County profile · official public datasets

Dallas County, IA

199 public highway bridges tracked in the FHWA National Bridge Inventory: 44.7% rated Good, 46.2% Fair, 9% Poor.

199
Public bridges
44.7%
Good condition
9%
Poor condition

The verdict

According to the Federal Highway Administration's 2024 National Bridge Inventory.

Dallas County posts a top-quartile lowest Poor-condition share among rated counties in the state across mid-size county bridge inventory.

Top 15%
lowest Poor share in state
9%
Poor-condition share
199
public highway bridges
1978
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.

Dallas County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Dallas County ranks #15 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 9%). Dallas County, Iowa contains 199 public highway bridges. Roughly 44.7% are rated “Good,” 46.2% “Fair,” and 9% “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.

Total bridges

199

Public highway bridges in Dallas County

Good condition

44.7%

89 of 199 rated 7-9

Fair condition

46.2%

92 of 199 rated 5-6

Poor condition

9%

18 of 199 rated 4 or below

In-state Poor-share rank

#15 of 99

Among Iowa counties with 5+ bridges, lower share ranks better

Condition distribution

Share of 199 NBI-tracked bridges by lowest applicable component rating.

Good
44.7% (89)
Fair
46.2% (92)
Poor
9% (18)

Dallas County's Poor-condition bridges carry 11,710 vehicle crossings a day

That is 2.1% of the county's reported daily bridge traffic on 9.1% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 651 crossings a day against 1,779 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 198 of 199 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

42.2% of Dallas County's bridges have passed the 50-year mark

84 of the 199 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 44.7% 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 22.4% of the county's Poor-condition bridge traffic

FM over JOHNSON CREEK, built 1933, carries 2,628 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 18-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 11,710 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

When Dallas County's bridges were built

199 bridges with a recorded construction year, grouped by decade

bridges

What this shows Construction peaked in the 1960s, when 31 of the county's bridges still in the inventory were built, which is 15.6% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1978) matches the Iowa average (1979).

Source FHWA National Bridge Inventory (year built) As of 2024 NBI release

How Dallas County compares with Iowa's closest counties by inventory size

The 5 Iowa counties nearest Dallas County in number of bridges, with their condition splits. Its 9% Poor share is the 1st-lowest of these 6. Its average build year of 1978 against a peer-group mean of 1973 is 5 years newer.

Showing the 5 closest of 98 Iowa counties eligible for comparison.

Bridge inventory size and condition shares for Dallas County and the 5 Iowa counties closest to it in inventory size
County Bridges Poor
Pocahontas County 201 25.4%
Dallas County (this page) 199 9%
Allamakee County 197 9.1%
Calhoun County 197 25.4%
Decatur County 197 40.6%
Page County 196 32.1%

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 Dallas 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 Dallas County, both outside Iowa so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside IA (199 bridges here).

Similar average build year

Nearest mean year-built outside IA (1978 here).

Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.

All 199 Good 89 Fair 92 Poor 18

Good-condition bridges (89)

