Total bridges
254
Public highway bridges in Ottawa County
County profile · official public datasets
Ottawa County, MI
254 public highway bridges tracked in the FHWA National Bridge Inventory: 40.9% rated Good, 52.8% Fair, 6.3% Poor.
- 254
- Public bridges
- 40.9%
- Good condition
- 6.3%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Ottawa County posts a top-quartile lowest Poor-condition share among rated counties in the state across mid-size county bridge inventory.
- Top 24%
- lowest Poor share in state
- 6.3%
- Poor-condition share
- 254
- public highway bridges
- 1977
- 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.
Ottawa County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Ottawa County ranks #20 of 83 Michigan counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 6.3%). Ottawa County, Michigan contains 254 public highway bridges. Roughly 40.9% are rated “Good,” 52.8% “Fair,” and 6.3% “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
40.9%
104 of 254 rated 7-9
Fair condition
52.8%
134 of 254 rated 5-6
Poor condition
6.3%
16 of 254 rated 4 or below
In-state Poor-share rank
#20 of 83
Among Michigan counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 254 NBI-tracked bridges by lowest applicable component rating.
Good 40.9% (104)
Fair 52.8% (134)
Poor 6.3% (16)
Ottawa County's Poor-condition bridges carry 74,334 vehicle crossings a day
That is 2.8% of the county's reported daily bridge traffic on 6.3% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 4,646 crossings a day against 8,357 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 254 of 254 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
57.9% of Ottawa County's bridges have passed the 50-year mark
147 of the 254 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 40.9% 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 31.4% of the county's Poor-condition bridge traffic
US-31 SB over BLACK RIVER, built 1958, carries 23,373 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 16-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 74,334 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Ottawa County's bridges were built
254 bridges with a recorded construction year, grouped by decade
- 1900s 1
1900–1909
1 bridges
- 1920s 8
1920–1929
8 bridges
- 1930s 3
1930–1939
3 bridges
- 1940s 6
1940–1949
6 bridges
- 1950s 29
1950–1959
29 bridges
- 1960s 20
1960–1969
20 bridges
- 1970s
1970–1979
106 bridges
- 1980s 13
1980–1989
13 bridges
- 1990s 19
1990–1999
19 bridges
- 2000s 26
2000–2009
26 bridges
- 2010s 20
2010–2019
20 bridges
- 2020s 3
2020–2029
3 bridges
What this shows Construction peaked in the 1970s, when 106 of the county's bridges still in the inventory were built, which is 41.7% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1977) matches the Michigan average (1976).
How Ottawa County compares with Michigan's closest counties by inventory size
The 5 Michigan counties nearest Ottawa County in number of bridges, with their condition splits. Its 6.3% Poor share is the 3rd-lowest of these 6. Its average build year of 1977 against a peer-group mean of 1977 is in line with the group.
Showing the 5 closest of 82 Michigan counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Berrien County | 272 | 27.6% | 66.5% | 5.9% | 1979 |
| Washtenaw County | 262 | 23.3% | 56.5% | 20.2% | 1975 |
| Ottawa County (this page) | 254 | 40.9% | 52.8% | 6.3% | 1977 |
| Allegan County | 244 | 24.2% | 59% | 16.8% | 1978 |
| Tuscola County | 242 | 33.9% | 61.2% | 5% | 1980 |
| Ingham County | 241 | 15.8% | 68.9% | 15.4% | 1972 |
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 Ottawa 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 Ottawa County, both outside Michigan so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside MI (254 bridges here).
- Manatee County, FL · 254 bridges
- Wagoner County, OK · 254 bridges
- Coos County, OR · 254 bridges
- Adams County, PA · 254 bridges
Similar average build year
Nearest mean year-built outside MI (1977 here).
- San Diego County, CA · avg 1977 · 1,632 bridges
- King County, WA · avg 1977 · 1,238 bridges
- Riverside County, CA · avg 1977 · 1,117 bridges
- Shelby County, TN · avg 1977 · 1,077 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
All bridges (254)
ADAMS STREET
PoorOver: BLACK RIVER TRIBUTARY
0.59 MILES W OF 64TH AVE, Ottawa, MI
Built 1973 Load: 37.9 t ADT: 7,350
WEST OLIVE RD
PoorOver: PIGEON CREEK
SEC 12 PORT SHELDON TWP, Ottawa, MI
Built 1920 Load: 43.1 t ADT: 1,050
US-31 SB
PoorOver: BLACK RIVER
0.4 MI N OF M-21, Ottawa, MI
Built 1958 Load: 51.5 t ADT: 23,373
48TH AVENUE
PoorOver: BEAVER CREEK
SECTION 7 WRIGHT TWP, Ottawa, MI
Built 1975 Load: 52.8 t ADT: 785
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.