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South Dakota Department of Transportation
Project Synopsis

Title: Review of Travel Demand Forecasting Requirements in the SDDOT
Project Researcher: Charles Schwinger, Bucher, Willis & Ratliff Corp
Project Manager: Hal Rumpca
Research Period: 3/5/2007 - 2/29/2008
Cost: $60,000.00

Problem Statement:Statewide travel demand forecasting addresses numerous planning and design issues including corridor preservation, reconstruction and resurfacing strategies, long range plan development, and route diversion impacts. Research Study SD1999-04 "20-Year Traffic Forecasting Factors" was initiated to document and develop new procedures or processes to enhance the South Dakota Department of Transportations (SDDOT) traffic forecasting capabilities. While the study enhanced traffic forecasting factors based on a county level analysis of business growth, population, and traffic volumes, it did not provide a traffic forecasting model or procedures with trip generation, distribution, and assignment capabilities.

SDDOT currently has a limited number of traffic engineers trained in traffic projections, traffic assignments, and distribution techniques. It therefore relies on consultants to provide this information for corridor studies, site impact studies, and long range planning efforts. The SDDOT Long Range Transportation Plan is over seven yeard old, is based on policy rather than projects, and will need to be updated within the next few years. In addition, freight impacts are not well documented and economic development issues are addressed individually without analyzing traffic pattern changes in the state highway network.

A better understanding of travel patterns within the state will lead to improved highway planning and ultimately to a highway network better suited for South Dakotas economic future. The SDDOT needs the capability to analyze route diversion impacts prior to corridor improvements. The department also needs the ability to analyze the capacity and safety impacts associated with increased or diverted truck travel on state routes due to the introduction of new inter-modal facilities adjacent to highways. A review of department policies, processes, resources and other requirements is needed to determine if a statewide traffic forecasting model should be developed, or if other alternatives that might involve training, additional staff, or consultants could meet its travel demand forecasting needs. Finally, a review of the existing travel demand forecasting process needs to be completed to determine if the forecasted factors accurately reflect traffic volumes for the various functionally classified roadways.

Findings: The purpose of this research study was to evaluate the most appropriate traffic forecasting tool that is most responsive to the needs of the South Dakota Department of Transportation (SDDOT). Like many other state agencies, the SDDOT has to do more with less funding for transportation infrastructure, operation, maintenance, and planning. The traffic forecasting functionality had to be tailored to SDDOT's needs and constraints while maximizing benefits.

The interviews of SDDOT stakeholders strongly emphasized the desire for a better forecasting approach than the current 20-year traffic forecasting procedure. The research team evaluated the uses/ needs of traffic forecasts at SDDOT against the availability of data, budget, and staff. While it is possible to build a statewide travel model (STM) of sketch planning type using available data, the applicability of such a model would fall short of meeting many of the identified uses and needs that are largely project specific. However, building a more robust 4-step STM that would satisfy many of the uses/ needs requires travel behavior data currently unavailable. Considering the advantages and disadvantages, the research team did not recommend a four-step statewide model at this stage. A more practical approach in the short-term is to enhance the current 20-year traffic forecasting procedure, use of GIS and transportation planning software, and staff training in travel demand forecasting. A sketch planning type STM was recommended in the short-medium term together with future enhancements that include a regional model option and 4-step STM for passenger and freight.

Research Objectives:
1  Determine the uses of and benefits of travel demand forecasting on a regional or statewide basis at the SDDOT.
2  Identify the level of travel demand forecasting functionality necessary to meet the needs of the SDDOT.
3  Determine the resources necessary to develop, maintain, and operate SDDOT travel demand forecasting capabilities on a regional or statewide basis.

Research Tasks:
1  Meet with the project's technical panel to review the project scope and work plan.
2  Review and summarize existing research concerning travel demand forecasting for regional and statewide applications, including types of forecasts, methods, and data requirements.
3  Interview managers, traffic engineers, designers, planning staff, and other stakeholders within SDDOT to determine policies, requirements, uses, and benefits of travel demand forecasting.
4  Identify processes and systems in SDDOT and other state agencies that have needs for travel demand forecasting.
5  Review and analyze SDDOT's existing travel demand forecasting process and identify and test a procedure to validate the forecasting factors.
6  Identify the type of economic, demographic, passenger, freight, or other data that could be used to develop regional and statewide travel demand forecasts, as well as the costs and other resources necessary to obtain the data.
7  Prepare a technical memorandum that summarizes the work performed in Tasks 1-6 and provide recommendations on the most efficient process and resource needs to produce travel demand forecasts for the SDDOT. Discuss the costs, benefits, advantages, dis
8  Meet with the technical panel to review the technical memorandum and recommendations.
9  Based on SDDOT concurrence with the recommended travel demand forecasting process, develop a systems requirements document and implementation plan that addresses data collection and management, analytical tools, hardware, software, and necessary trai
10  Meet with the technical panel to review and approve the recommended requirements document and implementation plan.
11  Upon review and approval of the systems requirements and implementation plan by the technical panel, prepare a final report and executive summary of the research methodology, findings, conclusions, and recommendations.
12  Make an executive presentation to the SDDOT Research Review Board at the conclusion of the project.

Documents Available:

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