Rural intersections account for 30% of crashes in rural areas and 6% of all fatal crashes, representing a significant but poorly understood safety problem.
Transverse rumble strips are one low-cost measure that some states have deployed to reduce rural intersection crashes.
More common to Minnesotans are traditional rumble strips, which are pavement indentations usually applied along the shoulders or centerline that cause noise and vibration when a vehicle drives over them. They are widely used on Minnesota roads and have been successful in alerting motorists that stray from the travel lane, reducing Minnesota crashes (especially head-on collisions).
Transverse rumble strips, however, are located across the lane (or exclusively in the main wheel path), with the purpose of signalizing an upcoming intersection with a stop sign along a rural roadway, so that drivers don’t unintentionally run the stop sign, especially during times of low visibility.
The effectiveness of transverse rumble strips has shown mixed results. However, this may be partly due to collisions caused by driver misperception of traffic gaps, rather than failure to stop for stop signs.
“There is a lack of consistency in the placement and pattern for transverse rumble strips among U.S. transportation agencies,” said Shauna Hallmark, director of the Institute for Transportation at the Iowa State University.
In a new research project, funded by the Local Road Research Board, Hallmark and other researchers from Iowa State University will assess the effectiveness of transverse rumble strips, as well as the best design, for possibly more widespread application in Minnesota.
Researchers will test three to five different transverse rumble strip designs—varying placement, the number of panels, and patterns. They plan to collect video data before installation, one month after, and six months after to assess changes in driver behavior.
“Transverse rumble strips are one tool in the rural safety toolbox. We want to learn when and how to best use this tool—so we can get it back in the hands of local practitioners,” said Victor Lund, St. Louis County Traffic Engineer, who is leading an advisory panel of county and state traffic engineers that includes Scott Thompson, District 7, and Marc Briese, State Aid.
Lund, who is actively involved in MnDOT’s rural safety research and with four other research projects, happened to have studied under Hallmark during graduate school and is excited to collaborate with her on this study.
Hallmark has over twenty years of transportation research experience on effective countermeasures for reducing crashes on our roadways.
Although the majority of crashes at rural intersections are due to driver misperception of traffic gaps, transverse rumble strips could still play an important role in rural road safety and getting Minnesota Toward Zero Deaths.
In addition to evaluating their effectiveness, Hallmark’s team will look for a design that is palatable to Minnesotans.
“People have a love-hate relationship with rumble strips. Drivers love the protection they offer, but nearby homeowners hate the noise. We want to identify the most effective, yet also quietest design possible,” she said.
To request project updates or learn more, visit MnDOT’s Office of Research & Innovation.