National Bridge Inventory: Iowa
- Of the 23,982 bridges in the state, 4,571, or 19.1 percent, are classified as structurally deficient. This means one of the key elements is in poor or worse condition.
- This is down from 4,671 bridges classified as structurally deficient in 2016.
- The deck area of structurally deficient bridges accounts for 10.0 percent of total deck area on all structures.
- 6 of the structurally deficient bridges are on the Interstate Highway System. A total of 99.5 percent of the structurally deficient bridges are not on the National Highway System, which includes the Interstate and other key roads linking major airports, ports, rail and truck terminals.
- 5,416 bridges are posted for load, which may restrict the size and weight of vehicles crossing the structure.
- The state has identified needed repairs on 15,308 bridges at an estimated cost of $3.1 billion.
- This compares to 15,178 bridges that needed work in 2016.
|County||Year Built||Daily Crossings||Type of Bridge||Location|
|Scott||1940||30,400||Urban other principal arterial||Centennial Bridge|
|Scott||1970||25,100||Urban Interstate||I-280 over Mississippi River & Road|
|Scott||1963||20,000||Urban minor arterial||N Division St over Duck Creek|
|Polk||1936||18,600||Urban minor arterial||2nd Ave over Birdland Dr|
|Polk||1967||17,600||Urban minor arterial||Sw 9th St over Cherry, RR, Mlk Pkwy|
|Scott||1900||16,700||Urban minor arterial||Eastern Ave over Duck Creek|
|Woodbury||1962||14,550||Urban Interstate||I-29 over Channel Floyd River|
|Johnson||1972||14,500||Urban minor arterial||Gilbert St over Ralston Creek|
|Woodbury||2017||13,450||Urban Interstate||I 29 NB over Perry Creek Conduit|
|Poweshiek||1963||13,250||Rural Interstate||I 80 WB over Iowa 21|
|Poweshiek||1962||12,900||Urban Interstate||WB I 80 over Iowa 146|
|Poweshiek||1962||12,900||Urban Interstate||EB I 80 over Iowa 146|
|Marshall||1951||11,100||Urban minor arterial||So Center St over RR and Madison St|
|Polk||1958||10,800||Urban minor arterial||Se 30th St over UP RR|
|Johnson||1915||10,650||Urban other principal arterial||Ia 1 NB over Iowa River|
|Webster||1968||10,300||Urban minor arterial||1St Ave S over 21St St & RR|
|Linn||1938||10,050||Urban other principal arterial||8th Ave over Cedar River|
|Woodbury||1962||9,900||Urban minor arterial||Dace Ave over Floyd River|
|Scott||1895||9,900||Urban minor arterial||Fort Rd & RR over Mississippi River|
|Black Hawk||1950||9,800||Urban minor arterial||E Ridgeway Ave over Dry Run Creek|
|Woodbury||1962||9,500||Urban minor arterial||6th St over Floyd River|
|Webster||1955||9,300||Urban other principal arterial||5th Ave over drainage Ditch|
|Plymouth||1948||8,300||Rural arterial||SB US 75 over Stream|
|Woodbury||1976||8,000||Urban minor arterial||Military Rd over Big Sioux River|
|Black Hawk||1953||7,400||Urban minor arterial||E 11th St over Cedar River|
|Type of Bridge||Number of Bridges||Area of All Bridges
|Daily Crossings on All Bridges||Number of Structurally Deficient Bridges||Area of Structurally Deficient Bridges
|Daily Crossings on Structurally Deficient Bridges|
|Rural minor arterial||1,076||610,204||2,051,540||18||13,164||32,530|
|Rural major collector||3,447||1,266,262||2,591,408||590||189,383||397,590|
|Rural minor collector||3,882||995,049||552,265||724||137,037||85,295|
|Rural local road||11,600||1,823,063||621,457||3,066||337,776||129,402|
|Urban other principal arterial||628||1,105,636||5,641,410||4||23,327||60,400|
|Urban minor arterial||544||615,387||3,502,697||45||69,960||296,635|
|Urban local road||503||179,727||459,216||78||42,292||42,501|
|Type of Work||Number of Bridges||Cost to Repair
|Daily Crossings||Area of Bridges
|Widening & rehabilitation||67||$28||119,429||36,553|
|Other structural work||6,723||$1,326||2,778,033||1,740,695|
About the data:
Data is from the Federal Highway Administration (FHWA) National Bridge Inventory (NBI), downloaded on March 11, 2021. Note that specific conditions on bridges may have changed as a result of recent work or updated inspections. Cost estimates were downloaded by ARTBA on March 11, 2021.
Effective January 1, 2018, FHWA changed the definition of structurally deficient as part of the final rule on highway and bridge performance measures, published May 20, 2017 pursuant to the 2012 federal aid highway bill Moving Ahead for Progress in the 21st Century Act (MAP-21). Two measures that were previously used to classify bridges as structurally deficient are no longer used. This includes bridges where the overall structural evaluation was rated in poor or worse condition, or where the adequacy of waterway openings was insufficient.
The new definition limits the classification to bridges where one of the key structural elements—the deck, superstructure, substructure or culverts, are rated in poor or worse condition. During inspection, the conditions of a variety of bridge elements are rated on a scale of 0 (failed condition) to 9 (excellent condition). A rating of 4 is considered “poor” condition.
Cost estimates have been derived by ARTBA, based on 2019 average bridge replacement costs for structures on and off the National Highway System, published by FHWA. Bridge rehabilitation costs are estimated to be 68 percent of replacement costs. A bridge is considered to need repair if the structure has identified repairs as part of the NBI, a repair cost estimate is supplied by the bridge owner or the bridge is classified as structurally deficient. Please note that for a few states, the number of bridges needing to be repaired can vary significantly from year to year, and reflects the data entered by the state.
Bridges are classified by FHWA into types based on the functional classification of the roadway on the bridge. Interstates comprise routes officially designated by the Secretary of Transportation. Other principal arterials serve major centers of urban areas or provide mobility through rural areas. Freeways and expressways have directional lanes generally separated by a physical barrier, and access/egress points generally limited to on- and off-ramps. Minor arterials serve smaller areas and are used for trips of moderate length. Collectors funnel traffic from local roads to the arterial network; major collectors have higher speed limits and traffic volumes and are longer in length and spaced at greater intervals, while minor collectors are shorter and provide service to smaller communities. Local roads do not carry through traffic and are intended for short distance travel.
Compared to 3 in 2019
in the nation in % of structurally deficient bridges
Compared to 1 in 2019
in the nation in # of structurally deficient bridges
Compared to 7 in 2019
in the nation in % of structurally deficient bridge deck area