The National Academies

NCHRP 03-55(2) [Final]

Techniques to Estimate Speeds and Service Volumes for Planning Applications

  Project Data
Funds: $200,000
Research Agency: Dowling Associates
Principal Investigator: Richard G. Dowling
Effective Date: 7/1/1995
Completion Date: 9/30/1996

The Intermodal Surface Transportation Efficiency Act (ISTEA) and the Clean Air Act Amendments (CAAA) have made planning analyses more relevant to national policy issues and concerns. Current techniques for estimating speeds and service volumes are inadequate to meet present transportation planning needs. Research is needed to determine the most appropriate techniques to estimate speeds and service volumes for use throughout a broad range of planning applications.

The objective of this project was to evaluate and recommend modifications and/or alternatives to existing techniques for estimating vehicle speeds and service volumes in planning applications. Techniques were considered for urban and rural as well as interrupted and uninterrupted flow facilities. Techniques for an individual facility (rather than point, corridor, or network techniques) were emphasized, although these techniques are suitable for a systemwide planning analysis.

The research included the following tasks: (1) Review the literature to identify techniques used in estimating speeds and service volumes for planning applications. These applications include long-range planning, air quality conformity, congestion management, growth management, major investment studies, intermodal planning, and national reporting of highway conditions. (2) Design, conduct, and analyze a user survey. Survey recipients should include state departments of transportation (DOTs), metropolitan planning organizations (MPOs), local agencies, and consultants (at least 100 surveys should be distributed). At a minimum, the survey should identify a) techniques currently used and their perceived strengths and weaknesses, b) data easily obtained by the user, and c) most pressing needs to enhance the state of the practice. (3) Assess existing techniques identified in Tasks 1 and 2. Criteria for the assessment include data requirements, ease of use, reliability, user confidence, and general acceptance. Identify significant deficiencies and propose methods to address them. (4) Identify data needed and possible data sources for validation of techniques that are to be developed in Task 6. Simulation data are not acceptable for validation purposes. (5) Prepare an interim report presenting the results of Tasks 1 through 4 and a proposed updated work plan for all remaining tasks. Pay particular attention to identifying the techniques to be developed in Task 6. (6) For applications that lack satisfactory techniques, develop alternative techniques to estimate speeds and service volumes of urban and rural as well as interrupted and uninterrupted flow facilities. No more than three alternatives were developed for each of the four facility types considered. (7) Evaluate the alternative techniques developed in Task 6. Evaluation criteria included data requirements, ease of use, accuracy of results based on the data identified in Task 4, consistency with results obtained from HCM operational analysis, and range of planning applications and facility types addressed by the technique. Recommend the preferred alternative(s). (8) Prepare a final report summarizing the entire research effort. Include a summary of the literature and user surveys, an assessment of existing and newly developed techniques, and a thorough discussion of recommended techniques with sample problems illustrating their application. After receiving comments from the panel, the contractor addressed the comments and revised the report as necessary.

Status: The final report has been published as NCHRP Report 387, Planning Techniques to Estimate Speeds and Service Volumes for Planning Applications.

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