Iowa DOT News Release

New mainline interstate closure gates to be tested this winter

Posted on: October 29, 2010

AMES, Iowa – Oct. 29, 2010 – The Iowa Department of Transportation (DOT) is further implementing a pilot project to test use of automated mainline interstate closure gates at key interstate interchanges. The first set of gates was installed in January at the southbound Interstate 35/U.S. 18 interchange near Mason City.  Additional sets are presently being installed at the northbound I-35/U.S. 30 interchange in Ames and northbound I-29/U.S. 30 interchange in Missouri Valley. 

The new mainline interstate gates, as well as existing on-ramp gates, will be used when the roadways are blocked or must be closed due to inclement weather (e.g., blizzard, ice storm or flood), crash, hazardous material spill or other emergency. 

Presently, the Iowa DOT uses swing-type, farm-style fence gates, hinged to posts, on the on-ramps at several interstate interchanges. Deployment of these gates requires law enforcement or highway maintenance personnel to physically move the free end of the gate out across the ramp during dangerous road and weather situations.

Prior to this pilot project, no gates were in place on the mainline to restrict existing traffic from continuing to travel into the blocked/closed interstate section. Absent a gate, the Iowa DOT was required to park snowplows across the travel lanes during a blizzard to stop traffic. This practice has had limited success, and is an inefficient use of staff and equipment resources during a time when they are needed most performing snow removal.

The new drop-arm style gates not only close the interstate mainline to traffic, but all facets of the road closure system (i.e., gates, lights and advance warning lights) will be monitored and controlled remotely. Area video cameras will also allow Iowa DOT personnel to monitor site traffic and weather conditions.

During the 2010-11 winter season, the Iowa DOT will be evaluating: the reliability and operational performance of this type of gate system in extreme environmental conditions; frequency of use; traveler response; and efficiencies that may be gained in the department’s operations.

Analysis of these three pilot test areas could help the department determine desired gate improvements for other parts of the state in those locations where conditions allow. Some of those conditions include implementation feasibility, budgetary considerations and the availability of facilities (e.g., motels, restaurants, truck parking areas, etc.) in the near proximity to the mainline gate closure location.   

Another advantage of the automated gates is that they can be easily operated to allow emergency rescue crews, law enforcement, snowplows, and tow trucks to enter or exit the closed section of roadway so they can carry out their operations, and get the road reopened as quickly and as safely as possible.

The mainline gates also provide a more visible and consistent message to the traveling public in comparison to use of other road closure methods, such as orange fencing, cones, barriers and signs that tend to blow away during a blizzard or when drivers move or drive around them.  

The cost of the gates is approximately $15,000 each. In addition to the gates, caution lights and dynamic message signs will be used to alert drivers when the interstates are closed. 


Contact: Annette Dunn at 515-239-1355 or

(Editor’s note: images of the new gates can be found at


Iowa highway in the evening