The Iowa Department of Transportation intends to maintain and upgrade nearly 9,000 miles of highways and 4,100 bridges with a proposed investment of $3.5bn under a five-year plan.

With this investment, it aims to bolster safety, maintenance as well as modernise the current road system.

The department plans to invest $1.2bn on bridges owned by the state.

"Iowa’s economy is dependent on a robust and diverse transportation system to move products to a global marketplace."

The recent years have seen the count of structurally deficient bridges on highways being cut down to 81 in 2015 from 256 in 2006.

The Gazette quoted DOT as stating: "Transportation powers the creation of wealth in our nation and state, unleashing opportunity for economic activity.

"Iowa’s economy is dependent on a robust and diverse transportation system to move products to a global marketplace.

"Iowa’s transportation system has long provided our state’s businesses a competitive advantage and that remains true today in the global economy."

As part of the five-year plan, the department will undertake major reconstruction work on Interstate Highway 29 in Sioux City, on the interstate system in Council Bluffs.

The plan also includes completion of the expansion of US Highway 20, which will enable the completion of a four-lane expressway between Dubuque and Sioux City, reported the publication.

The Iowa Transportation Commission, which is the DOT’s policy making wing, is slated to give its approval to the five-year plan in June.