developing performance measures to gauge how well their transportation systems are meeting the needs of state and local economies, with a focus on goods movement. Examples of performance measures include travel times to national and international markets, congestion costs and delay times at freight bottleneck areas, shipment costs per mile, and benefits and costs to the freight sector from major state-supported transportation facilities.
To address these and similar issues, analytic methods are needed to help states to (a) determine where and how much current freight activity is taking place within and across their borders, (b) forecast future mode- and commodity-specific freight movement patterns, and (c) establish and apply suitable performance measures to evaluate their effectiveness in accommodating freight demand. These tools and methodologies for individual states need to be upwardly compatible so that they can be assembled to form multistate, sub-state, and regional data and information snapshots. To do these tasks effectively, states need better methods for forecasting facility-specific traffic volumes and for analyzing the role that multimodal freight movements can play in getting the most cost-effective use out of different combinations of statewide highway, rail, water, and air freight transport networks.
Currently, there exist numerous gaps in the data needed to estimate the necessary origin-to-destination (O-D) freight movements. This is especially true in the case of truck-only, as well as truck-inclusive, freight movements. Collection and analysis methods are needed to fill these data gaps, to use the resulting O-D volumes to estimate freight flows on specific sections of a state's multimodal transportation network, and to forecast O-D freight movement patterns. These patterns include freight movements both within and between metropolitan areas and crossing state borders.
Objective: The objective of this project was to develop an analytical framework for forecasting freight movements at the state level. This framework includes (1) a tool kit of data collection techniques, analytical procedures, and computer models; (2) management approaches and decisionmaking procedures; and (3) performance evaluation methods that can guide states in establishing priorities for improving their transportation systems to best accommodate increase freight demand.
Tasks: Accomplishment of the project objective required the following tasks.
(1.) Critically review the state of the practice as documented in relevant research, literature, state DOT and MPO procedure documents, and information developed by the FHWA and others. Emphasis was to be placed on evaluation of the effectiveness of current freight-forecasting methods.
(2.) Survey current state needs for and applications of freight movement forecasting.
(3.) Assessment of the state of the practice in base-year data and freight forecasts.
a) Evaluated the limitations and quality of base-year data and determine which base-year data elements can reliably be used for forecasting. Any differences between base-year data and future-year forecasts were to be clearly explained. A clear discussion of data was to include the assessment of strengths and weaknesses, ways to review data for errors, and prescriptive ways to ensure better data. This review specifically addressed the quality of truck vehicle miles traveled (VMT) data and forecasts.
(4.) An interim report was prepared that documented the work performed in Tasks 1 through 3 and recommended necessary revisions to the work plan for the remaining project tasks. Presented the interim report at a meeting with the NCHRP project panel.
b) Evaluated the suitability of alternative analytical methods for creating freight O-D information and recommended the most appropriate methods. Understanding that new methods are available for nationwide freight analysis, this research examined and recommended methodologies for disaggregating national data to be useful at the state level.
(5.) Developed an analytical tool kit that can be used by state DOT planners. This tool kit is intended to provide freight forecasting techniques based on the best practices review. The tool kit provides options, along with strengths and weaknesses of techniques for addressing freight-forecasting applications that states face, such as:
(6.) Identified significant freight performance issues for states and their metropolitan areas. Documented performance measures states now use, and identified additional performance measures that would facilitate state freight planning. Evaluated the extent to which current freight-forecasting models support agency performance measures and made recommendations for their improvements.
- Demand for statewide multimodal freight movement,
- Regional or multijurisdictional freight movement,
- Specific single mode or multimode corridor analyses, and
- Analyses of projected demand at specific facilities (ports, hubs, or terminals).
(7.) Prepared a final report for dissemination of the research findings and the recommended analytical framework for use by appropriate federal, state, local, and other practitioners. Identified research needs emanating from this project.
Status: The project has been completed. The revised draft final reports have been submitted and the report will be published in the regular NCHRP series.
Product Availability: The Report has been published as NCHRP Report 606 and can be ordered from the TRB Bookstore at www.TRB.org/bookstore.