Total bridges
289
Public highway bridges in Grundy County
County profile · official public datasets
Grundy County, IA
289 public highway bridges tracked in the FHWA National Bridge Inventory: 42.6% rated Good, 32.9% Fair, 24.6% Poor.
- 289
- Public bridges
- 42.6%
- Good condition
- 24.6%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Grundy County posts a higher-than-median Poor-condition share among rated counties in the state across mid-size county bridge inventory.
- 65th
- of 99 on Poor share
- 24.6%
- Poor-condition share
- 289
- 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.
Grundy County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Grundy County ranks #65 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 24.6%). Grundy County, Iowa contains 289 public highway bridges. Roughly 42.6% are rated “Good,” 32.9% “Fair,” and 24.6% “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
42.6%
123 of 289 rated 7-9
Fair condition
32.9%
95 of 289 rated 5-6
Poor condition
24.6%
71 of 289 rated 4 or below
In-state Poor-share rank
#65 of 99
Among Iowa counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 289 NBI-tracked bridges by lowest applicable component rating.
Good 42.6% (123)
Fair 32.9% (95)
Poor 24.6% (71)
Grundy County's Poor-condition bridges carry 15,133 vehicle crossings a day
That is 7.1% of the county's reported daily bridge traffic on 24.6% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 213 crossings a day against 1,229 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 289 of 289 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
32.5% of Grundy County's bridges have passed the 50-year mark
94 of the 289 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 42.6% 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 21.3% of the county's Poor-condition bridge traffic
IA 14 over BLACK HAWK CREEK, built 1931, carries 3,230 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 71-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 15,133 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Grundy County's bridges were built
289 bridges with a recorded construction year, grouped by decade
- 1900s 2
1900–1909
2 bridges
- 1910s 3
1910–1919
3 bridges
- 1920s 1
1920–1929
1 bridges
- 1930s 2
1930–1939
2 bridges
- 1940s 5
1940–1949
5 bridges
- 1950s
1950–1959
32 bridges
- 1960s 25
1960–1969
25 bridges
- 1970s
1970–1979
69 bridges
- 1980s
1980–1989
38 bridges
- 1990s
1990–1999
32 bridges
- 2000s
2000–2009
47 bridges
- 2010s 25
2010–2019
25 bridges
- 2020s 8
2020–2029
8 bridges
What this shows Construction peaked in the 1970s, when 69 of the county's bridges still in the inventory were built, which is 23.9% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1983) matches the Iowa average (1979).
How Grundy County compares with Iowa's closest counties by inventory size
The 5 Iowa counties nearest Grundy County in number of bridges, with their condition splits. Its 24.6% Poor share is the 5th-lowest of these 6. Its average build year of 1983 against a peer-group mean of 1978 is 5 years newer.
Showing the 5 closest of 98 Iowa counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Story County | 296 | 33.1% | 53% | 13.9% | 1968 |
| Cass County | 295 | 25.4% | 41% | 33.6% | 1976 |
| Delaware County | 293 | 39.2% | 53.9% | 6.8% | 1981 |
| Scott County | 291 | 34.7% | 55% | 10.3% | 1980 |
| Butler County | 289 | 58.1% | 26.6% | 15.2% | 1985 |
| Grundy County (this page) | 289 | 42.6% | 32.9% | 24.6% | 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 Grundy 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 Grundy County, both outside Iowa so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside IA (289 bridges here).
- Union County, AR · 289 bridges
- McKinley County, NM · 289 bridges
- Knox County, IN · 290 bridges
- Putnam County, IN · 290 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.
Fair-condition bridges (95)
LOCAL ROAD
FairOver: MUNNS CREEK
087162601, Grundy, IA
