National Bridge Inventory: Michigan
- Of the 11,284 bridges in the state, 1,240, or 11.0 percent, are classified as structurally deficient. This means one of the key elements is in poor or worse condition.
- This is up from 1,146 bridges classified as structurally deficient in 2017.
- The deck area of structurally deficient bridges accounts for 7.7 percent of total deck area on all structures.
- 75 of the structurally deficient bridges are on the Interstate Highway System. A total of 82.9 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.
- 1,217 bridges are posted for load, which may restrict the size and weight of vehicles crossing the structure.
- The state has identified needed repairs on 2,684 bridges at an estimated cost of $3.1 billion.
- This compares to 2,586 bridges that needed work in 2017.
|County||Year Built||Daily Crossings||Type of Bridge||Location|
|Oakland||1971||209,200||Urban Interstate||I-696 over I-75 & 4 Ramps|
|Wayne||1967||103,925||Urban Interstate||I-75 over Fort St|
|Wayne||1971||98,506||Urban Interstate||I-94 over Ent to Ford Plant|
|Macomb||1955||82,735||Urban other principal arterial||Mound Rd over Sharkey Drain|
|Wayne||1970||78,863||Urban Interstate||I-96 WB Main Rdwy over M-39 (Southfield Expr)|
|Wayne||1962||74,175||Urban Interstate||I-94 WB over Ecorse Rd|
|Genesee||1957||70,414||Urban Interstate||I-75 over Court St|
|Kalamazoo||1956||69,260||Urban Interstate||I-94 over Portage Road|
|Kalamazoo||1954||67,300||Urban Interstate||I-94 over Norfolk Southern|
|Wayne||1971||65,653||Urban Interstate||I-275 SB over Schoolcraft Rd|
|Wayne||1953||64,700||Urban freeway/expressway||M-10 EB over I-94 Ramp|
|Genesee||1976||63,400||Urban Interstate||I-475 over Gilkey Creek|
|Genesee||1976||63,400||Urban Interstate||I-475 and Ramp B over Chavez Dr|
|Genesee||1976||63,400||Urban Interstate||I-475 over Davison - Broadway Aves|
|Wayne||1953||63,154||Urban freeway/expressway||M-10 WB over I-94 Ramp from M-10|
|Livingston||1960||61,696||Rural arterial||US-23 over M-36|
|Wayne||1969||60,400||Urban other principal arterial||M-102 8 mile Rd over I-75|
|Saginaw||1961||60,342||Urban Interstate||I-75 over CSX RR|
|Wayne||1962||60,077||Urban Interstate||I-94 EB over Beech-Daly Rd|
|Wayne||1955||59,083||Urban Interstate||I-94 EB over I-94 Ramp to M-10|
|Genesee||1971||59,000||Urban Interstate||I-475 over CSX RR & NB Serv Rd(Abn)|
|Jackson||1949||54,000||Urban local road||Elm Rd over I-94|
|Kent||1961||50,972||Urban Interstate||I-296 (US-131) SB over US-131 Br (Leonard)|
|Kent||1962||47,650||Urban Interstate||I-296 WB/US-131 SB over Ann Street|
|Livingston||1962||44,600||Urban Interstate||I-96 EB over Grand River Ave|
|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||626||296,902||3,176,745||56||25,868||209,627|
|Rural major collector||2,101||692,172||4,435,450||253||60,730||535,214|
|Rural minor collector||541||138,774||1,074,602||52||8,411||27,108|
|Rural local road||3,173||563,855||1,546,916||464||52,137||121,784|
|Urban other principal arterial||733||902,080||15,847,580||66||78,970||1,286,681|
|Urban minor arterial||824||753,485||9,615,346||103||78,970||1,121,956|
|Urban local road||591||304,851||2,508,929||66||21,575||188,773|
|Type of Work||Number of Bridges||Cost to Repair
|Daily Crossings||Area of Bridges
|Widening & rehabilitation||75||$87||1,294,624||43,862|
|Other structural work||168||$176||652,927||85,709|
About the data:
Data is from the Federal Highway Administration (FHWA) National Bridge Inventory (NBI), downloaded on January 3, 2022. 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 January 3, 2022.
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 2020 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 11 in 2020
in the nation in % of structurally deficient bridges
Compared to 16 in 2020
in the nation in # of structurally deficient bridges
Compared to 10 in 2020
in the nation in % of structurally deficient bridge deck area