Bridges in Iowa
There are more than 24,000 bridges and structures in Iowa. The Iowa DOT is responsible for 4,092 that are part of the state’s Primary Highway System, which includes the interstate, U.S. and "Iowa" state highways.

To provide access to information about Iowa's Primary Highway System bridges, the Iowa DOT has developed a Web-based application that allows visitors to pinpoint a bridge in their area using Google Earth™ software and retrieve data about that bridge from the Iowa DOT's bridge inventory database. Information available includes the year the bridge was built, year the bridge was reconstructed (if it has undergone major work), average annual daily traffic count (AADT), highway it carries, feature crossed (waterway, highway, railroad, drainage ditch, etc.), sufficiency rating, and whether the bridge is classified as structurally deficient and/or functionally obsolete.

The phrases "structurally deficient," "functionally obsolete" and "sufficiency rating" are federal terms used to identify bridges eligible for funding assistance under the federal Highway Bridge Replacement and Rehabilitation Program. Structurally deficient refers to bridges needing significant maintenance attention, rehabilitation or replacement. Functionally obsolete refers to bridges with deck geometry (e.g., lane width, shoulder widths), load carrying capacity, vertical clearance or approach roadway alignment that no longer meet the criteria for the system of which the bridge is a part.

The sufficiency rating formula is a method of evaluating factors that indicate a bridge's sufficiency to remain in service. The result of the formula is a percentage in which 100 percent represents and entirely sufficient bridge and zero percent an entirely insufficient or deficient bridge. Many factors are included in the ratings. The sufficiency rating doesn't necessarily indicate a bridge's ability to carry traffic loads. It helps determine which bridges may need repair or replacement. Any bridge in Iowa found to be unsafe is removed from service until it can be returned to a safe state of operation or replaced.

You will need Google Earth installed on your computer to access this information.
  • If you don't already have Google Earth, download it for free (14.3 Mb) and install it.
  • Click on Primary Structures (kmz 228 KB). Choose save to save the file to your computer's hard drive. Once the file has been saved to your computer, a dialog box will appear. Then click open.
  • On the left hand side of the screen you will see a menu called Places. This shows a list of all bridges on Iowa's primary highway system. Click once on the county to see information about the bridge, click twice on the county to zoom into the location of the bridge. The bridge locations indicated as a green dot within the map can also be clicked to see the information.
PDF Document  View a list of Iowa's primary highway bridges.
U.S. bridge information addresses frequently asked questions regarding bridges in the federally financed U.S. transportation system, including numbers of bridges, condition of the bridge inventory and work done in recent years to improve and invest in that inventory.