Traffic & Safety

Reduced-conflict intersections

Live Tabs

Poplar Ave. & U.S. 20

Poplar Ave. & U.S. 20

What are they?

Reduced-conflict intersections reduce the number of points where vehicles can inadvertently come into contact with other vehicles, often called conflict points, by 50 percent. A typical four-lane divided highway intersection has 42 possible vehicle conflict points while reduced-conflict intersections have as few as 24.

Reduced-conflict intersections improves mobility and greatly reduce the number of severe crashes common when drivers must cross over busy highways to reach another road. They decrease fatalities and injuries caused by broadside crashes on four-lane divided highways.

Typical Four-lane Divided Highways


Possible vehicle conflict points

Reduced Conflict Intersection


Possible vehicle conflict points

Why do they work?

Couple driving car

With a reduced-conflict intersection, when you are turning from a side street to a four-lane highway, you only have to be concerned with one direction of traffic on the highway at a time. You don’t need to wait for a gap in both directions to cross a major road.

Traditional four-lane divided highway intersections have an elevated risk of severe right-angle crashes (commonly called “T-bone” crashes) when you are crossing all four lanes of traffic. The driver from the side street needs to keep track of traffic in both directions at one time to cross the four-lane divided highway or make a left turn. In a reduced-conflict intersection, when vehicles do come into contact with each other, crashes have been shown to significantly reduce the severity of crashes compared to traditional intersections.

Click icon at the bottom right of the image to enlarge

How do they work?

In a reduced-conflict intersection, drivers on the side road wanting to turn left or cross the four-lane highway will:

  1. Turn right onto the highway
  2. Merge into the left lane
  3. Make a U-turn at a designated median opening.

The way the pavement is configured, you cannot make a left turn onto the four-lane highway or cross both directions of traffic. This reduces potential conflict points and increases safety.

While this might sound like it will take you longer to turn, generally, the delay caused by a traffic signal or just waiting for traffic to clear at a two-way stopped-controlled intersection is greater than the delay caused by the reduced-conflict intersection.


  • Improved safety — Studies show a 70 percent reduction in fatalities and a 42 percent reduction in injury crashes where a reduced-conflict intersection is used.
  • Faster to build — reduced-conflict intersections can be designed and built in approximately one year. Interchanges typically take 3-5 years and are not practical at all locations.
  • Lower cost — reduced-conflict intersections are often less expensive than constructing and maintaining an intersection with a traffic signal and are a fraction of the cost of building an interchange.


Login  |  ©  Iowa Department of Transportation.  All rights reserved.