Total bridges
545
Public highway bridges in Polk County
County profile · official public datasets
Polk County, IA
545 public highway bridges tracked in the FHWA National Bridge Inventory: 57.8% rated Good, 35.8% Fair, 6.4% Poor.
- 545
- Public bridges
- 57.8%
- Good condition
- 6.4%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Polk County pairs a top-10% lowest Poor-condition share among rated counties in the state with a newer average build year than the state inventory.
- Top 7%
- lowest Poor share in state
- 6.4%
- Poor-condition share
- 545
- public highway bridges
- 1986
- 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.
Polk County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Polk County ranks #7 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 6.4%). Polk County, Iowa contains 545 public highway bridges. Roughly 57.8% are rated “Good,” 35.8% “Fair,” and 6.4% “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
57.8%
315 of 545 rated 7-9
Fair condition
35.8%
195 of 545 rated 5-6
Poor condition
6.4%
35 of 545 rated 4 or below
In-state Poor-share rank
#7 of 99
Among Iowa counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 545 NBI-tracked bridges by lowest applicable component rating.
Good 57.8% (315)
Fair 35.8% (195)
Poor 6.4% (35)
Polk County's Poor-condition bridges carry 81,796 vehicle crossings a day
That is 1.2% of the county's reported daily bridge traffic on 6.3% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 2,406 crossings a day against 11,988 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 542 of 545 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
29.9% of Polk County's bridges have passed the 50-year mark
163 of the 545 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 57.8% 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 19.1% of the county's Poor-condition bridge traffic
FLEUR DR over OLD UP RR & SW 22ND, built 1936, carries 15,634 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 35-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 81,796 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Polk County's bridges were built
545 bridges with a recorded construction year, grouped by decade
- 1900s 4
1900–1909
4 bridges
- 1910s 8
1910–1919
8 bridges
- 1920s 9
1920–1929
9 bridges
- 1930s 14
1930–1939
14 bridges
- 1940s 5
1940–1949
5 bridges
- 1950s 43
1950–1959
43 bridges
- 1960s
1960–1969
58 bridges
- 1970s 44
1970–1979
44 bridges
- 1980s 39
1980–1989
39 bridges
- 1990s
1990–1999
103 bridges
- 2000s
2000–2009
142 bridges
- 2010s
2010–2019
64 bridges
- 2020s 12
2020–2029
12 bridges
What this shows Construction peaked in the 2000s, when 142 of the county's bridges still in the inventory were built, which is 26.1% of those with a recorded year. That cohort is now 15 to 24 years old in the 2024 inventory. Its average build year is 1986, 7 years newer than the Iowa average of 1979.
How Polk County compares with Iowa's closest counties by inventory size
The 5 Iowa counties nearest Polk County in number of bridges, with their condition splits. Its 6.4% Poor share is the 3rd-lowest of these 6. Its average build year of 1986 against a peer-group mean of 1984 is in line with the group.
Showing the 5 closest of 98 Iowa counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Pottawattamie County | 557 | 38.8% | 51.9% | 9.3% | 1981 |
| Polk County (this page) | 545 | 57.8% | 35.8% | 6.4% | 1986 |
| Linn County | 506 | 46.4% | 47.2% | 6.3% | 1987 |
| Black Hawk County | 489 | 52.8% | 40.7% | 6.5% | 1983 |
| Woodbury County | 455 | 39.3% | 39.6% | 21.1% | 1985 |
| Sioux County | 449 | 62.4% | 34.7% | 2.9% | 1982 |
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 Polk 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 Polk County, both outside Iowa so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside IA (545 bridges here).
- Grafton County, NH · 544 bridges
- Yavapai County, AZ · 543 bridges
- East Baton Rouge County, LA · 548 bridges
- Kanawha County, WV · 554 bridges
Similar average build year
Nearest mean year-built outside IA (1986 here).
- El Paso County, TX · avg 1986 · 783 bridges
- Caddo County, LA · avg 1986 · 682 bridges
- Weld County, CO · avg 1986 · 614 bridges
- Canadian County, OK · avg 1986 · 493 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Fair-condition bridges (195)
