Lakeside Interceptor | Duluth, MN

Rural Intersection Collision Warning Systems

Nichole Sungren, PE | with 0 Comments

Rural Intersection Collision Warning Systems

I recently attended the 2015 Traffic and Safety Forum, co-sponsored by the Iowa DOT and ICITE (Iowa Central Chapter of the Institute of Transportation Engineers) that was held in Ames, Iowa.  The topic of Rural Intersection Collision Warning Systems (ICWSs) generated a lot of interest at the Forum.  With traffic fatalities trending upward in 2015, the focus on increased intersection safety is justified.

What are ICWSs?
ICWSs are systems of signage and flashing lights that warn motorists of approaching vehicles along cross streets (minor roads) and high-speed roadways (major roads). The warning systems can be designed for the approach from major roads, minor roads, or a combination of both major and minor roads.

Currently there are six ICWS installations in Iowa. The Minnesota DOT has 50+ installations throughout Minnesota, so the Iowa DOT looked to them for guidance when implementing their own installations. 

Preventing Fatalities
The purpose of ICWSs is to prevent fatalities, not necessarily to prevent all crashes. The types of crashes typical at these major and minor road intersections are side or “T-bone” crashes.   When ICWSs are installed with warning for mainline vehicles included, these drivers are more likely to reduce speeds.  What could have been a fatal crash is often reduced to a minor injury or property damage only crash.  Data has shown that fatal and major injury crashes were reduced 50-100% at the locations with mainline warning systems.
Cameras are mounted on all ICWSs in Iowa to record actual crash data for educational purposes. During the 2015 Traffic and Safety Forum in Ames, we were able to view crash footage from one of Iowa’s installations. The passenger was able to exit the vehicle post-crash because the driver reacted to the sign, reduced speed and swerved in time to avoid what would otherwise have likely been a fatal crash.
Which intersections most benefit from ICWS?
Traffic engineers consider several things when evaluating intersections for the potential installation of ICWSs. Communities could benefit from ICWSs when one or more of the following are present.
  • close proximity to a railroad crossing
  • a skewed intersection
  • a horizontal curve within a ¼ mile of the intersection
  • commercial development within one quadrant of the intersection
  • high crash histories 
  • high traffic volumes
  • more than 5 miles since previous stop sign (side street direction)
After completing the currently scheduled ICWS installations, the Iowa DOT is reviewing all intersections within its primary system as potential ICWS candidates. Be on the lookout for ICWS the next time you travel through Iowa.
MSA’s traffic engineering experience spans a wide range of projects. Whether it’s more traditional topics like development impacts or analysis, or the ever changing world of roundabout design, we’ve got you covered. Contact MSA’s Nichole Sungren for more information.

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