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The National Academies

NCHRP 17-32 [Completed]

Guidance for the Design and Application of Shoulder and Centerline Rumble Strips

  Project Data
Funds: $600,000
Research Agency: Midwest Research Institute
Principal Investigator: Darren J. Torbic
Effective Date: 6/10/2005
Completion Date: 3/31/2009

BACKGROUND

Shoulder rumble strips have demonstrated effectiveness in reducing lane-departure crashes on rural freeways. Because they have proven to be cost-effective countermeasures, state DOTs and local agencies want to expand the use of rumble strips along the shoulders of divided and undivided highways and along the centerline of undivided highways including 2-lane roadways. However, installing rumble strips to reduce run-off-the-road or centerline crossover crashes, with no consideration of impacts to other users, may lead to unintended outcomes.

Some of the unresolved issues with installing either centerline or shoulder rumble strips include
  • Minimum dimensions of the rumble strips necessary for effective vehicular warning with least potential for adverse effects;
  • Optimal placement, including minimum criteria for lane and shoulder widths;
  • Optimal longitudinal gaps in rumble strips to provide accessibility for cyclists while maintaining the effectiveness in reducing lane departures;
  • Effectiveness and alternative designs for various speeds;
  • Physical design of rumble strips with respect to "rideability" for motorcyclists and bicyclists; and
  • Noise produced by rumble strips on adjacent residents.

The shoulders of the highway system are a diverse environment, with usage by bicyclists, pedestrians, mail carriers, school buses, and farm vehicles. There is great variability in shoulder widths, materials, and pavement depths, making uniform application difficult. The optimal placement of the rumble strips in relation to the shoulder stripe is also in question. Further, shoulders are used for lane shifts during construction and maintenance operations, requiring vehicles to drive over the rumble strips resulting in driver discomfort and potential operational problems.

Although information is limited, there is evidence that centerline rumble strips are an effective countermeasure for reducing centerline crossover collisions. However, centerline rumble strips have specific concerns regarding pavement durability at centerline joints, their use in passing zones, and their impact on motorcyclists.

Research is needed to provide guidance on the appropriate application of rumble strips on undivided and divided highways in urban and rural areas. It is important that designers have full knowledge of the impacts, so that the benefits are maximized while minimizing unintended effects.

OBJECTIVE

The objective of this project is to develop guidance for the design and application of shoulder and centerline rumble strips as an effective motor vehicle crash reduction measure while minimizing adverse operational effects for cyclists and adjacent property owners.

Accomplishment of the project objective will require at least the following tasks.

TASKS (1.) Conduct a literature review of completed and ongoing studies on shoulder and centerline rumble strips. This should also include a critical review of prior safety evaluations. (2.) Conduct a survey of state and Canadian provincial transportation agencies to identify existing policies/guidelines governing the design and installation of shoulder and centerline rumble strips on rural and urban highways. As a minimum, the survey should identify rumble strip design, placement, and application with respect to the edgeline/centerline, traffic volume, crash history, posted speed, pavement type, presence of a designated bicycle route, spacing, and geometric configuration of the roadway. The survey should identify sources of data to quantify the effectiveness in reducing run-off-the-road and cross centerline crashes. Completed and ongoing studies should also be identified. (3.) Submit an interim report documenting the results of Tasks 1 and 2. As a minimum, the report shall include
  • The state of practice in regard to rumble strips,
  • Recommended practices based on the available information,
  • Identification of issues that remain to be resolved through research, and
  • A revised work plan, including an experimental design to address unresolved issues.

(4.) Meet in Washington D.C. with the NCHRP panel to review the Task 3 interim report, including the revised work plan, approximately 1 month after its submittal. After the meeting, submit a revised interim report addressing the review comments and decisions at the meeting. (5.) Execute the approved work plan. (6.) Prepare a second interim report that documents the research effort to date, including Tasks 1 through 5 (7) Execute additional work plans approved by the project panel. (8) Submit a final report documenting the entire research effort. The final report shall describe how the project was conducted and include, as an appendix, the guidance document.

Status: The project has been completed and the revised final report published as NCHRP Report 641.

Product Availability: NCHRP Report 641, "Guidance for the Design and Application of Shoulder and Centerline Rumble Strips." http://www.trb.org/Publications/Blurbs/Guidance_for_the_Design_and_Application_of_Shoulde_162610.aspx

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