TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 339: Centerline Rumble Strips (CLRS) examines current design, installation, configuration, dimension, and visibility issues associated with CLRS. The report addresses the need for guidance on warrants, benefits, successful practices, and concerns such as external noise and the reduced visibility of centerline striping material. Also addressed are pavement deterioration, ice buildup in the grooves, adverse impact on emergency vehicles, and the effect of CLRS on bicyclists. Particular attention was paid to available before-and-after CLRS installation crash data to document the safety aspects of CLRS and the availability of policies, guidelines, warrants, and costs regarding their use and design.
This report provides guidance for the design and application of shoulder and centerline rumble strips as an effective crash reduction measure, while minimizing adverse effects for motorcyclists, bicyclists, and nearby residents. Using the results of previous studies and the research conducted under this project, safety effectiveness estimates were developed for shoulder rumble strips on rural freeways and rural two-lane roads and for centerline rumble strips on rural and urban two-lane roads.
This report presents an evaluation of centerline rumble strips on a two-lane mountain highway. Accident data before and after construction is given to demonstrate the improvement in safety. Visual evaluations of the effects of the rumble strips on the condition of the pavement and centerline striping are given. Centerline rumble strips are recommended for installation on two-lane highways where there is a history of crossover (head-on and sideswipe from opposite directions) type accidents.
Within the last decade, centerline rumble strips have become increasingly prevalent as a safety countermeasure on undivided roadways throughout the United States. Within the state of Georgia, nearly 200 miles of centerline rumble strips have been installed in an effort to address the severity and frequency of crashes involving the centerline. With several thousands of miles of new installations throughout the nation in the last decade, much literature on this subject is still being amassed. This paper will compile and summarize existing literature in order to provide a thorough overview of the latest information from around the United States regarding the safety, usage, and impacts of centerline rumble strips. Furthermore, this paper seeks to comprehensively determine the safety impacts of centerline rumble strips on undivided, rural highway facilities in the state of Georgia. This portion of the study will prepare an updated inventory of centerline rumble strip installations in Georgia and perform a before-after study using three methods: a direct before-after analysis, a comparison before-after analysis, and a comparative analysis. These analyses will incorporate data from crash databases, police records, and traffic records to produce results unique to Georgia. Lastly, this paper will determine the current status of centerline rumble strips and the potential short- and long-term safety, physical, and unintended effects of centerline rumble strips both in the state of Georgia and throughout the United States through a survey sent to all fifty state transportation agencies. Through literature compilation, safety analyses, and findings on the effects of centerline rumble strips, this paper will aid in the future of centerline rumble strips within Georgia and the United States.
Following the wide and successful use of continuous shoulder rumble strips, many state departments of transportations (DOTs) installed centerline rumble strips (CLRS) on rural two-lane and undivided multilane highways in an effort to reduce cross-over-the-centerline (COCL) crashes. COCL crashes include head-on, sideswipe opposite direction, fixed object run-off-the-road left, and non-collision. The purpose of this research was to develop guidelines for using CLRS in Virginia based on a review of best practices and the analysis of Virginia COCL crash data from 2001 through 2003. The analysis procedures included data query and analyses of crash frequency, density, and rate. Areas and route locations with the highest COCL crashes and densities were identified as potential candidate sites for CLRS. As of 2003, 24 state DOTs and two Canadian provinces were using CLRS. They are generally installed on a case-by-case basis. CLRS design patterns vary greatly among states, but the most commonly used types are continuous grooves 12 to 16 inches in length, 6 to 7 inches in width, and 0.5 inch in depth spaced 12 or 24 inches apart. The optimal CLRS patterns remain unknown. Data analyses revealed that the distribution of COCL crashes in Virginia varied significantly with roadway system, road type, jurisdictional area, and road location. The statewide COCL crash densities were 0.13 and 0.71 crash per mile for secondary and primary roads, respectively. Fixed object run-off-the-road left was the predominant type of COCL crash followed by sideswipe opposite direction and head-on for undivided roads. The crash density of the primary system was 4.5 times higher than that of the secondary system. Guidelines were developed that outline the application of CLRS, design dimensions, installation and maintenance, and other issues. The authors recommend that the Virginia Department of Transportation's Traffic Engineering Division implement the guidelines as a division memorandum. Although a benefit-cost ratio for this recommendation will vary with each site, a sample estimated benefit-cost ratio was at least 7.6 per mile.
This synthesis documents current practices used by states installing rumble strips and explores variations in practice in terms of design, criteria, and locations for installation, maintenance, perceived benefits, communication of benefits, and important issues. Information was acquired through a literature review, survey on current practice, and case examples. The survey also included questions specific to the state of practice for rumble stripes, which is the term used when the pavement marking lines are painted on the rumble strip in an effort to increase visibility during inclement weather conditions. The findings indicate that two-thirds of the state agencies rely on traditional methods to address the noise issue: skipping rumbles in residential areas, adjusting their depth, or not installing rumbles at all. The overwhelming majority of responding states, 83%, have developed policies or guidance to modify their rumble design practices to be sensitive to cyclists. Fewer than half the respondents have developed policies/guidance to address pavement deterioration; several agencies indicated that pavement condition is a factor on whether to install a rumble or not. The survey also showed that very few state DOTs have created public campaigns to explain that the use of rumbles improves safety so that complaints regarding noise, bicycle issues, and other are minimized.
