Total bridges
523
Public highway bridges in Kent County
County profile · official public datasets
Kent County, MI
523 public highway bridges tracked in the FHWA National Bridge Inventory: 36.9% rated Good, 57.7% Fair, 5.4% Poor.
- 523
- Public bridges
- 36.9%
- Good condition
- 5.4%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Kent County posts a top-quartile lowest Poor-condition share among rated counties in the state across large county bridge inventory.
- Top 16%
- lowest Poor share in state
- 5.4%
- Poor-condition share
- 523
- public highway bridges
- 1975
- avg year built
Poor is an FHWA condition category from the lowest applicable component rating (4 or below), not a live crossing-safety or closure decision. Rankings cover counties with at least five public highway bridges.
Kent County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Kent County ranks #13 of 83 Michigan counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 5.4%). Kent County, Michigan contains 523 public highway bridges. Roughly 36.9% are rated “Good,” 57.7% “Fair,” and 5.4% “Poor.” Poor means the lowest applicable deck, superstructure, substructure, or culvert rating is 4 or below on the 0–9 NBI scale. It is a condition category, not a live safety or closure decision.
Responsible agencies inspect covered bridges on risk-based intervals under current NBIS rules and submit inventory data to FHWA annually. The list below shows every NBI-tracked bridge in the county. Use the “Sort by” controls to change the ordering, and click any row for its reported inspection date, traffic count, and condition fields.
Source: FHWA National Bridge Inventory. See methodology for full definitions.
Good condition
36.9%
193 of 523 rated 7-9
Fair condition
57.7%
302 of 523 rated 5-6
Poor condition
5.4%
28 of 523 rated 4 or below
In-state Poor-share rank
#13 of 83
Among Michigan counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 523 NBI-tracked bridges by lowest applicable component rating.
Good 36.9% (193)
Fair 57.7% (302)
Poor 5.4% (28)
Kent County's Poor-condition bridges carry 574,530 vehicle crossings a day
That is 6.8% of the county's reported daily bridge traffic on 5.4% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 20,519 crossings a day against 12,442 for a Good-condition one. A Poor rating is a condition category, not a closure or a live safety judgement; it means the lowest applicable component rating is 4 or below.
Computed over the 519 of 523 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
55.4% of Kent County's bridges have passed the 50-year mark
290 of the 523 bridges with a recorded construction year were built in 1974 or earlier. Age alone is not a defect: a well-maintained older bridge can rate Good, and 36.9% of this county's inventory does. Even so, this older cohort is the population from which future Poor ratings are drawn, which is why the age profile below matters alongside the condition split above.
Cutoff derives from the 2024 release year minus a 50-year design life. Source: FHWA National Bridge Inventory, 2024 release.
One structure carries 8.9% of the county's Poor-condition bridge traffic
I-296 (US-131) NB over US-131 BR (LEONARD), built 1961, carries 50,972 vehicles a day, the most of any Poor-rated structure here. The county's Poor-condition exposure is concentrated rather than evenly spread, so the 28-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 574,530 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Kent County's bridges were built
523 bridges with a recorded construction year, grouped by decade
- pre-1900 2
Built before 1900
2 bridges
- 1910s 2
1910–1919
2 bridges
- 1920s 22
1920–1929
22 bridges
- 1930s 13
1930–1939
13 bridges
- 1940s 10
1940–1949
10 bridges
- 1950s 13
1950–1959
13 bridges
- 1960s
1960–1969
188 bridges
- 1970s 71
1970–1979
71 bridges
- 1980s 39
1980–1989
39 bridges
- 1990s 38
1990–1999
38 bridges
- 2000s
2000–2009
104 bridges
- 2010s 14
2010–2019
14 bridges
- 2020s 7
2020–2029
7 bridges
What this shows Construction peaked in the 1960s, when 188 of the county's bridges still in the inventory were built, which is 35.9% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1975) matches the Michigan average (1976).
How Kent County compares with Michigan's closest counties by inventory size
The 5 Michigan counties nearest Kent County in number of bridges, with their condition splits. Its 5.4% Poor share is the 1st-lowest of these 6. Its average build year of 1975 against a peer-group mean of 1979 is in line with the group.
Showing the 5 closest of 82 Michigan counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Kent County (this page) | 523 | 36.9% | 57.7% | 5.4% | 1975 |
| Oakland County | 508 | 41.5% | 51% | 7.5% | 1982 |
| Macomb County | 417 | 42.7% | 49.6% | 7.7% | 1980 |
| Genesee County | 371 | 22.9% | 61.7% | 15.4% | 1968 |
| St. Clair County | 327 | 41.3% | 50.5% | 8.3% | 1985 |
| Saginaw County | 315 | 28.9% | 52.7% | 18.4% | 1979 |
Each share is of that county's own total tracked bridges; peers are the counties with 5 or more bridges whose inventory size is closest to Kent County's. Source: FHWA National Bridge Inventory, 2024 release.
Nationwide counties with similar inventory size or average build year
Two NBI-derived peer sets for Kent County, both outside Michigan so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside MI (523 bridges here).
- Madison County, IL · 523 bridges
- Rapides County, LA · 523 bridges
- Williamson County, TN · 520 bridges
- New Castle County, DE · 527 bridges
Similar average build year
Nearest mean year-built outside MI (1975 here).
- San Bernardino County, CA · avg 1975 · 1,422 bridges
- Lane County, OR · avg 1975 · 1,010 bridges
- Fulton County, GA · avg 1975 · 775 bridges
- Westmoreland County, PA · avg 1975 · 620 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Fair-condition bridges (302)
Read our methodology - how this data is sourced, computed, and verified.
Related
Data sourced from official public datasets. See our methodology for details. Retrieved and formatted by PlainBridges
Every figure on PlainBridges is rendered directly from federal source data, no number is typed in by an editor. This page draws directly on federal source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. NBI condition categories reflect the latest reported inventory record, not a live safety, closure, or travel decision.