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.
All bridges (289)
L AVE
GoodOver: BLACK HAWK CREEK
088171102, Grundy, IA
Built 2022 Load: 32.7 t ADT: 33
X AVENUE
GoodOver: US 20
2.0 MILES WEST OF SR D18, Grundy, IA
Built 1999 Load: 32.7 t ADT: 59
LUITJENS LANE
GoodOver: FORK OF BLACKHAWK CREEK
088150501, Grundy, IA
Built 1999 Load: 32.7 t ADT: 27
FM
GoodOver: SMALL STREAM
088160302, Grundy, IA
Built 1999 Load: 32.7 t ADT: 69
165TH STREET
GoodOver: BR BEAVER CREEK
088180205, Grundy, IA
Built 2003 Load: 32.7 t ADT: 59
T-19
GoodOver: DRAINAGE
088180212, Grundy, IA
Built 2003 Load: 32.7 t ADT: 2,082
US 20 EB
GoodOver: STREAM
0.9 MILE W OF JCT SR T55, Grundy, IA
Built 2000 Load: 33.1 t ADT: 6,750
WB US 20
GoodOver: SR T55
AT JUNCTION WITH SR T55, Grundy, IA
Built 2000 Load: 33.6 t ADT: 6,500
D55 (290TH ST)
GoodOver: BRANCH WOLF CREEK
86171101, Grundy, IA
Built 2013 Load: 33.7 t ADT: 44
120TH ST
GoodOver: N FORK BEAVER CREEK
089181501, Grundy, IA
Built 2016 Load: 33.7 t ADT: 29
US 20 EB
GoodOver: SR T55
AT JUNCTION WITH SR T55, Grundy, IA
Built 2000 Load: 34.0 t ADT: 6,500
US 20 WB
GoodOver: IA 14
AT JUNCTION WITH IA 14, Grundy, IA
Built 2000 Load: 34.0 t ADT: 4,400
FM
GoodOver: BR N BLACKHAWK CREEK
088160101, Grundy, IA
Built 2004 Load: 34.3 t ADT: 786
IA 175
GoodOver: MOSQUITO CREEK
1.2 MILES W OF JCT SR T65, Grundy, IA
Built 1977 Load: 34.4 t ADT: 1,820
LOCAL
GoodOver: BR HAMMERS CREEK
089151402, Grundy, IA
Built 2002 Load: 34.7 t ADT: 29
US 20 WB
GoodOver: STREAM
0.9 MILES W OF JCT SR T55, Grundy, IA
Built 2000 Load: 34.7 t ADT: 6,800
US 20 WB
GoodOver: S BEAVER CREEK
3.5 MILES W OF JCT SR T19, Grundy, IA
Built 2003 Load: 34.7 t ADT: 4,900
US 20 EB
GoodOver: S BEAVER CREEK
3.5 MILES W OF JCT SR T19, Grundy, IA
Built 2003 Load: 34.7 t ADT: 4,900
T47 Q AVE
GoodOver: MOSQUITO CREEK
087163402, Grundy, IA
Built 2022 Load: 35.0 t ADT: 628
US 20 WB
GoodOver: H AVENUE
2.0 MILES EAST JCT SR T19, Grundy, IA
Built 2003 Load: 35.3 t ADT: 5,000
US 20 EB
GoodOver: H AVENUE
2.0 mi. E of jct SR T19, Grundy, IA
Built 2003 Load: 35.3 t ADT: 5,000
EB US 20 RAMP B
GoodOver: STREAM
0.1 MILE W OF JCT SR T55, Grundy, IA
Built 2000 Load: 35.6 t ADT: 270
FM
GoodOver: DOWD CREEK
087183402, Grundy, IA
Built 1998 Load: 35.9 t ADT: 29
COUNTY ROAD
GoodOver: BRANCH BEAVER CREEK
089180702, Grundy, IA
Built 1998 Load: 35.9 t ADT: 20
LOCAL ROAD
GoodOver: BRANCH OF HAMMERS CREEK
089150201, Grundy, IA
Built 1999 Load: 36.3 t ADT: 29
