Oversized loads pose special challenges for work zones on Iowa highways

WindbladeIn Iowa, big things are moving on our highways. Whether you see a flatbed loaded with a massive piece of farm equipment or a specially designed truck hauling a huge wind blade, oversize and/or overweight loads are a common sight on Iowa roads. Sometimes traveling around these types of loads can cause frustration or pose challenges but a lot of planning goes into making sure those loads are traveling safely down our roadways and around other traffic.

Typically, large loads safely travel around our state without many issues, delivering the goods that fill store shelves, supplying manufacturing plants, and moving other freight that make our lives better. During construction season, trips get a little more difficult to plan with work zone-related road closures and lane restrictions popping up daily.

To make sure larger-than-standard loads move in the safest manner possible, trucking companies are required to apply for special permits to move oversize or overweight cargo. When applying for a permit for a specific load, the shipping company provides all the size and weight information, along with the starting point and destination of the shipment. The Iowa Department of Transportation’s automated system uses data from and other data sources to check route options against the information provided by the shipper to find the best route. Once the safest route is determined, the permit is issued. In 2021, 109,424 of these oversize or overweight permits were issued.


Alex Jansen, the Iowa DOT’s motor carrier program manager, said, “There are a number of state and federal regulations related to the movement of oversized loads. We have a great relationship with our trucking industry partners and work with them to make sure all those requirements are met and to find the best route possible to get their goods where they need to go. That doesn’t mean there’s no room for improvement, we can always get better. One area we’re working on is routing of oversize loads to avoid issues in work zones.”

Clayton Burke, a safety engineer in the Construction and Materials Bureau is the Iowa DOT’s work zone coordinator. He said, “The work zone restriction information we provide to our own staff, the public, and motor carriers is critical to the safety of not only the drivers on the road but of our workers in the construction zone. That information is entered into a database and can be found at in the ‘construction’ layer.”

511 restrictions map
Work zones pop up all over Iowa this time of year. The “Restrictions for commercial vehicle” layer gives motor carriers the information they need to plan a safe route.


The information you can easily find on is the same data that is fed into the permitting system, allowing that automated system to find an unrestricted route. But the route is only going to be viable if the information in the system is accurate and complete.

“That’s one area we’re working to refine,” said Burke. “We’re talking with our own motor carrier staff to define a ‘restriction’ as it relates to larger trucks. An example would be if we have a work zone with a narrow lane that has concrete barriers, that’s definitely restrictive for a wide load. If a similar width restriction is in place and the work zone is separated by plastic cones or channelizers, that needs to be listed as a restriction, as well. Although the load could probably pass through the work area without damaging the road or the load, this type of issue could potentially create a significant safety hazard for workers.”

OSOW in a work zone
Motor carriers are required to obey all restrictions in a work zone. When that doesn’t happen, it can put workers at risk and cause you to be delayed waiting for the truck to be moved.

Although the routes for loads are automatically checked prior to a permit being issued, many carriers who regularly move large loads are granted annual permits. In 2021, the Iowa DOT issued  15,1576 annual permits.

These types of permits allow the carrier to move loads as needed, but the carrier is mandated to follow all state and federal restrictions and required to check for roadway restrictions prior to the load taking to the road.

Jansen said, “The carrier is required to check for restrictions. That’s why it is critical that the information on this site be accurate, easy to access, and easy to follow.”

511 width restriction

This construction season as you’re traveling around the state, please be cautious of all the traffic sharing the road with you.  A little patience will go along way to make sure everyone gets where they need to go safely.




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