Total bridges
225
Public highway bridges in Mahaska County
County profile · official public datasets
Mahaska County, IA
225 public highway bridges tracked in the FHWA National Bridge Inventory: 28.4% rated Good, 39.1% Fair, 32.4% Poor.
- 225
- Public bridges
- 28.4%
- Good condition
- 32.4%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Mahaska 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.
- 85th
- of 99 on Poor share
- 32.4%
- Poor-condition share
- 225
- public highway bridges
- 1972
- 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.
Mahaska County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Mahaska County ranks #85 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 32.4%). Mahaska County, Iowa contains 225 public highway bridges. Roughly 28.4% are rated “Good,” 39.1% “Fair,” and 32.4% “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
28.4%
64 of 225 rated 7-9
Fair condition
39.1%
88 of 225 rated 5-6
Poor condition
32.4%
73 of 225 rated 4 or below
In-state Poor-share rank
#85 of 99
Among Iowa counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 225 NBI-tracked bridges by lowest applicable component rating.
Good 28.4% (64)
Fair 39.1% (88)
Poor 32.4% (73)
Mahaska County's Poor-condition bridges carry 10,792 vehicle crossings a day
That is 6.2% of the county's reported daily bridge traffic on 32.6% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 148 crossings a day against 1,231 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 224 of 225 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
58.7% of Mahaska County's bridges have passed the 50-year mark
132 of the 225 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 28.4% 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 21.8% of the county's Poor-condition bridge traffic
IA 23 over TRIBUTARY OF CEDAR CREEK, built 1928, carries 2,350 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 73-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 10,792 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Mahaska County's bridges were built
225 bridges with a recorded construction year, grouped by decade
- 1900s 6
1900–1909
6 bridges
- 1920s 3
1920–1929
3 bridges
- 1930s 1
1930–1939
1 bridges
- 1940s 8
1940–1949
8 bridges
- 1950s
1950–1959
66 bridges
- 1960s
1960–1969
30 bridges
- 1970s 25
1970–1979
25 bridges
- 1980s 22
1980–1989
22 bridges
- 1990s
1990–1999
34 bridges
- 2000s 16
2000–2009
16 bridges
- 2010s 9
2010–2019
9 bridges
- 2020s 5
2020–2029
5 bridges
What this shows Construction peaked in the 1950s, when 66 of the county's bridges still in the inventory were built, which is 29.3% of those with a recorded year. That cohort is now 65 to 74 years old in the 2024 inventory. Its average build year is 1972, 7 years older than the Iowa average of 1979.
How Mahaska County compares with Iowa's closest counties by inventory size
The 5 Iowa counties nearest Mahaska County in number of bridges, with their condition splits. Its 32.4% Poor share is the 3rd-lowest of these 6. Its average build year of 1972 against a peer-group mean of 1975 is in line with the group.
Showing the 5 closest of 98 Iowa counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Jones County | 231 | 36.8% | 58.9% | 4.3% | 1981 |
| Franklin County | 228 | 44.7% | 42.1% | 13.2% | 1982 |
| Madison County | 225 | 16% | 46.7% | 37.3% | 1968 |
| Mahaska County (this page) | 225 | 28.4% | 39.1% | 32.4% | 1972 |
| Sac County | 224 | 35.7% | 30.8% | 33.5% | 1973 |
| Taylor County | 220 | 24.5% | 37.7% | 37.7% | 1973 |
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 Mahaska 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 Mahaska County, both outside Iowa so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside IA (225 bridges here).
- Dallas County, AL · 225 bridges
- Lincoln County, KS · 225 bridges
- Lenawee County, MI · 225 bridges
- Clay County, MN · 225 bridges
Similar average build year
Nearest mean year-built outside IA (1972 here).
