Search

This report describes the methodology and results of analyses performed to (1) evaluate the impact of shoulder rumble strips (SRS) and centerline rumble strips (CRS) on the placement of vehicles in the travel lane of two-lane, undivided roadways and (2) determine the minimum shoulder width required for drivers to correct errant vehicle trajectories once alerted by passing over SRS. Field studies indicated that CRS on twolane, undivided roadways with lane widths as narrow as 10 ft do not adversely impact the lateral placement of the vehicle in the travel lane. In fact, at locations with smaller shoulder widths (1 to 2 ft) drivers positioned the center of their vehicles closer to the center of the lane. Similar effects were found at locations with both edgeline rumble strips (ERS) and CRS. The impact of SRS located within 7 to 9 inches of the edgeline on the lateral placement of vehicles in the travel lane was less clear. However, it does appear that SRS located near the edgeline may shift vehicle travel paths closer to the centerline. In contrast, SRS located 35 inches from the edgeline did not seem to impact the lateral placement of vehicles in the travel lane. In addition, lateral offsets that position the center of 16-inch SRS in the middle of the shoulders at least 4-ft wide should provide enough remaining shoulder width for the 85th percentile distracted driver to correct their errant vehicle trajectory before leaving the paved roadway surface. Additional findings from all of the studies and detailed recommendations are discussed in the report.

The Florida Department of Transportation (FDOT) District 1 office utilized temporary rumble strips on the approach to work zone areas on State Road 31 to alert motorists of lane closures associated with a milling/resurfacing project, from the Lee/Charlotte County line to the Charlotte/Desoto County line. The ability of rumble strips to alert drivers of unusual or hazardous conditions makes them ideal candidates for use on the approach to a highway work zone. In addition to ease-of-use, temporary rumble strips are brightly colored. Thus, temporary rumble strips provide three types of warnings to alert the motorist to the approaching work zone: a physical vibration, an auditory rumble sound, and a visual cue. In addition to making drivers more alert, it is anticipated that temporary rumble strips will impact travel speeds. This report documents the findings and conclusions of a field experiment conducted on State Road 31 at various test (with temporary rumble strips) and control (without temporary rumble strips) locations to determine the effectiveness of temporary rumble strips in reducing travel speeds approaching highway work zones. The evaluation consisted of measuring travel speeds of motorists as they approached work zone areas with and without temporary rumble strips, and comparing changes in average speed, speed distribution, and the proportion of speeding vehicles. The results of this evaluation indicated that the use of temporary rumble strips in advance of construction work zones reduced vehicular speeds once motorists encountered the temporary rumble strips. Therefore, the use of temporary rumble strips prior to a construction work zone may be a practical countermeasure to reduce vehicular speeds through the work zone.

Shoulder and centerline rumble strips have become a predominantly used safety measure along American highways in almost all states and in Canadian provinces. Milled shoulder rumble strips are indentations along the shoulder of a highway to warn drivers who may start drifting off the road through an audible and tactile alert. Centerline rumble strips are similar, but are placed between lanes, usually two lane, two way highways, to warn drivers who may start drifting into oncoming traffic. Researchers at Kansas State University (KSU) have conducted research on a new design for highway rumble strips. A new football shaped rumble strip was created by an independent firm in Kansas. Test strips were installed along a Kansas highway, and the KSU Rumble Strip Research Team conducted several tests to evaluate the new football shaped rumble strip versus the rectangular rumble strip. The comparison consisted of water and debris collection, interior sound and vibration production, the opinions of bicyclists, and the opinions of residents in areas where rumble strips are installed. Based on the literature review, the limited tests performed (Water and Debris Removal, Noise, and Vibration), the surveys conducted (Bicyclists on K-96 and residents along US 40), and similarity in cost of the football shaped rumble strips to the rectangular rumble strips, it can be concluded that no significant difference was found between the two types. The KSU Rumble Strip Research Team concludes that the football shaped rumble strips can be considered an effective alternative to the rectangular rumble strips.

This research attempted to measure the safety benefits achieved from rumble strips along roadways in Connecticut. Safety benefits are considered a reduction in single-vehicle, fixed object, run-off-the-road accidents. This study used the Comparison Group methodology to predict rumble strip accidents, without reference to causal factors such as driver behavior, accident reporting, and traffic counts. The study concludes with guidance to researchers about causal factors such as traffic that can be incorporated into future rumble strip studies.

An evaluation of shoulder rumble strip's effectiveness in reducing off-road and rollover crashes on Montana's highway system utilized 10 years of crash data on 393 miles of Interstate Highways and 213 miles of National Highway System (NHS) and Primary Highways. Statistical analysis of crash data involved rumble strip segments and control segments without rumble strips for 3 year periods before and after implementation of shoulder rumble strips. Descriptive statistics were developed from global data sets and comparative statistics on equivalent segments produced a finding of significant crash reductions on Interstate Highways, while the effect of shoulder rumble strips on NHS and Primary Highways was uncertain due to an inadequate sample size. Analysis of contingency tables indicate that the reduction in Interstate off-road crash rates attributable to shoulder rumble strips was 14.0% with a corresponding reduction of 23.5% in severity rates. The benefit/cost ratio for construction of shoulder rumble strips on Interstate highways was 19.5. A shoulder rumble strip driver survey involving questions related to knowledge of rumble strips, frequency of encounters, reaction to exposure, and general opinions on their use was incorporated as part of the study. The survey indicated that 95% of the driving public was familiar with rumble strips and their use with the majority of drivers encountering rumble strips on every highway trip. The overwhelming majority of motorists liked the benefits that shoulder rumble strips provide.

Discusses Massachusetts' experience with rumble strips in the centerline of undivided highways.

Discusses a Maryland Department of Transportation (DOT) project involving installation of a "rumble strip" down the middle of an undivided state highway.