Master of Science / Department of Industrial & Manufacturing Systems Engineering / Malgorzata J. Rys / Centerline rumble strips (CLRS) are raised or indented patterns installed in the center of undivided rural two-lane highways. Their main function is to alert drivers who are encroaching or leaving the intended travel lane, by producing vibration and noise when crossed by vehicles’ tires. CLRS have been demonstrated to be an effective way in reducing head on and opposite direction sideswipe on two-lane highways (cross-over accidents). However, there are some disadvantages in their utilization, such as the exterior noise created by the strips, which may disturb residents in the highway vicinity. The objective of this study was to verify if the amount of noise created by CLRS is enough to impact negatively on residences and businesses, and to discover if the mean level of noise created by CLRS is statistically different than the noise generated by vehicles driving over smooth pavement. Two types of vehicles were driven over two different patterns of milled-in CLRS (rectangular and football-shaped) and over smooth asphalt pavement, at two different speeds. Researchers collected the noise levels at three distances 50, 100, and 150 feet, measured orthogonally from the center line, in 8 different open space locations. Results indicate that vehicle type, vehicle speed, pavement type, location and distances affect the levels of noise. In addition, both football and rectangular CLRS produced significantly higher levels of noise as compared to the smooth asphalt pavement. A 15 passenger van produced higher levels of noise in comparison with a sedan. Moreover, lower the vehicle speed, noise levels were lower. At every 50 feet of distance, the noise levels dropped significantly. CLRS do increase levels of noise relative to smooth pavement at distances up to 150 feet.

Doctor of Philosophy / Department of Industrial & Manufacturing Systems Engineering / Malgorzata J. Rys / Centerline rumble strips (CLRS) are effective in preventing cross-over crashes and are promoted in the United States (U.S.) as a low-cost safety measure. However, there may be negative issues and/or concerns that question their use under certain road conditions. This dissertation is the result of studying these issues and concerns to provide guidance to policy makers on future installations of CLRS, based on current good practices and on the results of specific investigations of exterior noise, safety effectiveness, economics, and drivers’ behavior, including their interaction with shoulders and shoulder rumble strips (SRS). From a survey conducted, good practices in the U.S. were summarized. From a before-and-after study of CLRS safety effectiveness, results showed that total correctable crashes were reduced by 29.21%. Crashes involving fatalities and injuries were reduced by 34.05%. Cross-over crashes were reduced by 67.19%, and run-off-the-road crashes were reduced by 19.19%. Both Naïve and Empirical Bayes methods were applied and showed statistically similar results. There was no statistical difference between football shaped and rectangular shaped CLRS. From the external noise study performed, it was found that external noise depends on vehicle speed, type of vehicle, and distance. Both football and rectangular CLRS substantially increased the levels of external noise at distances up to 45 m (150 ft). Therefore, before installing CLRS, the distance from houses or businesses should be considered. A distance of 60 m (200 ft) was recommended as the limit of the potential exterior noise problem area. From a study of drivers’ behavior, the analyzed configurations of rumble strips and shoulder width levels affected vehicular lateral position and speed levels, although speed deviations were not practically significant. The study of safety performance function models provided technical and economical recommendations for installation of CLRS. Overall, this study recommends the installation of CLRS on rural, two-lane, undivided rural roads in Kansas. Both patterns, rectangular and football, currently installed in Kansas have provided crash reductions, which have been reflected in economic benefits for society. Shoulder width and traffic volume should be considered as crash predictors for enhancement of the benefits. Guidelines were recommended for future better applications of CLRS.

The research in this thesis was conducted to investigate the initial stage of passing maneuvers on a rural, two-lane, two-way (RTLTW) highway with centerline rumble strips (CRSs). Four measures of effectiveness were used: (1) number and type of erratic movements by a passing vehicle, (2) number of and time between centerline encroachments of a passing vehicle, (3) gap distance of a passing vehicle, and (4) centerline crossing time. Data were collected for a before-and-after analysis at one site, in Comanche County, Texas. The test section was on US 67 from Comanche, Texas to the county line south of Dublin, Texas. The posted speed limit for this RTLTW highway was 70 mph during the day. CRSs were installed along approximately 15 miles of US 67. Only one test design for CRSs was installed. The design specification was for a CRS to be milled to a 0.5-inch depth, 7-inch length, and 16-inch width. This specification was developed from current state practices throughout the United States. CRSs were installed continuously through passing and no-passing zones, and they were spaced at 24 inches on-centers. Pavement markings were striped over the CRSs. Data were collected using an innovative data collection system developed by the author through the Texas Transportation Institute (TTI). This system was mounted to a four-door sedan, and it consisted of four concealed cameras that recorded the entire passing maneuver around the data collection vehicle. Data were collected at three different speeds during the daytime. The speeds were 55, 60, and 65 mph (15, 10, and 5 mph, respectively, under the posted speed limit). Based on the assessment of the four MOEs, the overall finding of this thesis was that driver performance during the initial phase of passing maneuvers was not negatively impacted after the installation of CRSs on US 67. The caveat is that differences in the weather conditions may have influenced the results. The weather was dry with clear skies at the study site during data collection prior to the installation of CRSs; however, the weather consisted of intermittent rain during the data collection after the installation of CRSs.

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.