Evaluation of non-freeway rumble strips - phase II.

Michigan Department of Transportation's (MDOT’s) rumble strip program for two-lane high speed rural highways was initiated in 2008 and continued through 2010. This program included implementation of centerline rumble strips (CLRS) on nearly 5,400 miles of two-lane high speed roads that MDOT maintains. This program presented an opportunity to perform a comprehensive evaluation of safety performance of rumble strips, especially CLRS. A two-phase evaluation study of the program was launched to estimate the driver behavioral and performance improvement in the presence of CLRS on two-lane high speed highways and also perform a system-wide “Before” and “After” study of target traffic crashes. The driver behavior-related study and collection of the three years’ “Before” crash data and analysis was performed in Phase I (OR09084A) and the Phase II study was performed to collect the three years of “After” crash data, a program evaluation study, and benefit-cost analysis. The crash analysis indicated statistically significant reductions in all target crashes including, head-on, sideswipe opposite and run-off-the-road left. The study of crashes and their severity resulted in the reduction in fatal and all categories of injury crashes including a 47% reduction in total target crashes and a 51% reduction in target fatal crashes. An economic analysis of the rumble strip program resulted in a benefit-cost ratio of the program to be in the range of 58:1 to 18:1 based on discount rate assumptions of 2% and 10%, respectively. A road user survey indicated strong agreement among the respondents that CLRS is a beneficial safety improvement program.