Total bridges
186
Public highway bridges in Adams County
County profile · official public datasets
Adams County, IA
186 public highway bridges tracked in the FHWA National Bridge Inventory: 10.2% rated Good, 45.2% Fair, 44.6% Poor.
- 186
- Public bridges
- 10.2%
- Good condition
- 44.6%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Adams County pairs a higher-than-median Poor-condition share among rated counties in the state with an older average build year than the state inventory.
- 99th
- of 99 on Poor share
- 44.6%
- Poor-condition share
- 186
- public highway bridges
- 1967
- 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.
Adams County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Adams County ranks #99 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 44.6%). Adams County, Iowa contains 186 public highway bridges. Roughly 10.2% are rated “Good,” 45.2% “Fair,” and 44.6% “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
10.2%
19 of 186 rated 7-9
Fair condition
45.2%
84 of 186 rated 5-6
Poor condition
44.6%
83 of 186 rated 4 or below
In-state Poor-share rank
#99 of 99
Among Iowa counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 186 NBI-tracked bridges by lowest applicable component rating.
Good 10.2% (19)
Fair 45.2% (84)
Poor 44.6% (83)
Adams County's Poor-condition bridges carry 5,302 vehicle crossings a day
That is 14.2% of the county's reported daily bridge traffic on 44.6% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 64 crossings a day against 584 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 186 of 186 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
71% of Adams County's bridges have passed the 50-year mark
132 of the 186 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 10.2% 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 14.8% of the county's Poor-condition bridge traffic
2ND STREET over DREYS DITCH, built 1920, carries 787 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 83-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 5,302 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Adams County's bridges were built
186 bridges with a recorded construction year, grouped by decade
- 1900s 4
1900–1909
4 bridges
- 1910s 1
1910–1919
1 bridges
- 1920s 5
1920–1929
5 bridges
- 1930s 8
1930–1939
8 bridges
- 1940s 2
1940–1949
2 bridges
- 1950s
1950–1959
28 bridges
- 1960s
1960–1969
69 bridges
- 1970s
1970–1979
34 bridges
- 1980s 14
1980–1989
14 bridges
- 1990s 4
1990–1999
4 bridges
- 2000s 9
2000–2009
9 bridges
- 2010s 6
2010–2019
6 bridges
- 2020s 2
2020–2029
2 bridges
What this shows Construction peaked in the 1960s, when 69 of the county's bridges still in the inventory were built, which is 37.1% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year is 1967, 12 years older than the Iowa average of 1979.
How Adams County compares with Iowa's closest counties by inventory size
The 5 Iowa counties nearest Adams County in number of bridges, with their condition splits. Its 44.6% Poor share is the 6th-lowest of these 6. Its average build year of 1967 against a peer-group mean of 1978 is 11 years older.
Showing the 5 closest of 98 Iowa counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Wapello County | 190 | 45.8% | 39.5% | 14.7% | 1987 |
| Adams County (this page) | 186 | 10.2% | 45.2% | 44.6% | 1967 |
| Osceola County | 185 | 38.4% | 53% | 8.6% | 1965 |
| Mills County | 184 | 29.3% | 51.6% | 19% | 1976 |
| Appanoose County | 183 | 41% | 27.9% | 31.1% | 1981 |
| Keokuk County | 183 | 34.4% | 45.9% | 19.7% | 1980 |
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 Adams 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 Adams County, both outside Iowa so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside IA (186 bridges here).
- Fayette County, AL · 186 bridges
- Marion County, MO · 186 bridges
- Coshocton County, OH · 186 bridges
- Montgomery County, TN · 186 bridges
Similar average build year
Nearest mean year-built outside IA (1967 here).
- Los Angeles County, CA · avg 1967 · 3,547 bridges
- Allegheny County, PA · avg 1967 · 1,294 bridges
- Sonoma County, CA · avg 1967 · 609 bridges
- Merced County, CA · avg 1967 · 528 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Good-condition bridges (19)
MULBERRY AVE
GoodOver: W BRANCH 102 RIVER
071332904, Adams, IA
Built 1980 Load: 22.3 t ADT: 26
IA 148
GoodOver: OVER BNSF RR
0.6 MI. N OF JCT. IA 34, Adams, IA
Built 1976 Load: 29.6 t ADT: 3,580
IA 148
GoodOver: MIDDLE NODAWAY RIVER
1.8 MI. S OF Jct. SR H-20, Adams, IA
Built 1959 Load: 32.0 t ADT: 770
LOOMIS ST
GoodOver: EAST NODAWAY RIVER
071340300, Adams, IA
Built 2012 Load: 32.4 t ADT: 820
US 34
GoodOver: PLATTE RIVER
1.3 MI. W OF JCT. 25, Adams, IA
Built 2014 Load: 32.4 t ADT: 2,390
H54 260TH ST
GoodOver: BNSF RR
071351905, Adams, IA
Built 2017 Load: 32.4 t ADT: 439
FM-150TH STREET
GoodOver: E FORK E NODAWAY RIVER
733332, Adams, IA
Built 2008 Load: 32.4 t ADT: 399
QUINCE AVE
GoodOver: EAST NODAWAY RIVER
000000000, Adams, IA
Built 2009 Load: 32.7 t ADT: 450
FM-125TH STREET
GoodOver: STREAM
073341303, Adams, IA
Built 2004 Load: 32.7 t ADT: 170
H34 HULL ST
GoodOver: STREAM
072343400, Adams, IA
Built 2022 Load: 34.3 t ADT: 875
FM-BIRCH AVENUE
GoodOver: MIDDLE NODAWAY RIVER
072352102, Adams, IA
Built 1985 Load: 34.6 t ADT: 26
145TH RD
GoodOver: STREAM
073342906, Adams, IA
Built 2015 Load: 37.9 t ADT: 15
HICKORY AVENUE
GoodOver: KEMP CREEK
072342906, Adams, IA
Built 2006 Load: 39.8 t ADT: 71
240TH STREET
GoodOver: SAYLINGS CREEK
071321601, Adams, IA
Built 2008 Load: 40.8 t ADT: 11
H 33 180TH STREET
GoodOver: MOUNT ZION BRANCH
072331301, Adams, IA
Built 2021 Load: 43.7 t ADT: 409
HICKORY AVENUE
GoodOver: WEST FORK 102 RIVER
071342008, Adams, IA
Built 2004 Load: 45.5 t ADT: 29
H33 180TH ST
GoodOver: EAST NODAWAY RIVER
072321701, Adams, IA
Built 2015 Load: 49.6 t ADT: 409
H20 125TH ST
GoodOver: MIDDLE NODAWAY RIVER
073341409, Adams, IA
Built 2015 Load: 50.2 t ADT: 170
TULIP AVENUE
GoodOver: SAYLINGS CREEK
071321602, Adams, IA
Built 2002 Load: 51.6 t ADT: 40
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.