BACKGROUND

Rumble strips are proven safety countermeasures for roadway departure crashes as they produce vibration and noise to alert drivers that they are drifting from the travel lane. Neighborhoods who reside roadways with rumble strips often complain about the noise generated by these appurtenances. This issue has prompted a need to simultaneously study noise mitigation and rumble strip design and application. Preliminary studies by state departments of transportation (DOTs) indicate significant potential for sinusoidal rumble strips to provide adequate alerting noise and vibration for the driver while significantly reducing exterior noise. While NCHRP Report 641: Guidance for the Design and Application of Shoulder and Centerline Rumble Strips, showed commendable crash reductions for traditional milled rumble strips, with dimensions of approximately 7x12 inches and ½ inch depth, other designs have been used extensively by several state DOTs to address pavement width or bicycle accommodation issues without documentation of their comparative safety effects or noise impacts. Other states are exploring the effectiveness and appropriateness of various low-noise designs (e.g., varying widths, depths, and shapes).

While there have been a few independent studies of the noise associated with various rumble strip designs, these studies are difficult to compare (e.g., different vehicle types, acoustical equipment and procedures, and rumble strip designs). Due to the scope of the issue, expertise from both transportation safety and noise professionals are required to study noise generated by rumble strips. Providing state, local, and federal agencies with recommendations for rumble strip designs that offer adequate alerting driver feedback and reduced external noise could potentially increase their use and expand opportunities for agencies to reach safety performance goals.

OBJECTIVES 

Under NCHRP Project 15-68(01), “Effective Low-Noise Rumble Strips,” Illington & Rodkin, Inc. was asked to (1) identify or design and evaluate alternative rumble strips that provide effective alerting noise and vibration within vehicles and minimize perceived external noise, while considering several variables (e.g., vehicle types, pavement types, and speed); (2) recommend low-noise rumble strip designs that accommodate all users; and (3) develop recommendations for standard testing and measurement protocols.

STATUS: In addition to the final report published as NCHRP Research Report 1107, a number of appendices are available on the TRB website at trb.org by searching for NCHRP Research Report 1107.