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
(sq. meters)
Daily Crossings on All Bridges Number of Structurally Deficient Bridges Area of Structurally Deficient Bridges
(sq. meters)
Daily Crossings on Structurally Deficient Bridges
Rural Interstate 405 369,159 8,103,646 20 11,230 339,130
Rural arterial 642 413,009 5,712,314 37 18,401 355,265
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 Interstate 841 1,418,025 30,711,215 55 96,986 2,073,472
Urban freeway/expressway 319 337,132 8,360,985 23 19,713 600,341
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 collector 488 297,667 3,423,946 45 29,247 273,171
Urban local road 591 304,851 2,508,929 66 21,575 188,773
Total 11,284 6,487,111 94,517,674 1,240 502,238 7,132,522
Type of Work Number of Bridges Cost to Repair
(in millions)
Daily Crossings Area of Bridges
(sq. meters)
Bridge replacement 665 $453 1,987,475 149,264
Widening & rehabilitation 75 $87 1,294,624 43,862
Rehabilitation 1,009 $844 5,657,679 413,939
Deck rehabilitation/replacement 767 $1,498 9,482,327 750,219
Other structural work 168 $176 652,927 85,709
Total 2,684 $3,058 19,075,032 1,442,993

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.

10
Compared to 11 in 2020

in the nation in % of structurally deficient bridges

1. West Virginia 20.4%
9. North Dakota 11.2%
10. Michigan 11.0%
11. Oklahoma 9.9%

14
Compared to 16 in 2020

in the nation in # of structurally deficient bridges

1. Iowa 4,504
13. Kansas 1,277
14. Michigan 1,240
15. Mississippi 1,174

13
Compared to 10 in 2020

in the nation in % of structurally deficient bridge deck area

1. Rhode Island 19.5%
12. Missouri 8.4%
13. Michigan 7.7%
14. Connecticut 7.5%
Full State Ranking

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  • Source: 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.

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