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5 CHAPTER ONE INTRODUCTION Statewide travel forecasting models address numerous There are data opportunities for statewide models that planning needs by estimating, for a future date, the num- are not available for urban models, such as freight flow ber of vehicles that use major transportation facilities databases and economic forecasts for subareas. within a state. Statewide models can encompass both pas- senger and freight issues, and provide forecasts for a vari- Statewide travel forecasting models seek to determine the ety of modes including highways, urban transit systems, amount and location of travel by looking at parts of the traveler intercity passenger services, airports, seaports, and rail- decision processes. A model based on behavioral principles roads. Statewide models are particularly useful for fore- would differ substantially from one based entirely on empirical casting in rural areas that are not covered by urban travel findings, such as growth factor methods. Nonetheless, some forecasting models. Statewide models provide a consistent states feel that purely empirical models still meet their needs. way to forecast travel on transportation facilities across a state in a manner that reflects current understanding of travel behavior. MAJOR SOURCES OF INFORMATION ON STATEWIDE TRAVEL FORECASTING MODELS Only about half of the 50 states have created statewide There are few general sources of information on statewide or models. Most of these models resemble urban transportation intercity passenger components; however, there have been planning (UTP) models in structure. However, almost all two significant NCHRP studies on statewide freight model- states with models have faced unusual challenges resulting ing. This section highlights important historical and recent from the large sizes respective of their geographic areas and documents that have been useful to individuals or groups the large amounts of data required to adequately describe building statewide travel forecasting models. these areas. With few exceptions, several characteristics of statewide planning demonstrate the need for distinguishing Appendix C is an excerpt from the literature review sec- between statewide and urban models. tion of the Guidebook on Statewide Travel Forecasting (Horowitz 1999) that concerns passenger and intercity travel Statewide models cover far more land area than urban forecasting. Appendix D is an annotated bibliography of the models within the same state. statewide and national freight forecasting techniques. Refer- Statewide models cover far more facilities than urban ences to the literature found in this section are intended to up- models within the same state. date these earlier literature reviews. Statewide models are often concerned with economic developments that extend well beyond the borders of a Guidebook on Statewide Travel Forecasting region, such as national and international trade issues 1999 and trends. There is less experience with statewide models than ur- The Guidebook (Horowitz 1999) was the last major reference ban models. that covered both passenger and freight components of There is less research on intercity travel patterns than statewide models. This resource contains extensive advice on on urban travel patterns. individual steps within the models, network preparation, and Statewide models must incorporate long distance, mul- data sources. A comprehensive literature review and several tiday trips. short case studies are included in an appendix. One chapter is Statewide freight components require recognition of devoted entirely to time series methods such as BoxJenkins many modes, whereas most urban freight components techniques. only focus on trucks. Software products do not address the special needs of The Guidebook emphasizes three- or four-step modeling statewide models. approaches. Details are given on how urban transportation mod- The legal impetus for statewide models is insufficient eling software packages could be adapted for statewide models. when compared with metropolitan planning organization It recommends that freight forecasting be commodity-based, (MPO) models. although there was some treatment of truck-only models.

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6 The Guidebook does not include discussions of two completed by many of the representatives. States reporting on emerging topics: tour-based passenger components and com- their models were Florida, Indiana, Kentucky, Louisiana, bining freight and passenger components with a built-in eco- Massachusetts, Missouri, New Hampshire, New Jersey, Ohio, nomic activity component. Oregon, Virginia, and Wisconsin. The proceedings of the Peer Exchange have been published by TRB as Transportation Research Circular E-C075. Transportation Research Circular E-C011: Statewide Travel Demand Forecasting (Conference Proceedings) 1999 Presentations at the 2004 Annual Meeting of the Transportation Research Board, Session on This specialty conference, roughly coinciding time-wise Statewide Travel Forecasting Models with the publication of the Guidebook, heard reports from several states about their existing statewide models and plans This session involved presentations by six authors on new for new statewide models. Breakout sessions also provided developments in statewide travel forecasting models. research recommendations. Presentations were made by rep- resentatives from California, Florida, Indiana, Kentucky, Ohio Statewide Travel Demand Forecasting Model Michigan, New Hampshire, New Jersey, Oregon. Rhode An update on the Transportation and Land Use Model Island, Washington, and Wisconsin. Information Project (TLUMIP) in Oregon Wisconsin Statewide Model Statewide Modeling: The New Frontier NCHRP Report 260: Application of Statewide The Trouble with Intercity Travel Demand Models Freight Demand Forecasting Techniques 1983 A Brief Synthesis of the State of the Practice in Statewide This report (Memmott 1983) provided a methodology for Travel Forecasting. building a freight component for a statewide model. The re- port recommended a commodity-based approach and sug- The PowerPoint slides can be found on the Statewide gested that commodity distribution be performed by a gravity Travel Forecasting website: http://www.uwm.edu/~horowitz/ expression. An all-or-nothing mode-split step was proposed. statewide.html. Modal costs were to be determined with the help of regulated tariffs then in effect. The location of commodity consumption On-Line Documents About Statewide Travel was to be determined by an inputoutput (IO) model. Forecasting Models Numerous states or their consultants have web pages that NCHRP Report 8-43, Methods for Forecasting contain documents about their statewide travel forecasting Statewide Freight Movements and Related Performances 2005 models. These web pages are volatile, and a fresh web search is required to find the most current information. Here are a This draft report (Cambridge Systematics, Inc., et al. 2005) few web pages that were active at the time of this report. is a comprehensive reference on the current state of the prac- tice in statewide freight forecasting models. It describes sev- Florida Statewide Freight Model: webservices. eral approaches to model building, depending on project camsys.com/freightmodel/freightmodel.htm. needs and data availability, including the direct facility flow Vermont Statewide Model: http://www.aot.state.vt.us/ factoring method, origindestination (OD) factoring method, planning/TDModel.htm. truck model, four-step commodity model, and economic ac- Virginia Statewide Model: http://www.wilbursmith.com/ tivity model. Ten case studies of freight components are pre- vdotmodel/howandwhen.html. sented: Minnesota Trunk Highway 10 truck trips, Florida Virginia Statewide Freight Model: http://www.wilbur ports, Ohio's interim freight component, FHWA's Freight smith.com/vdotmodel/attachments/082902/Freight% Analysis Framework (FAF), New Jersey truck trip table, 20Report%20(Draft%2008-20-02).pdf. Southern California Association of Governments heavy-duty Ohio Statewide Model: http://www.dot.state.oh.us/ trucks, Indiana commodity transport, Florida statewide urban/AboutUs/Statewide.htm. freight, Cross-Cascades Corridor Analysis Project, and Ore- Connecticut Statewide Model: http://www.ct.gov/dot/ gon combined passenger and freight. cwp/view.asp?a=1383&q=259806. Oregon Statewide Model: http://www.oregon.gov/ ODOT/TD/TP/TMR.shtml. Statewide Travel Demand Models Peer Exchange 2004 Quick Response Freight Manual 1996 The attendees of the Peer Exchange (Longboat Key, Florida, September 2324, 2004) included representatives from 14 Although not specifically for statewide models, the Quick states and consultants who reported on their statewide model- Response Freight Manual (QRFM) (Cambridge Systematics, ing efforts. The proceedings are distilled from a questionnaire Inc., et al. 1996) (Travel Model Improvement Program,