Total bridges
206
Public highway bridges in Audubon County
County profile · official public datasets
Audubon County, IA
206 public highway bridges tracked in the FHWA National Bridge Inventory: 33.5% rated Good, 48.1% Fair, 18.4% Poor.
- 206
- Public bridges
- 33.5%
- Good condition
- 18.4%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Audubon County pairs a better-than-median Poor-condition share among rated counties in the state with an older average build year than the state inventory.
- Top 46%
- lowest Poor share in state
- 18.4%
- Poor-condition share
- 206
- public highway bridges
- 1968
- 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.
Audubon County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Audubon County ranks #46 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 18.4%). Audubon County, Iowa contains 206 public highway bridges. Roughly 33.5% are rated “Good,” 48.1% “Fair,” and 18.4% “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
33.5%
69 of 206 rated 7-9
Fair condition
48.1%
99 of 206 rated 5-6
Poor condition
18.4%
38 of 206 rated 4 or below
In-state Poor-share rank
#46 of 99
Among Iowa counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 206 NBI-tracked bridges by lowest applicable component rating.
Good 33.5% (69)
Fair 48.1% (99)
Poor 18.4% (38)
Audubon County's Poor-condition bridges carry 1,856 vehicle crossings a day
That is 4% of the county's reported daily bridge traffic on 18.6% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 49 crossings a day against 250 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 204 of 206 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
58.7% of Audubon County's bridges have passed the 50-year mark
121 of the 206 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 33.5% 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 33.2% of the county's Poor-condition bridge traffic
EDGERTON ST over DRAINAGE, built 1960, carries 616 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 38-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 1,856 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Audubon County's bridges were built
206 bridges with a recorded construction year, grouped by decade
- 1900s 2
1900–1909
2 bridges
- 1910s 1
1910–1919
1 bridges
- 1920s
1920–1929
17 bridges
- 1930s
1930–1939
31 bridges
- 1940s
1940–1949
17 bridges
- 1950s
1950–1959
21 bridges
- 1960s
1960–1969
17 bridges
- 1970s
1970–1979
25 bridges
- 1980s
1980–1989
16 bridges
- 1990s
1990–1999
19 bridges
- 2000s
2000–2009
19 bridges
- 2010s
2010–2019
15 bridges
- 2020s 6
2020–2029
6 bridges
What this shows Construction peaked in the 1930s, when 31 of the county's bridges still in the inventory were built, which is 15% of those with a recorded year. That cohort is now 85 to 94 years old in the 2024 inventory. Its average build year is 1968, 11 years older than the Iowa average of 1979.
How Audubon County compares with Iowa's closest counties by inventory size
The 5 Iowa counties nearest Audubon County in number of bridges, with their condition splits. Its 18.4% Poor share is the 3rd-lowest of these 6. Its average build year of 1968 against a peer-group mean of 1978 is 10 years older.
Showing the 5 closest of 98 Iowa counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Howard County | 210 | 41.9% | 35.2% | 22.9% | 1984 |
| Montgomery County | 210 | 21% | 53.8% | 25.2% | 1973 |
| Shelby County | 207 | 36.2% | 54.1% | 9.7% | 1979 |
| Washington County | 207 | 39.6% | 44.4% | 15.9% | 1980 |
| Audubon County (this page) | 206 | 33.5% | 48.1% | 18.4% | 1968 |
| Pocahontas County | 201 | 19.4% | 55.2% | 25.4% | 1974 |
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 Audubon 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 Audubon County, both outside Iowa so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside IA (206 bridges here).
- Dale County, AL · 206 bridges
- Henry County, IN · 206 bridges
- Bourbon County, KS · 206 bridges
- Pemiscot County, MO · 206 bridges
Similar average build year
Nearest mean year-built outside IA (1968 here).
- Montgomery County, PA · avg 1968 · 828 bridges
- San Joaquin County, CA · avg 1968 · 644 bridges
- Providence County, RI · avg 1968 · 476 bridges
- Imperial County, CA · avg 1968 · 444 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Good-condition bridges (69)
US 71
GoodOver: BLUEGRASS CREEK
1.4 mi. S of Jct. SR F32, Audubon, IA
Built 2006 Load: 38.5 t ADT: 3,080
LARK AVE
GoodOver: CREEK
0.25 Mile S. Co Hwy F32, Audubon, IA
Built 2017 Load: 38.6 t ADT: 29
LARK AVE
GoodOver: BR E NISHNABOTNA R
FM 081351202, Audubon, IA
Built 2018 Load: 38.6 t ADT: 50
LOCAL
GoodOver: E NISHNABOTNA RIVER
080352501, Audubon, IA
Built 1998 Load: 38.8 t ADT: 103
130TH ST
GoodOver: CREEK
081 34 24 01, Audubon, IA
Built 2021 Load: 38.8 t ADT: 20
GOLDFINCH AVE
GoodOver: CREEK
081350702, Audubon, IA
Built 2021 Load: 38.8 t ADT: 50
SOUTH ST
GoodOver: BLUE GRASS CREEK
City of Audubon, Audubon, IA
Built 2003 Load: 39.6 t ADT: 1,423
W BROADWAY
GoodOver: BLUEGRASS CREEK
675 West of US HWY 71, Audubon, IA
Built 2009 Load: 39.6 t ADT: 311
F 16 120TH ST
GoodOver: E NISHNABOTNA RIVER
FM 081351301, Audubon, IA
Built 2019 Load: 39.9 t ADT: 40
FM
GoodOver: CREEK
000000000, Audubon, IA
Built 2010 Load: 40.0 t ADT: 34
FM
GoodOver: CREEK
081342502, Audubon, IA
Built 1932 Load: 40.0 t ADT: 15
NORTH DIVISION ST
GoodOver: BLUE GRASS CREEK
N Division St W. of US71, Audubon, IA
Built 2022 Load: 40.2 t ADT: 271
N36 PHEASANT AVE
GoodOver: DAVIDS CREEK
FM 079340302, Audubon, IA
Built 2021 Load: 41.5 t ADT: 240
IA 44
GoodOver: INDIAN CREEK
0.4 mi. E OF JCT. IA 173, Audubon, IA
Built 1980 Load: 42.3 t ADT: 880
PHEASANT AVE
GoodOver: CREEK
081340302, Audubon, IA
Built 2019 Load: 49.7 t ADT: 35
FM
GoodOver: BEAVER CREEK
081340203, Audubon, IA
Built 1991 Load: 49.8 t ADT: 11
F58 LITTLEFIELD DR
GoodOver: CREEK
FM 078340802, Audubon, IA
Built 2005 Load: 52.9 t ADT: 548
FM
GoodOver: ELK HORN CREEK
078360405, Audubon, IA
Built 2002 Load: 55.3 t ADT: 20
FM F-58
GoodOver: CROOKED CREEK
078342702, Audubon, IA
Built 2003 Load: 58.1 t ADT: 278
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.