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Evaluating the Effects of Freeway Rumble Strips on All Crashes


Several previous research efforts have demonstrated that rumble strips reduce single vehicle run-off-road crashes which are the target crashes for that treatment. However, recent research by Wu et al. (2014) indicates that shoulder rumble strip installation has no effect on reducing the probability of the most severe crashes. These researchers examined the effect of rumble strip presence on fatal and major injury crashes of all types (i.e., target plus non-target). A similar trend is found in the freeway predictive method in Chapter 18 of the Highway Safety Manual. When shoulder rumble strips are present, this method predicts a significant reduction in fatal-and-injury crash frequency as a group, but it also predicts a shift in the severity distribution such that there is a slight increase in fatal and major injury crash frequency.

Based on these recent findings, the following questions are being asked, “Have the previous studies overlooked the secondary influence of rumble strips on the non-target crash types”? Is it possible that rumble strip installation increases the frequency of the most severe non-target crashes to the extent that it offsets the well-documented reduction in severe target crash frequency”? Research is needed to examine these questions.

Research by Torbic et al. (2009) indicates that shoulder rumble strip effectiveness varies by facility type (i.e., freeway, multilane highway, two-lane highway) and by area type (i.e., rural, urban); possibly reflecting an indirect effect of speed or roadway lighting presence on rumble strip performance. This same research also indicates that rumble strip effect may vary among states; possibly reflecting an indirect effect of rumble strip design (i.e., milled/rolled and offset from traveled way) on rumble strip performance. The findings from other recent research suggest that shoulder rumble strip effect may vary by alignment location (i.e., curve vs. tangent). It is possible that the recent research findings regarding target-vs-non-target-crashes might be explained by the characteristics of the sites studied and the associated differences in rumble strip design. A research project is needed to identify the factors that influence rumble strip safety effect to ensure that agencies are informed of rumble strip designs that are most effective at improving overall safety.


The objectives of this research are to (1) quantify the effect of shoulder rumble strip presence on both target and non-target crashes at each individual severity level (i.e., fatal, incapacitating injury, non-incapacitating injury, possible injury, and property damage only) and (2) develop models for predicting rumble strip effect as a function of site characteristics such as (but not limited to) facility type, area type, rumble strip design, and alignment location. As a minimum, this research should address freeway facilities given that this facility type has the highest VMT and, thereby, the most potential to benefit from the research results. However, other facility types should also be investigated if possible. The research plan to accomplish these objectives will likely need to include the following activities:

· Identify alternative shoulder rumble strip designs used throughout the U.S.

· Evaluate the impact of shoulder rumble strip presence on target and non-target crashes at each severity level; examine whether the magnitude of the effect is influenced by facility type, area type, rumble strip design, and alignment location

· Develop models for predicting rumble strip effect on crash frequency and severity as a function of influential site characteristics; the models may be represented as crash modification functions

· Recommend best practice for installation of shoulder rumble strips

· Document the proposed predictive models in a format suitable for incorporation in the next edition of the Highway Safety Manual


This study is expected to quantify the effect of shoulder rumble strips on overall highway safety and severity (i.e., both target and non-target crashes at each severity level). The research findings will be used to inform decisions regarding the most cost-effective shoulder rumble strip design and location for specific area and facility types. The findings will be developed and documented in a manner suitable for implementation in the Highway Safety Manual.

Related Research:

· Wu, F., E. Donnell, and J. Aguero-Valverde. “Relating Crash Frequency and Severity: Evaluating the Effectiveness of Shoulder Rumble Strips on Reducing Fatal and Major Injury Crashes.” Accident Analysis and Prevention, Vol. 67, 2014, pp. 86-95.

· FHWA Technical Advisory T 5040.39: Shoulder and Edge Line Rumble Strips, November 7, 2011.

· Torbic, D.J. et al, NCHRP Report 641: Guidance for the Design and Application of Shoulder and Centerline Rumble Strips. National Cooperative Highway Research Program 2009.

· Morena, David A., The Nature and Severity of Drift-Off Road Crashes on Michigan Freeways, and the Effectiveness of Various Shoulder Rumble Strip Designs, Presented at the 82nd Annual Meeting of the Transportation Research Board, 2003.

· Perrillo, Kerry, The Effectiveness and Use of Continuous Shoulder Rumble Strips, Federal Highway Administration, New York, 1998.

· Hickey, John J. Jr., Shoulder Rumble Strip Effectiveness, Drift-Off-Road Accident Reductions on the Pennsylvania Turnpike, Transportation Research Record 1573, 1997.

· Sayed, T., Impact of Rumble Strips on Collision Reduction on British Columbia Highways: A Comprehensive Before and After Safety Study, Transportation Research Record 2148, 2010.

· Carlson, Paul J. et al, Evaluation of Wet-Weather and Contrast Pavement Marking Applications: Final Report, Texas Transportation Institute, 2007.

· Potts, Ingrid B.et al, Benefit-Cost Evaluation of MoDOT's Total Striping and Delineation Program, Midwest Research Institute, 2008.

· Moeur, Richard C., Rumble Strip Gap Study, Final Report, Arizona DOT, 1999.

· USDOT, Policy Statement on Bicycle and Pedestrian Accommodation Regulations and Recommendations, 2010.

· Elefteriadou, L., et al, Bicycle-Friendly Shoulder Rumble Strips, Pennsylvania Transportation Institute, 2000.

· American Association of State Highway and Transportation Officials (AASHTO), Guide for the Development of Bicycle Facilities, Washington, DC, 1999.


Target Audience: Traffic and geometric design professionals responsible for freeways.

Key Decision Makers: State DOT Chief Engineers

AASHTO Committees: The AASHTO Standing Committee on Highway Traffic Safety, Standing Committee on Highways, and Subcommittee on Design could facilitate the implementation of the research results along with Technical Committee on Geometric Design.

Early Adopters: The research results will be easily implementable although various state DOTs who could serve as early adopters to begin using the results. Webinars could be used to help disseminate the research results. There are no known barriers to implementation of the research products.


This research is highly recommended as the use of rumble strips is growing.

Sponsoring Committee:AKD10, Performance Effects on Geometric Design
Research Period:12 - 24 months
Research Priority:High
RNS Developer:Sarah Binkowski, Jim Bonneson, Kay Fitzpatrick, Karen Dixon
Source Info:Developed as part of the 2017 annual meeting of the TRB Committee on Highway Safety Performance (ANB25), TRB Committee on Operational Effects of Geometrics (AHB65), and TRB Committee on Geometric Design (AFB10).
Date Posted:09/21/2018
Date Modified:12/31/2018
Index Terms:Rumble strips, Road shoulders, Freeways, Countermeasures, Crash rates, Highway safety, Crash severity,
Cosponsoring Committees:ACS20, Safety Performance and Analysis
Operations and Traffic Management
Safety and Human Factors

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