WB I-235
FairOver: WALNUT CREEK
3.4 MI E OF W JCT 35/80, Polk, IA
Built 1968 Load: 39.2 t ADT: 58,050
WB I-235
FairOver: 22ND ST
2.1 MI E OF W JCT I-35/80, Polk, IA
Built 1968 Load: 39.3 t ADT: 48,250
MEREDITH DR
FairOver: N WALNUT CREEK
O39400540, Polk, IA
Built 1989 Load: 39.3 t ADT: 12,150
IA 163
FairOver: FOUR MILE CREEK
1.7 mi. W of Jct. U.S. 65, Polk, IA
Built 1975 Load: 39.4 t ADT: 23,300
SB I35 WB I80
FairOver: NS RR & IA 141
AT JCT. IOWA 141, Polk, IA
Built 1958 Load: 39.4 t ADT: 35,200
SCOTT AVE
FairOver: DES MOINES RIVER
078241000, Polk, IA
Built 1937 Load: 39.5 t ADT: 4,166
LOCAL NE 54TH
FairOver: FOUR MILE CREEK
080240100, Polk, IA
Built 1990 Load: 39.5 t ADT: 1,377
SB I-35 WB I-80
FairOver: DRAINAGE DITCH
0.8 mi. W of Jct. IA 415, Polk, IA
Built 1958 Load: 40.0 t ADT: 48,000
CORP WOODS DR
FairOver: I-35
1.9 mi. N of E Jct. I-80, Polk, IA
Built 2003 Load: 40.1 t ADT: 12,903
I 80 EB
FairOver: I-35
AT W JCT. I-35, Polk, IA
Built 1966 Load: 40.8 t ADT: 15,200
SB I-35
FairOver: RACCOON RIVER
0.6 mi. N of Jct. Iowa #5, Polk, IA
Built 2003 Load: 41.1 t ADT: 28,800
FAIRVIEW DR
FairOver: FOUR MILE CREEK
078230500, Polk, IA
Built 1980 Load: 41.9 t ADT: 1,651
LOCAL
FairOver: SPRING CREEK
078220705, Polk, IA
Built 1975 Load: 42.1 t ADT: 597
IA 160
FairOver: I-35
AT JUNCTION INTERSTATE 35, Polk, IA
Built 1986 Load: 42.3 t ADT: 22,700
EB I-235
FairOver: CUMMINS PARKWAY
0.2 MILE E OF JCT IA 28, Polk, IA
Built 1967 Load: 42.3 t ADT: 51,400
WB I-235
FairOver: CUMMINS PARKWAY
0.2 MILE E OF JCT IA 28, Polk, IA
Built 1967 Load: 42.3 t ADT: 51,400
EB I-235
FairOver: 17TH ST
1.3 mi. W of Jct. IA 28, Polk, IA
Built 1967 Load: 42.4 t ADT: 56,600
SW 42ND ST
FairOver: FRINK CREEK
078243000, Polk, IA
Built 1976 Load: 42.4 t ADT: 121
WB/NB IA 141
FairOver: IA 44
AT JUNCTION IOWA 44, Polk, IA
Built 1974 Load: 42.8 t ADT: 9,200
FM NE 46TH ST
FairOver: MUCHIKINOCK CREEK
080233402, Polk, IA
Built 1990 Load: 43.4 t ADT: 270
EB/SB IA 141
FairOver: IA 44
AT JUNCTION IOWA 44, Polk, IA
Built 1974 Load: 43.9 t ADT: 9,200
EB I-235
FairOver: NE 46 AVE
0.5 MILE S OF I-35/80 JCT, Polk, IA
Built 1967 Load: 44.1 t ADT: 36,450
BIRDLAND DRIVE
FairOver: BIRDLAND LAGOON
079243583, Polk, IA
Built 1930 Load: 44.3 t ADT: 351
WB IA 163
FairOver: MUD CREEK
2.3 MILES W OF JCT IA 316, Polk, IA
Built 1963 Load: 44.8 t ADT: 7,450
UNIV AVE
FairOver: KEOSAUQUA
078240500, Polk, IA
Built 1987 Load: 45.0 t ADT: 13,517
SB I-35 WB I-80
FairOver: DRAINAGE
0.2 mi. E Jct. US 69, Polk, IA
Built 2000 Load: 45.8 t ADT: 41,550
FM NE 46TH ST
FairOver: MUCHIKINOCK CREEK
080233402, Polk, IA
Built 1990 Load: 45.9 t ADT: 270
BUFFALO RD
FairOver: WALNUT CREEK
078250300, Polk, IA
Built 1991 Load: 47.1 t ADT: 727
FM
FairOver: SPRING CREEK
078232407, Polk, IA
Built 1978 Load: 47.2 t ADT: 649
FM
FairOver: TRIB. TO BIG CREEK
081250901, Polk, IA
Built 1991 Load: 49.2 t ADT: 150
EP TRUE PARKWAY
FairOver: JORDON CREEK
P27050490, Polk, IA
Built 1990 Load: 49.2 t ADT: 11,432
NB I35 EB I80
FairOver: NS RR & IA 141
At the Jct. IA 141, Polk, IA
Built 1958 Load: 49.9 t ADT: 35,200
FOREST AVE
FairOver: CLOSES CREEK
000000000, Polk, IA
Built 1900 Load: 50.2 t ADT: 2,608
NB RAMP TO UNIV
FairOver: RAMP H
1.0 MILE E OF W JCT I-35, Polk, IA
Built 1984 Load: 50.4 t ADT: 3,440
E ARMY POST RD
FairOver: SMALL NATURAL STREAM
078233100, Polk, IA
Built 1952 Load: 50.7 t ADT: 7,065
SE 14TH ST
FairOver: CREEK
078243502, Polk, IA
Built 1980 Load: 50.9 t ADT: 576
US 6
FairOver: N WALNUT CREEK&BIKE PATH
1.1 MI W OF W JCT IA 28, Polk, IA
Built 1969 Load: 51.1 t ADT: 20,100
FM
FairOver: WHITE OAK CREEK
081231603, Polk, IA
Built 1990 Load: 51.2 t ADT: 270
SCOTT AVE
FairOver: FOUR MILE CREEK
F20610970, Polk, IA
Built 1993 Load: 51.9 t ADT: 2,694
E DOUGLAS AVE
FairOver: FOUR MILE CREEK
000000000, Polk, IA
Built 1999 Load: 52.2 t ADT: 820
HUBBELL AVE
FairOver: FOUR MILE CREEK
079232901, Polk, IA
Built 2002 Load: 53.8 t ADT: 8,411
S UNION
FairOver: YEADER CREEK
078242700, Polk, IA
Built 1976 Load: 56.4 t ADT: 4,106
NE 46TH ST
FairOver: MUCHIKINOCK CREEK
080233402, Polk, IA
Built 1990 Load: 65.6 t ADT: 270
EB I-235
FairOver: GUTHRIE AVE
1.2 MILES E OF JCT IA 163, Polk, IA
Built 2006 Load: 74.5 t ADT: 33,900
E HARTFORD AVE
FairOver: CREEK
078241100, Polk, IA
Built 1980 Load: 88.9 t ADT: 5,181
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.