EB IA 141

Good

Over: LITTLE BEAVER CREEK

2.2 MILES W OF JCT IA 210, Dallas, IA

Built 1997 Load: 32.7 t ADT: 4,300

WATERFORD RD WB

Good

Over: WALNUT CREEK

P40000350, Dallas, IA

Built 2007 Load: 33.2 t ADT: 266

FM

Good

Over: BEAVER CREEK

081271604, Dallas, IA

Built 1986 Load: 33.5 t ADT: 20

BOONEVILLE RD

Good

Over: SUGAR CREEK

City of West Des Moines, Dallas, IA

Built 2018 Load: 33.7 t ADT: 70

A AVE

Good

Over: BRANCH MOSQUITO CREEK

079290602, Dallas, IA

Built 2015 Load: 34.3 t ADT: 15

F90 RACCOON RVR DR

Good

Over: DRAINAGE DITCH

Dallas County, Dallas, IA

Built 2018 Load: 34.7 t ADT: 2,007

LOCAL

Good

Over: S RACCOON RIVER

078290327, Dallas, IA

Built 1996 Load: 34.9 t ADT: 82

FM

Good

Over: SO RACOON RIVER

078290706, Dallas, IA

Built 2003 Load: 34.9 t ADT: 767

STATE ST

Good

Over: OXLEY CREEK

0802612, Dallas, IA

Built 2016 Load: 36.0 t ADT: 1,379

S GRAND PRAIRIE

Good

Over: RACCOON RIVER

West Des Moines, Dallas, IA

Built 2018 Load: 36.3 t ADT: 5

LOCAL

Good

Over: PANTHER CREEK

078281603, Dallas, IA

Built 1989 Load: 36.9 t ADT: 110

COUNTY ROAD

Good

Over: WALNUT CREEK

079261502, Dallas, IA

Built 1988 Load: 37.1 t ADT: 51

LOCAL

Good

Over: BEAVER CREEK

081270702, Dallas, IA

Built 2004 Load: 37.2 t ADT: 103

JORDAN CREEK PKWY

Good

Over: I-80

1.6 mi. W of W Jct. I-35, Dallas, IA

Built 2001 Load: 37.9 t ADT: 10,600

COUNTY ROAD

Good

Over: BEAVER CREEK

081272301, Dallas, IA

Built 2005 Load: 38.2 t ADT: 26

WILLIS AVE

Good

Over: FROG CREEK

0.2 Miles West of 1st Ave, Dallas, IA

Built 2018 Load: 38.2 t ADT: 2,269

STAGECOACH DR

Good

Over: SUGAR CREEK

City of West Des Moines, Dallas, IA

Built 2017 Load: 38.2 t ADT: 143

GRAND AVE

Good

Over: ROLLING HILLS CREEK

.5 Mi. W. of S JC Pkwy, Dallas, IA

Built 2019 Load: 39.2 t ADT: 96

EB IA 141

Good

Over: BEAVER CREEK

1.3 MI. E OF JCT. US 169, Dallas, IA

Built 1997 Load: 39.2 t ADT: 4,300

220TH ST

Good

Over: MOSQUITO CREEK

080292901, Dallas, IA

Built 1991 Load: 39.6 t ADT: 41

JEWEL CIR

Good

Over: BEAR CREEK

00000, Dallas, IA

Built 2011 Load: 40.2 t ADT: 110

FILMORE CT

Good

Over: BEAR CREEK

078292704, Dallas, IA

Built 2015 Load: 41.1 t ADT: 91

360TH STREET

Good

Over: JOHNSON CREEK

RRD over Johnson Creek, Dallas, IA

Built 2022 Load: 41.1 t ADT: 2,628

D AVE

Good

Over: MOSQUITO CREEK

079291502, Dallas, IA

Built 2013 Load: 41.5 t ADT: 26

LOCAL

Good

Over: BEAVER CREEK

080261304, Dallas, IA

Built 1982 Load: 43.7 t ADT: 154

GRAND PRAIRIE PKWY

Good

Over: SUGAR CREEK

GPPW over Sugar Creek, Dallas, IA

Built 2016 Load: 44.4 t ADT: 5,474

BOONEVILLE RD

Good

Over: JOHNSON CREEK

Booneville Rd over JCreek, Dallas, IA

Built 2022 Load: 44.4 t ADT: 66

GRAND AVE

Good

Over: JOHNSON CREEK

Grand Ave o JohnsonCreek, Dallas, IA

Built 2023 Load: 45.0 t ADT: 289

COUNTRY ROAD

Good

Over: BEAVER CREEK

081272001, Dallas, IA

Built 2003 Load: 45.4 t ADT: 26

LOCAL

Good

Over: MERCER CREEK

078281203, Dallas, IA

Built 1974 Load: 46.3 t ADT: 62

LOCAL

Good

Over: SLOUGH CREEK

081272801, Dallas, IA

Built 2003 Load: 48.2 t ADT: 30

COUNTY ROAD

Good

Over: BEAVER CREEK

081272304, Dallas, IA

Built 2001 Load: 48.5 t ADT: 51

156TH ST

Good

Over: LITTLE WALNUT CREEK

P55000600, Dallas, IA

Built 2007 Load: 49.3 t ADT: 1,257

156TH ST

Good

Over: LITTLE WALNUT CREEK

P55000600, Dallas, IA

Built 2007 Load: 49.3 t ADT: 1,211

FM

Good

Over: SOUTH RACCOON RIVER

078290210, Dallas, IA

Built 1981 Load: 51.2 t ADT: 170

FM

Good

Over: BULGER CREEK

078272903, Dallas, IA

Built 1995 Load: 52.9 t ADT: 150

COUNTY ROAD

Good

Over: MOSQUITO CREEK

079290806, Dallas, IA

Built 2002 Load: 52.9 t ADT: 51

I-80

Good

Over: BEAR CREEK

1.1 mi. W of Jct. SR P-57, Dallas, IA

Built 1965 Load: 90.5 t ADT: 29,500

I-80

Good

Over: PANTHER CREEK

0.6 mi. W of SR P58 & F90, Dallas, IA

Built 1965 Load: 99.9 t ADT: 32,100

Read our methodology - how this data is sourced, computed, and verified.

Related

Browse all → | Rankings →
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.