Built 1956 Load: 31.0 t ADT: 26
IA 175
FairOver: BRANCH BLACKHAWK CREEK
0.8 MILE W OF JCT SR T69, Grundy, IA
Built 1977 Load: 31.2 t ADT: 2,080
FM
FairOver: HAMMERS CREEK
089151202, Grundy, IA
Built 1981 Load: 31.2 t ADT: 34
LOCAL ROAD
FairOver: BRANCH BEAR CREEK
087183001, Grundy, IA
Built 1955 Load: 31.9 t ADT: 49
US 20 EB
FairOver: IA 14
AT JUNCTION IA 14, Grundy, IA
Built 2000 Load: 32.2 t ADT: 4,400
D 19 160TH ST
FairOver: SMALL STREAM
088160607, Grundy, IA
Built 1984 Load: 32.7 t ADT: 560
D19 160TH ST
FairOver: BR N BLACKHAWK CREEK
088150303, Grundy, IA
Built 1985 Load: 32.7 t ADT: 786
F AVE
FairOver: SMALL NATURAL STREAM
087181102, Grundy, IA
Built 1969 Load: 32.7 t ADT: 1,169
F AVE
FairOver: SMALL NATURAL STREAM
087181102, Grundy, IA
Built 1969 Load: 32.7 t ADT: 1,169
FM
FairOver: BR WOLF CREEK
086170102, Grundy, IA
Built 1977 Load: 32.7 t ADT: 69
LOCAL ROAD
FairOver: DOWD CREEK
086180901, Grundy, IA
Built 1978 Load: 32.7 t ADT: 49
LOCAL
FairOver: WOLF CREEK
086181001, Grundy, IA
Built 1975 Load: 32.7 t ADT: 49
LOCAL
FairOver: FORK OF DOWD CREEK
086181603, Grundy, IA
Built 1985 Load: 32.7 t ADT: 49
LOCAL
FairOver: BRANCH BLACK HAWK CREEK
087161802, Grundy, IA
Built 1994 Load: 32.7 t ADT: 69
FM
FairOver: MUNNS CREEK
087162202, Grundy, IA
Built 1994 Load: 32.7 t ADT: 628
FM
FairOver: BR BLACKHAWK CK
088152002, Grundy, IA
Built 1977 Load: 32.7 t ADT: 1,051
LOCAL
FairOver: BLACK HAWK CREEK
088160102, Grundy, IA
Built 1991 Load: 32.7 t ADT: 33
LOCAL
FairOver: BRANCH BLACKHAWK CREEK
088171102, Grundy, IA
Built 1988 Load: 32.7 t ADT: 33
205TH ST
FairOver: BLACKHAWK CREEK
088172703, Grundy, IA
Built 1993 Load: 32.7 t ADT: 452
FM
FairOver: BRANCH BLACKHAWK CREEK
088172704, Grundy, IA
Built 1988 Load: 32.7 t ADT: 34
LOCAL
FairOver: BRANCH BEAVER CREEK
088180904, Grundy, IA
Built 1988 Load: 32.7 t ADT: 70
LOCAL
FairOver: FORK OF BEAVER CREEK
088181502, Grundy, IA
Built 1984 Load: 32.7 t ADT: 44
FM
FairOver: BRANCH OF IOWA RIVER
088183102, Grundy, IA
Built 1987 Load: 32.7 t ADT: 79
LOCAL
FairOver: BRANCH BLACKHAWK CREEK
089153201, Grundy, IA
Built 1988 Load: 32.7 t ADT: 49
FM
FairOver: BEAVER CREEK BRANCH
089172702, Grundy, IA
Built 1970 Load: 32.7 t ADT: 69
FM
FairOver: BEAVER CREEK NORTH FORK
089181302, Grundy, IA
Built 1989 Load: 32.7 t ADT: 452
FM
FairOver: BEAVER CREEK NORTH FORK
089182401, Grundy, IA
Built 1990 Load: 32.7 t ADT: 373
LOCAL
FairOver: STREAM
089151401, Grundy, IA
Built 1977 Load: 33.0 t ADT: 97
LOCAL ROAD
FairOver: BRANCH BLACKHAWK CREEK
087150402, Grundy, IA
Built 1966 Load: 33.9 t ADT: 59
LOCAL
FairOver: BLACKHAWK CREEK
088161001, Grundy, IA
Built 1957 Load: 34.2 t ADT: 44
FM
FairOver: BRANCH BEAVER CREEK
089172301, Grundy, IA
Built 1970 Load: 36.1 t ADT: 501
LOCAL ROAD
FairOver: WOLF X CREEK
087182501, Grundy, IA
Built 1957 Load: 36.2 t ADT: 11
FM
FairOver: BEAVER CREEK
089172202, Grundy, IA
Built 1972 Load: 36.3 t ADT: 79
FM
FairOver: DRAINAGE DITCH
088182903, Grundy, IA
Built 1955 Load: 36.7 t ADT: 491
FM
FairOver: CREEK
089152301, Grundy, IA
Built 1966 Load: 36.9 t ADT: 707
FM
FairOver: WOLF CREEK BRANCH
086182401, Grundy, IA
Built 1989 Load: 37.2 t ADT: 59
LOCAL
FairOver: FK OF BLACKHAWK CREEK
087172401, Grundy, IA
Built 1997 Load: 38.8 t ADT: 44
US 20 EB
FairOver: T 19
AT JUNCTION WITH SR T19, Grundy, IA
Built 2003 Load: 38.8 t ADT: 4,550
FM
FairOver: BLACKHAWK CREEK BRANCH
088163303, Grundy, IA
Built 1964 Load: 40.7 t ADT: 550
FM
FairOver: WOLF CREEK
087183501, Grundy, IA
Built 1964 Load: 43.2 t ADT: 98
LOCAL RD
FairOver: BRANCH BLACKHAWK CREEK
089162401, Grundy, IA
Built 1957 Load: 43.3 t ADT: 29
CENTER ST (D67)
FairOver: WOLF CREEK
086173101, Grundy, IA
Built 1978 Load: 43.7 t ADT: 1,968
FM
FairOver: BLACKHAWK CREEK BRANCH
087160102, Grundy, IA
Built 1966 Load: 47.8 t ADT: 579
D19 160TH ST
FairOver: TRIB BLACKHAWK CREEK
088160101, Grundy, IA
Built 1984 Load: 51.7 t ADT: 786
MAIN ST
FairOver: WOLF CREEK
086173201, Grundy, IA
Built 1999 Load: 56.5 t ADT: 625
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.