Total bridges
337
Public highway bridges in Tama County
County profile · official public datasets
Tama County, IA
337 public highway bridges tracked in the FHWA National Bridge Inventory: 34.4% rated Good, 31.2% Fair, 34.4% Poor.
- 337
- Public bridges
- 34.4%
- Good condition
- 34.4%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Tama County posts a higher-than-median Poor-condition share among rated counties in the state across mid-size county bridge inventory.
- 91st
- of 99 on Poor share
- 34.4%
- Poor-condition share
- 337
- public highway bridges
- 1976
- 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.
Tama County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Tama County ranks #91 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 34.4%). Tama County, Iowa contains 337 public highway bridges. Roughly 34.4% are rated “Good,” 31.2% “Fair,” and 34.4% “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
34.4%
116 of 337 rated 7-9
Fair condition
31.2%
105 of 337 rated 5-6
Poor condition
34.4%
116 of 337 rated 4 or below
In-state Poor-share rank
#91 of 99
Among Iowa counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 337 NBI-tracked bridges by lowest applicable component rating.
Good 34.4% (116)
Fair 31.2% (105)
Poor 34.4% (116)
Tama County's Poor-condition bridges carry 22,557 vehicle crossings a day
That is 12.7% of the county's reported daily bridge traffic on 34.6% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 194 crossings a day against 1,091 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 335 of 337 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
42.1% of Tama County's bridges have passed the 50-year mark
142 of the 337 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 34.4% 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 12.8% of the county's Poor-condition bridge traffic
BUS US 30 over DEER CREEK, built 1953, carries 2,887 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 116-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 22,557 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Tama County's bridges were built
337 bridges with a recorded construction year, grouped by decade
- pre-1900 2
Built before 1900
2 bridges
- 1900s 7
1900–1909
7 bridges
- 1910s 10
1910–1919
10 bridges
- 1920s 12
1920–1929
12 bridges
- 1930s 10
1930–1939
10 bridges
- 1940s
1940–1949
29 bridges
- 1950s
1950–1959
28 bridges
- 1960s
1960–1969
33 bridges
- 1970s
1970–1979
24 bridges
- 1980s
1980–1989
49 bridges
- 1990s
1990–1999
42 bridges
- 2000s
2000–2009
44 bridges
- 2010s
2010–2019
36 bridges
- 2020s 11
2020–2029
11 bridges
What this shows Construction peaked in the 1980s, when 49 of the county's bridges still in the inventory were built, which is 14.5% of those with a recorded year. That cohort is now 35 to 44 years old in the 2024 inventory. Its average build year (1976) matches the Iowa average (1979).
How Tama County compares with Iowa's closest counties by inventory size
The 5 Iowa counties nearest Tama County in number of bridges, with their condition splits. Its 34.4% Poor share is the 6th-lowest of these 6. Its average build year of 1976 against a peer-group mean of 1980 is in line with the group.
Showing the 5 closest of 98 Iowa counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Fayette County | 362 | 35.1% | 40.3% | 24.6% | 1974 |
| Dubuque County | 346 | 50.6% | 40.8% | 8.7% | 1989 |
| Winneshiek County | 342 | 37.1% | 45.3% | 17.5% | 1967 |
| Tama County (this page) | 337 | 34.4% | 31.2% | 34.4% | 1976 |
| Buchanan County | 316 | 42.4% | 50.9% | 6.6% | 1985 |
| Adair County | 306 | 46.7% | 39.9% | 13.4% | 1983 |
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 Tama 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 Tama County, both outside Iowa so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside IA (337 bridges here).
- Placer County, CA · 337 bridges
- Cowley County, KS · 337 bridges
- Ouachita County, LA · 337 bridges
- Windham County, VT · 337 bridges
Similar average build year
Nearest mean year-built outside IA (1976 here).
- Marion County, IN · avg 1976 · 958 bridges
- Mohave County, AZ · avg 1976 · 641 bridges
- Comanche County, OK · avg 1976 · 593 bridges
- Prince George's County, MD · avg 1976 · 576 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Poor-condition bridges (116)
LOCAL
PoorOver: DEVILS RUN
085160802, Tama, IA
Built 1940 Load: 28.4 t ADT: 70
CENTER ST
PoorOver: DEER CREEK
084161401, Tama, IA
Built 1982 Load: 28.8 t ADT: 1,019
IRR-FM
PoorOver: IOWA RIVER
083153007, Tama, IA
Built 1988 Load: 29.4 t ADT: 619
LOCAL
PoorOver: KIBBE CREEK
084141002, Tama, IA
Built 1991 Load: 30.2 t ADT: 49
FM
PoorOver: BRANCH SALT CREEK
083132004, Tama, IA
Built 1970 Load: 30.4 t ADT: 432
FM
PoorOver: SO BRANCH SALT CREEK
084133202, Tama, IA
Built 1969 Load: 30.4 t ADT: 363
FM
PoorOver: BRANCH TWELVE MILE CREEK
086141409, Tama, IA
Built 1967 Load: 30.4 t ADT: 196
LOCAL
PoorOver: JORDAN CREEK
084152201, Tama, IA
Built 1940 Load: 31.0 t ADT: 39
FM
PoorOver: BRANCH SALT CREEK
084130603, Tama, IA
Built 1996 Load: 31.4 t ADT: 344
FM
PoorOver: IOWA RIVER
082132002, Tama, IA
Built 1968 Load: 31.6 t ADT: 786
FM
PoorOver: SMALL STREAM
086152401, Tama, IA
Built 1981 Load: 33.0 t ADT: 216
E66
PoorOver: SALT CREEK
082132403, Tama, IA
Built 1976 Load: 33.9 t ADT: 638
LOCAL
PoorOver: BRANCH IOWA RIVER
082140603, Tama, IA
Built 1983 Load: 35.6 t ADT: 11
E66
PoorOver: PLAGUE MINE CREEK
082131603, Tama, IA
Built 1976 Load: 38.3 t ADT: 638
IRR-FM
PoorOver: BENNETT CREEK
083153104, Tama, IA
Built 1944 Load: 39.2 t ADT: 59
FM
PoorOver: SO BRANCH SALT CREEK
084151203, Tama, IA
Built 1996 Load: 60.6 t ADT: 344
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.