County profile · official public datasets

Polk County, OR

161 public highway bridges tracked in the FHWA National Bridge Inventory: 29.2% rated Good, 64% Fair, 6.8% Poor.

161
Public bridges: 29.2%
Good condition: 6.8%
Poor condition

The verdict

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

Polk County posts a higher-than-median Poor-condition share among rated counties in the state across mid-size county bridge inventory.

28th
of 36 on Poor share: 6.8%
Poor-condition share: 161
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.

Polk County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Polk County ranks #28 of 36 Oregon counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 6.8%). Polk County, Oregon contains 161 public highway bridges. Roughly 29.2% are rated “Good,” 64% “Fair,” and 6.8% “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

161

Public highway bridges in Polk County

Good condition

29.2%

47 of 161 rated 7-9

Fair condition

64%

103 of 161 rated 5-6

Poor condition

6.8%

11 of 161 rated 4 or below

In-state Poor-share rank

#28 of 36

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

Condition distribution

Share of 161 NBI-tracked bridges by lowest applicable component rating.

Good

29.2% (47)

Fair

64% (103)

Poor

6.8% (11)

Polk County's Poor-condition bridges carry 27,371 vehicle crossings a day

That is 4.5% of the county's reported daily bridge traffic on 6.8% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 2,488 crossings a day against 3,278 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 161 of 161 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

50.3% of Polk County's bridges have passed the 50-year mark

81 of the 161 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 29.2% 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 40.1% of the county's Poor-condition bridge traffic

OR 99W (Hwy 91) over North Fork Ash Creek, built 1954, carries 10,967 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 11-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 27,371 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1910s

1
1920s

5
1930s

4
1940s

4
1950s

21
1960s

39
1970s

16
1980s

16
1990s

23
2000s

23
2010s

6
2020s

3

What this shows Construction peaked in the 1960s, when 39 of the county's bridges still in the inventory were built, which is 24.2% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1976) matches the Oregon average (1975).

How Polk County compares with Oregon's closest counties by inventory size

The 5 Oregon counties nearest Polk County in number of bridges, with their condition splits. Its 6.8% Poor share is the 5th-lowest of these 6. Its average build year of 1976 against a peer-group mean of 1977 is in line with the group.

Showing the 5 closest of 35 Oregon counties eligible for comparison.

Bridge inventory size and condition shares for Polk County and the 5 Oregon counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Union County	166	42.2%	54.2%	3.6%	1980
Polk County (this page)	161	29.2%	64%	6.8%	1976
Clatsop County	155	32.9%	63.2%	3.9%	1974
Deschutes County	152	56.6%	42.1%	1.3%	1986
Yamhill County	149	24.2%	71.1%	4.7%	1975
Wasco County	148	31.8%	60.1%	8.1%	1968

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 Oregon so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside OR (161 bridges here).

Carroll County, IN · 161 bridges
Floyd County, KY · 161 bridges
Greenup County, KY · 161 bridges
Dade County, MO · 161 bridges

Similar average build year

Nearest mean year-built outside OR (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.

All 161 Good 47 Fair 103 Poor 11

Fair-condition bridges (103)

Sort:

Polk County Bridge Snapshot

Condition distribution

Polk County's Poor-condition bridges carry 27,371 vehicle crossings a day

50.3% of Polk County's bridges have passed the 50-year mark

One structure carries 40.1% of the county's Poor-condition bridge traffic

How Polk County compares with Oregon's closest counties by inventory size

Nationwide counties with similar inventory size or average build year

Similar inventory size

Similar average build year

Fair-condition bridges (103)

BALSTON ROAD

GREENWOOD ROAD

16TH ST

PLEASANT HILL ROAD

OR 99W (Hwy 91)

ELKINS ROAD

SOCIALIST VALLEY

AIRLIE ROAD

GREENWOOD ROAD

HARMONY ROAD

OR 223 (Hwy 191)

Hwy 194

FIRE HALL ROAD

OR 18 (Hwy 39)

OR 18 (Hwy 39)

OR 18 (Hwy 39)

PERRYDALE ROAD

SAVAGE ROAD

OR 99W (HWY 91)

HELMICK ROAD

OR 221 (HWY 150)

Fort Hill Road

OAK KNOLL ROAD

GUN CLUB ROAD

BUENA VISTA RD

STARR ROAD

GRAND RONDE ROAD

GOLD CREEK ROAD

GARDNER ROAD

GOOSENECK ROAD

MORROW ROAD

GOOSENECK ROAD

SMITH ROAD

GOLD CREEK ROAD

MILL CR RD

BROWN ROAD

WIGRICH ROAD

DE ARMOND ROAD

FALLS CITY ROAD

STARR ROAD

VAN WELL ROAD

OR 51 (Hwy 193)

BROWN ROAD

GAGE ROAD

OR 51 (Hwy 43)

Hwy 30

Hanna Road

VAN WELL ROAD

HART ROAD

PARKER ROAD

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