Total bridges
306
Public highway bridges in Adair County
County profile · official public datasets
Adair County, IA
306 public highway bridges tracked in the FHWA National Bridge Inventory: 46.7% rated Good, 39.9% Fair, 13.4% Poor.
- 306
- Public bridges
- 46.7%
- Good condition
- 13.4%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Adair County posts a better-than-median Poor-condition share among rated counties in the state across mid-size county bridge inventory.
- Top 28%
- lowest Poor share in state
- 13.4%
- Poor-condition share
- 306
- public highway bridges
- 1983
- 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.
Adair County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Adair County ranks #28 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 13.4%). Adair County, Iowa contains 306 public highway bridges. Roughly 46.7% are rated “Good,” 39.9% “Fair,” and 13.4% “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
46.7%
143 of 306 rated 7-9
Fair condition
39.9%
122 of 306 rated 5-6
Poor condition
13.4%
41 of 306 rated 4 or below
In-state Poor-share rank
#28 of 99
Among Iowa counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 306 NBI-tracked bridges by lowest applicable component rating.
Good 46.7% (143)
Fair 39.9% (122)
Poor 13.4% (41)
Adair County's Poor-condition bridges carry 1,794 vehicle crossings a day
That is 0.5% of the county's reported daily bridge traffic on 13.4% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 44 crossings a day against 485 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 306 of 306 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
40.5% of Adair County's bridges have passed the 50-year mark
124 of the 306 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 46.7% 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 21.6% of the county's Poor-condition bridge traffic
3RD ST over OVER ABANDON RR, built 1900, carries 387 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 41-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 1,794 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Adair County's bridges were built
306 bridges with a recorded construction year, grouped by decade
- 1900s 9
1900–1909
9 bridges
- 1910s 5
1910–1919
5 bridges
- 1920s 2
1920–1929
2 bridges
- 1930s 4
1930–1939
4 bridges
- 1940s 17
1940–1949
17 bridges
- 1950s
1950–1959
57 bridges
- 1960s 24
1960–1969
24 bridges
- 1970s 14
1970–1979
14 bridges
- 1980s 10
1980–1989
10 bridges
- 1990s 20
1990–1999
20 bridges
- 2000s
2000–2009
71 bridges
- 2010s
2010–2019
63 bridges
- 2020s 10
2020–2029
10 bridges
What this shows Construction peaked in the 2000s, when 71 of the county's bridges still in the inventory were built, which is 23.2% of those with a recorded year. That cohort is now 15 to 24 years old in the 2024 inventory. Its average build year (1983) matches the Iowa average (1979).
How Adair County compares with Iowa's closest counties by inventory size
The 5 Iowa counties nearest Adair County in number of bridges, with their condition splits. Its 13.4% Poor share is the 3rd-lowest of these 6. Its average build year of 1983 against a peer-group mean of 1981 is in line with the group.
Showing the 5 closest of 98 Iowa counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Buchanan County | 316 | 42.4% | 50.9% | 6.6% | 1985 |
| Adair County (this page) | 306 | 46.7% | 39.9% | 13.4% | 1983 |
| Marshall County | 304 | 32.9% | 23.7% | 43.4% | 1970 |
| Chickasaw County | 302 | 42.1% | 30.1% | 27.8% | 1986 |
| Cedar County | 301 | 42.9% | 37.5% | 19.6% | 1983 |
| Crawford County | 301 | 42.5% | 48.5% | 9% | 1982 |
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 Adair 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 Adair County, both outside Iowa so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside IA (306 bridges here).
- La Paz County, AZ · 306 bridges
- Greene County, PA · 306 bridges
- Greene County, TN · 306 bridges
- Grant County, WA · 306 bridges
Similar average build year
Nearest mean year-built outside IA (1983 here).
- Dallas County, TX · avg 1983 · 3,230 bridges
- Bexar County, TX · avg 1983 · 2,342 bridges
- Sedgwick County, KS · avg 1983 · 1,333 bridges
- Will County, IL · avg 1983 · 649 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
All bridges (306)
LOCAL
PoorOver: BATTLE CREEK
075300601, Adair, IA
Built 1958 Load: 22.8 t ADT: 15
LOCAL
PoorOver: CREEK
075322703, Adair, IA
Built 1954 Load: 23.2 t ADT: 62
FM
PoorOver: NINE MILE RUN
076332301, Adair, IA
Built 1961 Load: 24.1 t ADT: 45
LOCAL
PoorOver: RUTT BRANCH
075331202, Adair, IA
Built 1960 Load: 25.6 t ADT: 62
LOCAL
PoorOver: STREAM
077300101, Adair, IA
Built 1947 Load: 32.7 t ADT: 11
LOCAL
PoorOver: STREAM
074333639, Adair, IA
Built 1900 Load: 32.7 t ADT: 11
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.