The National Academies

NCHRP 03-41(2) [Completed]

Effectiveness and Implementability of Procedures for Work Zone Speed Limits

  Project Data
Funds: $200,000
Research Agency: Graham-Migletz Enterprises, Inc.
Principal Investigator: James Migletz
Effective Date: 1/1/1994
Completion Date: 3/31/1997

NCHRP Project 3-41, Procedure for Work Zone Speed Limits, developed a new procedure for setting work zone speed limits based on engineering factors associated with particular work zones. In general, the procedure discourages reductions in the speed limit in work zones when no active work is underway or when all work is on the shoulder or roadside. The procedure suggests that when work is underway in or near the traveled way, a reduction of 10 mph in the work zone speed limit may be justified. Other engineering factors, such as the presence of unprotected workers near the traveled way for extended periods, may also justify a 10-mph speed limit reduction. Finally, where physical restrictions require the use of roadway geometrics that require lower design speeds, a speed limit reduction to the design speed of the geometrics is justified, even if this requires a reduction in speed limit larger than 10 mph. While the previous research analyzed traffic operations and safety in work zones to develop the procedure, there is a need to evaluate its effectiveness in actual applications and on a wider scale. These applications need to be assessed in the context of the traffic control treatments used and the range of roadway and environmental situations that are encountered. There is a need to evaluate the potential influence of work zone speed control treatments to provide a sounder basis for the application of the procedure. It is also necessary to assess the implementability of the procedure to determine how well it meets the full range of needs of highway agencies and to identify institutional, legal, and practical constraints to its use.

The objectives of the research are to (1) assess the implementability of the procedure for setting work zone speed limits, (2) document the effect on vehicle speeds where the speed limits are established with the new procedure, (3) make recommendations to refine and extend the procedure as appropriate, and (4) prepare guidelines to facilitate the implementation of the procedure. To accomplish these objectives, the following tasks are envisioned: (1) Contact transportation agencies to solicit feedback on the perceived feasibility of the procedure for a range of conditions. Visit selected states to observe their processes for setting work zone speed limits and selecting traffic control methods. (2) Identify at least 4 highway agencies from different regions willing to participate in field tests of the new work zone speed limit procedure. Work with each agency to develop a plan for implementing the new work zone speed limit procedure for selected projects which reflect different highway types, traffic control treatments, traffic volumes, and other factors. (3) Prepare an interim report that summarizes the initial findings for panel review. Meet with the panel to finalize plans for the field tests. (4) Implement the procedure in the selected agencies, documenting the methods used and the difficulties encountered in accordance with the approved plan. (5) Conduct evaluations of the work zone speed compliance in accordance with the plan approved. Document the traffic speed data collected upstream of and within selected work zones to reflect the level of motorist compliance with the prescribed speed limits. (6) Recommend appropriate modifications to the work zone speed limit procedure and range of situations to which it can be applied based on application experience. Prepare guidelines to facilitate the implementation of the procedure by highway agencies. (7) Prepare a final report that documents the findings of the research.

Status: The research is complete and the contractor's final report is available.

Product Availability: The contractor's final report is available on request from the NCHRP. Efforts to adopt the procedure as part of Manual of Uniform Traffic Control Devices are being continued by the National Committee on Uniform Traffic Control Devices.

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