- Santa Clara County, CA · avg 1972 · 964 bridges
- Madison County, AL · avg 1972 · 710 bridges
- Kern County, CA · avg 1972 · 668 bridges
- York County, PA · avg 1972 · 569 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Fair-condition bridges (88)
FM
FairOver: MITCHELL CREEK
076160905, Mahaska, IA
Built 1972 Load: 28.6 t ADT: 290
US 63 SB
FairOver: IA 163
AT JCT. OF IA 163, Mahaska, IA
Built 1996 Load: 29.0 t ADT: 2,750
LOCAL
FairOver: MUCHAKINOCK CREEK
074161305, Mahaska, IA
Built 1987 Load: 29.7 t ADT: 710
FM
FairOver: MIDDLE CREEK
076151606, Mahaska, IA
Built 1971 Load: 30.4 t ADT: 300
FM T-43
FairOver: S SKUNK RIVER
076171206, Mahaska, IA
Built 1977 Load: 30.4 t ADT: 120
LOCAL
FairOver: MIDDLE CREEK
077162102, Mahaska, IA
Built 1953 Load: 30.4 t ADT: 30
FM
FairOver: MIDDLE CREEK
077163503, Mahaska, IA
Built 1971 Load: 30.6 t ADT: 60
LOCAL
FairOver: STREAM
077152204, Mahaska, IA
Built 1965 Load: 31.0 t ADT: 50
LOCAL
FairOver: MUCHAKINOCK CREEK
074161117, Mahaska, IA
Built 1974 Load: 31.4 t ADT: 80
FM
FairOver: CEDAR CREEK
074151405, Mahaska, IA
Built 1957 Load: 32.3 t ADT: 120
US 63
FairOver: NENEBEC CREEK
0.2 mi. N of Jct. SR G71, Mahaska, IA
Built 1998 Load: 32.7 t ADT: 12,500
US 63
FairOver: LITTLE MUCHAKINOCK CREEK
0.2 MILES NORTH OF IA 163, Mahaska, IA
Built 1963 Load: 32.7 t ADT: 6,500
LOCAL
FairOver: DRAINAGE
074162403, Mahaska, IA
Built 1987 Load: 32.7 t ADT: 710
LOCAL
FairOver: S COAL CREEK
074171906, Mahaska, IA
Built 2005 Load: 32.7 t ADT: 60
FM
FairOver: TURKEY RUN
074172101, Mahaska, IA
Built 1983 Load: 32.7 t ADT: 610
FM
FairOver: TURKEY RUN
074172301, Mahaska, IA
Built 1994 Load: 32.7 t ADT: 610
FM
FairOver: SOUTH SKUNK RIVER
075141504, Mahaska, IA
Built 1982 Load: 32.7 t ADT: 330
FM
FairOver: SNYDER CREEK
075142206, Mahaska, IA
Built 1982 Load: 32.7 t ADT: 330
LOCAL
FairOver: SPRING CREEK
075152102, Mahaska, IA
Built 1986 Load: 32.7 t ADT: 840
LOCAL
FairOver: DRAINAGE
076143305, Mahaska, IA
Built 1988 Load: 32.7 t ADT: 50
LOCAL
FairOver: MIDDLE CREEK
076143408, Mahaska, IA
Built 1982 Load: 32.7 t ADT: 26
FM
FairOver: E BR BUCKLEY CREEK
077171006, Mahaska, IA
Built 1983 Load: 32.7 t ADT: 1,130
LOCAL
FairOver: DES MOINES RIVER
074162201, Mahaska, IA
Built 1987 Load: 32.7 t ADT: 710
IA 163
FairOver: LITTLE MUCHIKINOCK CREEK
2.4 MI. E OF JCT. IA 92, Mahaska, IA
Built 1995 Load: 32.7 t ADT: 7,800
IA 163
FairOver: MUCHAKINOK CREEK
1.2 MILES E OF JCT SR G5T, Mahaska, IA
Built 1997 Load: 32.7 t ADT: 12,200
FM
FairOver: LITTLE CREEK
077172216, Mahaska, IA
Built 1967 Load: 33.5 t ADT: 1,130
LOCAL
FairOver: N COAL CREEK
074170404, Mahaska, IA
Built 1950 Load: 33.7 t ADT: 60
FM
FairOver: DRAINAGE
077140101, Mahaska, IA
Built 1990 Load: 36.8 t ADT: 60
US 63
FairOver: MIDDLE CREEK
3.3 mi. S of jct. IA 146, Mahaska, IA
Built 1961 Load: 37.4 t ADT: 4,240
FM
FairOver: MIDDLE CREEK
076150803, Mahaska, IA
Built 1990 Load: 37.7 t ADT: 370
LOCAL
FairOver: BUCK CREEK
077150910, Mahaska, IA
Built 1988 Load: 38.7 t ADT: 20
FM
FairOver: STREAM
076150905, Mahaska, IA
Built 1962 Load: 41.5 t ADT: 370
IA 92
FairOver: SOUTH SKUNK RIVER
2.2 MI. W OF W JCT SR V13, Mahaska, IA
Built 1985 Load: 43.1 t ADT: 2,850
OLD IA 102
FairOver: MIDDLE CREEK
077162001, Mahaska, IA
Built 1962 Load: 47.9 t ADT: 1,550
FM
FairOver: S COAL CREEK
074172003, Mahaska, IA
Built 1994 Load: 48.2 t ADT: 610
US 63
FairOver: UP RR
0.1 MILES N OF JCT IA 146, Mahaska, IA
Built 1985 Load: 49.0 t ADT: 2,130
US 63
FairOver: BUCK CREEK
3.2 mi. N of Jct. IA 146, Mahaska, IA
Built 1985 Load: 50.1 t ADT: 1,470
FM
FairOver: CEDAR CREEK
076141201, Mahaska, IA
Built 2000 Load: 53.5 t ADT: 370
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.