T47 (Q AVE)
GoodOver: US 20
3.0 MILES E OF JCT IA 14, Grundy, IA
Built 1999 Load: 36.8 t ADT: 69
LOCAL ROAD
GoodOver: BRANCH OF HAMMERS CREEK
089150301, Grundy, IA
Built 2007 Load: 37.0 t ADT: 29
FM
GoodOver: BLACKHAWK CREEK BRANCH
087171002, Grundy, IA
Built 1988 Load: 37.2 t ADT: 128
LOCAL
GoodOver: FK OF BEAVER CREEK
089171103, Grundy, IA
Built 1995 Load: 37.3 t ADT: 20
LOCAL
GoodOver: SMALL STREAM
087181002, Grundy, IA
Built 1999 Load: 37.3 t ADT: 78
US 20 WB
GoodOver: GRUNDY RD
AT JUNCTION SR D18, Grundy, IA
Built 2000 Load: 37.3 t ADT: 6,800
US 20 EB
GoodOver: GRUNDY RD
AT JUNCTION WITH SR D18, Grundy, IA
Built 2000 Load: 37.3 t ADT: 6,800
LOCAL ROAD
GoodOver: BRANCH BLACK HAWK CREEK
087181202, Grundy, IA
Built 1990 Load: 37.4 t ADT: 49
US 20
GoodOver: STREAM
2.7 MILES W OF JCT SR T55, Grundy, IA
Built 1999 Load: 37.6 t ADT: 13,500
FM
GoodOver: BLACK HAWK CREEK
088172802, Grundy, IA
Built 2010 Load: 38.1 t ADT: 20
B AVENUE
GoodOver: US 20
4.0 MILES W OF JCT SR T19, Grundy, IA
Built 2003 Load: 38.5 t ADT: 59
US 20 WB
GoodOver: SOUTH BEAVER CREEK
0.1 MILE W OF JCT SR T19, Grundy, IA
Built 2003 Load: 38.5 t ADT: 4,550
C AVE
GoodOver: BRANCH BEAVER CREEK
088180502, Grundy, IA
Built 2011 Load: 38.6 t ADT: 26
B AVENUE
GoodOver: TRIB TO BEAVER CREEK
089182002, Grundy, IA
Built 2006 Load: 38.8 t ADT: 39
WB US 20
GoodOver: LOCAL STREAM
0.1 MILES W OF JCT SR T55, Grundy, IA
Built 2000 Load: 38.8 t ADT: 6,500
US 20 WB
GoodOver: SR T19
AT JUNCTION WITH SR T19, Grundy, IA
Built 2003 Load: 38.8 t ADT: 4,550
R AVE
GoodOver: N FORK BLACK HAWK CREEK
089163602, Grundy, IA
Built 2022 Load: 38.9 t ADT: 39
LOCAL
GoodOver: BR BEAVER CREEK
088170604, Grundy, IA
Built 2001 Load: 39.0 t ADT: 97
LOCAL ROAD
GoodOver: BEAVER CREEK
089171501, Grundy, IA
Built 2003 Load: 40.0 t ADT: 33
LOCAL
GoodOver: BLACKHAWK CREEK
087160705, Grundy, IA
Built 1976 Load: 40.5 t ADT: 196
US 20 EB
GoodOver: SOUTH BEAVER CREEK
0.1 MILE W OF JCT SR T19, Grundy, IA
Built 2003 Load: 41.0 t ADT: 4,550
LINCOLN ST
GoodOver: BLACKHAWK CREEK
088173501, Grundy, IA
Built 2014 Load: 41.1 t ADT: 1,176
160TH ST
GoodOver: SOUTH FORK BEAVER CREEK
088170601, Grundy, IA
Built 2022 Load: 41.8 t ADT: 44
LOCAL
GoodOver: BLACKHAWK CREEK
087160902, Grundy, IA
Built 2002 Load: 42.5 t ADT: 29
R AVE
GoodOver: BRANCH BLACK HAWK CREEK
087161402, Grundy, IA
Built 2000 Load: 42.5 t ADT: 59
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.