Policy Considerations and Evaluation of the Safety Effectiveness of Rumble Strips in Wyoming: Accommodation of All Road Users

Rumble strips/stripes are used by many states as a relatively low cost proven safety countermeasure to reduce or prevent lane departure crashes by providing a vibrotactile and audible warning to inattentive motorists. Although the advantages of rumble strips are generally found to outweigh the disadvantages, several issues and concerns have been identified regarding the implementation of rumble strips. The main goal of this study is to develop an effective policy of shoulder and centerline rumble strips/stripes in the State of Wyoming to enhance motor vehicle safety while accommodating all road users to the highest practical extent. Surveys were conducted to assess road users' concerns about rumble strips. Moreover, several issues regarding the use of rumble strips/stripes including: construction, maintenance, and noise are discussed. With the help of WYDOT, information regarding the state of practice of rumble strips/stripes in the U.S. was collected. Information was obtained through a review of the literature, online survey, and email communication with States DOTs. Thirty states responded to the online survey. Only four agencies have fully adhered to the NCHRP guidelines; Idaho, Mississippi, Nevada, and New Mexico. Fifteen agencies indicated that they are using the guidelines provided by NCHRP with some modifications to suit the needs of their region. Seven agencies are using their own guidelines; Alabama, Kentucky, Massachusetts, New Hampshire, North Dakota, Texas, and Wyoming. Among the agencies which took the survey, only Oklahoma responded that they do not have a written policy for rumble strips.;Based on the DOTs guidelines identified recently from the literature and survey responses, thirty state agencies have already made provisions to accommodate bicyclists. Only three agencies responded that they do not have any provisions for bicyclists while the remaining eighteen state agencies indicated that they do not have adequate information to address this issue.;The rest of the survey results showed that many DOTs are still updating their rumble strip policies. DOTs which had already been using their own guidelines are now moving forward to accommodate the non-conventional vehicles and nearby residents. About 72 percent of the states are following the NCHRP Report 641 guideline, either strictly or with some modifications. Application criteria and maintenance practices vary by state. Shoulder rumble strips are more widely used than centerline rumble strips or shoulder rumble stripes. Rumble strips are installed mostly on rural roadways since they possess fewer constraints on installation criteria. All of the 30 states which responded to the survey are using SRS and among them 27 states are using CLRS. The use of the combination of SRS and CLRS is not adopted by all the states, only 55 percent of the states are using both types in combination. Although the NCHRP 641 issued guidance on how state agencies can balance the increase in rumble strips implementation while accommodating all roadway users, 16 percent of state DOTs have indicated that their policies do not have any provisions for bicyclists when installing rumble strips, whereas, 42 percent of the DOTs do not consider noise when installing rumble strips. Most of the DOTs commented that they try to avoid installing rumble strips in urban areas to prevent noise. From the survey responses, information gathered in earlier surveys, and from synthesis documents; it was found that 36 states made provisions to accommodate bicyclists; while only 3 states; Idaho, Maine, and Florida attempted to accommodate motorcyclists. Maine DOT provides skip pattern on centerline rumble strips in rumble strips to facilitate motorcycle lane changes. Idaho DOT uses centerline rumble strips only in no-passing zones. The governing criteria ranked by DOTs when a roadway is considered for installing rumble strips are in the following order; area type (urban vs. rural), guardrail, pavement type, pavement thickness, bicycle traffic, motorcyclists, noise, nearby residents.;An Expert System has been developed to provide an interactive easy way to navigate through rumble strips/stripes practices and guidelines in the U.S. It is recommended that the information compiled in the 'Expert System' should be fully utilized when adopting a new policy. It is also recommended that other DOTs implement or upgrade their rumble strips policies may utilize recent information presented in this study.;Nine rural two-lane segments of 121.6 miles were identified for safety effectiveness analysis and to calibrate Crash Modification Factors (CMF) for rumble strips in Wyoming. Three years of crash and traffic data in the before and after were used to conduct a Naive before-after analysis. The results showed significant effect of shoulder rumble strips on reducing target crashes and total crashes. Total crashes reduced by 40%. Additionally, Fatal and Injury (F+I) crashes, and Single Vehicle Run-Off-Road (SVROR) crashes reduced by 44% and 39%, respectively. (Abstract shortened by UMI.).