New Fort Dodge intersection developed to reduce number of crashes and serious injuries

IMG_7869If you’re a parent of more than one child, you know a thing or two about how to reduce conflict. Some sage advice includes separating the conflicting items (in this instance, children) to give them time to think about what to do next, potentially reducing the risk of injury.

It’s really not so different with drivers approaching an at-grade intersection on a four-lane highway. The more you can separate the drivers and give them time to think about what’s next, the fewer conflicts or crashes will happen and the severity of the conflicts that do happen is reduced.

That’s exactly what is going on right now on U.S. 20 at Poplar Avenue near Fort Dodge. A new “reduced-conflict” intersection was opened recently with the goal of seeing fewer crashes and injuries at an intersection that may be getting much busier soon with the opening of a travel plaza.

Here’s how to cross U.S. 20 from northbound Poplar Avenue. 

MM1352_RCI US20 Ft Dodge_north

Drive through the interchange from southbound Poplar Avenue.

MM1352_RCI US20 Ft Dodge_south

What is a “reduced-conflict” intersection?

Reduced-conflict intersections are designed to reduce the number of conflict points where vehicles can crash into each other. Our neighboring states of Minnesota, Wisconsin, and Missouri have multiple intersections like these that have proven to be successful in decreasing fatalities and injuries caused by broadside crashes on four-lane divided highways.

Why do they work?

The updated intersection improves mobility and increases safety by reducing the number of points where vehicles can inadvertently come into contact with other vehicles by 50 percent.

Willy Sorenson, an Iowa DOT traffic safety engineer, is all about the numbers when it comes to reducing crashes. He said, “A typical four-lane divided highway intersection has 42 possible vehicle conflict points. Reduced-conflict intersections accomplish just what the name would imply, reducing conflict points to as few as 24. Simply put, this type of intersection makes it more difficult for drivers to crash and when they do crash, those crashes will be less severe.”

RCI comparison graphic
The red dots on this diagram represent the potential for the most severe types of crashes, the blue and yellow dots are typically less severe. Reduced conflict intersections improve safety because they have significantly fewer potential crash or conflict points than conventional intersections.

How do they work?

Think back to the parenting scenario. Like separating your conflicting children and giving them time to think, this type of intersection separates vehicles and gives drivers time to think about one driving activity at a time. It works like this: 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 the major road.

IMG_7862In a reduced-conflict intersection, drivers on the side road wanting to turn left or cross the four-lane highway will turn right onto the highway, merge into the left lane and then make a U-turn at a designated median opening. The way the pavement is set up, you cannot make a left turn onto the four-lane highway or cross both directions of traffic. 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.

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, the severity of crashes is much less compared to traditional intersections.

What are the benefits of a 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.

For more information on reduced conflict intersections, go to

Hi John - I responded to this by email but wanted to close the loop on your comment, too. Yes, this area is being looked at for possible improvement.


Has there been any discussions about the intersection that I shared in my note on 09/20/2022 above. This intersection could use some type of upgrade to help improve safety for all drivers that drive through that intersection every day. It would great to know if there has been some discussion about making this intersection safe for everyone. Thanks for your time and have a great day.

This is what Boone needs at airport road and hwy 30

This reduced-conflict intersection would be nice for the intersection of U Ave. and U.S. 30 just southwest where United Community School District is located. This intersection is about 2 or 3 miles West of Ames on U.S. 30. Over the years I have seen an increase traffic at this intersection as I drive to work. It does not look safe for anyone going through this intersection. I am always taking my time going by that intersection just to be ready if someone makes a mistake. I don't know what are the requirement as far as putting an reduced-conflict intersection at the intersection and it is probably a long shot. Just like building a bridge to the east of that intersection is a long shot also. But there has to be something that can be done to help make that intersection safer. Thanks for your time and have a great day.

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