Of Iowa's more than 24,000 bridges, 21% are classified as structurally deficient, according to a report by the American Road and Transportation Builders Association. Iowa has 5,000, nationwide there are 55,000 structurally deficient bridges.
"A structurally deficient bridge doesn't mean that it is not safe or it can't carry traffic, what it means is there are members of the bridge that are in poor condition and can't carry a full load so it is weight rated, for instance the Gordon Drive Viaduct carries a weight restriction on it," said Dakin Schultz, Iowa DOT.
So that is why many times you will see signs posted regarding load limits..
On Correctionville Road, just outside of Sioux City, is a bridge that is both structurally deficient and functionally obsolete. The bridge was built back in the 1930's, and is incapable of handling heavy truck loads and traffic.
These bridges are too narrow and when farm equipment or trucks pass, they usually cross into the center line.
"Our new bridges are at least 30 feet wide, this one is 22 which is very narrow for two vehicles to meet at the same time, it also doesn't have the safety features we put on bridges now where we have rails that tend to redirect an accident rather than pocketing a colliding vehicle," said Mark Nahra, Woodbury County Engineer.
The average life span of a bridge is about 42 years, a lot of Iowa bridges are half a century old.
Detailed inspections are done every 2 years, and structurally deficient bridges get inspected every year.
"We look at that bridge from top to to stream bed, we check the deck, we check the rail, we check the superstructure rather it is concrete, steel or wood, we look at any visible portions of that bridge," continued Nahra
Woodbury County had the most bridges in Iowa classified as structurally deficient.
But to put things in perspective, Woodbury County also have the largest amount of bridges, so it is reasonable that they would have the highest amount of bridges in need of repair.
Although Iowa has 5,000 structurally deficient bridges, Nebraska has almost 2,500. South Dakota has just over 1,000.