Strategic Highway Safety Plan outlines strategies to reduce crashes on Iowa roadways

SHSP coverWhen you leave your home, get into your car, and set a course for a certain destination, you expect to have a safe trip on reliable roads and bridges. That expectation only happens with a lot of behind-the-scenes planning from a network of professionals who use a variety of tools.

One of the tools traffic safety professionals use is a Strategic Highway Safety Plan. According to the U.S. Department of Transportation, an SHSP is a “statewide coordinated safety plan that provides a comprehensive framework for reducing fatalities and serious injuries on all public roads.”

The Iowa DOT has long been a national leader in traffic safety. Our long-term, strategic approach dates back several decades, so the development of a formal plan is second nature to us. Earlier this year, the Iowa DOT and our safety partners released the fourth version of the plan covering 2019-2023.

Overall plan development

The development of Iowa’s SHSP was done in consultation with Iowa’s SHSP implementation team and individuals representing each “E” of safety (education, emergency medical services, enforcement, engineering, and everyone else).

5 Es

Jan Laaser-Webb of our Traffic & Safety Bureau said, “In the process of writing an SHSP, our team reviews crash data, traffic volumes, roadway characteristics, along with human behavior. This information is provided to the multi-disciplinary SHSP implementation team to build the framework of the plan. Our SHSP team meets regularly to discuss common crash types and impactful crash prevention strategies. These efforts are the foundation of our safety plan.”

Although every crash has its unique set of circumstances, the team’s collaboration and review of the data determined eight emphasis areas for Iowa:

  • Lane departures and roadside collisions
  • Speed-related
  • Unprotected persons
  • Young drivers
  • Intersections
  • Impairment involved
  • Older drivers
  • Distracted or inattentive drivers

As part of the planning effort, 40 specific strategies were developed to address the eight priority safety emphasis areas. In addition, the implementation team is to reviews to measure the effectiveness of the strategies within the emphasis areas.

Reveiw process

A closer look into one strategy

As you can see from the list above, lane departure was identified as one of Iowa’s priority safety emphasis areas. From 2013 to 2017, 56 percent of fatal and serious injury crashes happen when a vehicle leaves the roadway and crashes. Five strategies were identified to reduce the number of fatal and serious injury lane departure crashes. One of those was the strategy to place centerline and/or shoulder rumble strips on rural two-lane highways on the primary and local systems and, where necessary, install or widen paved shoulders.

Lane departure strategies

If you’ve driven on an Iowa highway, you may have drifted to one side of the road and heard the rumble under your tires. Shoulder rumble strips have been part of the Iowa DOT’s safety strategy since 1987. However, placing rumble strips in the center of a two-lane road is a newer strategy that is low cost and proven to reduce the likelihood of head-on and run-off-the-road crashes.

Laaser-Webb pointed to a recent Iowa State University study on the effectiveness of rumble strips. She said, “This research shows centerline rumble strips work to reduce these types of crashes. Staff from several Iowa DOT areas including design, construction & materials, maintenance, and our district folks put their heads together to redraft Iowa DOT’s centerline rumble design standard. Incorporating new information and improving the standard, the DOT team agreed to move in a new direction. The decision was made to retrofit centerline rumble strips on approximately 800 miles of rural, two-lane highways around the state that will improve traffic safety.” 

Centerline rumbles
Centerline rumble strips can alert a driver when a vehicle is drifting into the other lane.

As with almost every aspect of the Strategic Highway Safety Plan, data drives the centerline rumble strip placement. Safety engineering staff worked closely with Iowa DOT district engineers to identify sections of roadway where centerline rumble strips would make sense. Laaser-Webb said, “We all worked together to develop one statewide project. We looked at areas that don’t currently have centerline rumble strips and then determined if the pavement conditions were acceptable to place the strips on a project that is under construction this summer.”

As we continue to implement strategies within Iowa’s Strategic Highway Safety Plan to reduce the number of fatalities and serious injuries on Iowa roadways, such as centerline rumble strips, the multi-agency group that developed the plan will continue to study the data and further develop and refine strategies to reduce crashes. But, we know there is no silver bullet that will wipe out traffic crashes. Safety takes a mix of strategies that involve not only education, enforcement engineering, and emergency services, but a commitment from everyone. The responsibility for highway safety ultimately lies in the hands of every driver. All drivers need to commit to being a safer driver by understating how their decisions impact roadway safety and continue to change the culture through awareness and conversations about safe driving behaviors.

Iowa’s Strategic Highway Safety Plan doesn’t stand alone. Here’s how the SHSP fits into the larger scale Iowa DOT planning effort. For more on our planning efforts and how they fit together, go to




Why do center rumble strips when new car electronics scream at you about the same thing?

Interesting information.

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