A feature article in the July 2019 edition of Roads & Bridges shares the importance of applied research at the local level. Iterative research, the research cycle, and integrated communication strategies are all essential components to understanding the needs of your customers, implementation barriers, and developing clear outreach tools.
As a part of Minnesota’s County Road Safety Plan (CRSP), MnDOT identified road departure crashes as a high priority. MnDOT staff took the first step of the implementation cycle by asking the question: How do we reduce road departure crashes?
After review of the National Cooperative Highway Research Program (NCHRP) 500 series reports, a short list of strategies was identified, and a single strategy was recognized to implement—shoulder rumble strips. Rumble strips were installed on hundreds of miles of local roads, at locations where local agencies were willing to install a new type of safety strategy. Although they performed well in terms of safety—warning drivers that they were near the edge of the road, MnDOT did not anticipate noise complaints from residents along the county roadway and challenges for bicyclists.
Through in-field investigation, MnDOT staff determined that a rumble design with a 6-inch pavement marking with 4-inch of grooving this is painted and an additional 2-inch of grooving outside the painted edge line may be the solution. The information was communicated via email blasts and newsletters to state and local agencies, universities, and consultants. However, this solution did not totally satisfy noise complaints.
After a thorough investigation on existing national research and best practices by other states and countries, a rumble that was cut into the pavement to represent a sinusoidal curve was determined successful and numbers don’t lie! Since the widespread deployment of targeted safety strategies on county roads in 2012, 393 projects of low-cost safety strategies improvements, many of which included rumble strips, have been installed on the county road network and have resulted in a 14% reduction in the fatality rate. To reach this reduction, Minnesota safety stakeholders had to take risks and be willing to test strategies with little formal research to prove effectiveness. Further, they had to communicate the strategies to the public, so that they understood the reasons behind the change.