County profile · official public datasets

Clackamas County, OR

367 public highway bridges tracked in the FHWA National Bridge Inventory: 31.1% rated Good, 66.5% Fair, 2.5% Poor.

367
Public bridges: 31.1%
Good condition: 2.5%
Poor condition

The verdict

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

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

Top 28%
lowest Poor share in state: 2.5%
Poor-condition share: 367
public highway bridges: 1975
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.

Clackamas County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Clackamas County ranks #10 of 36 Oregon counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 2.5%). Clackamas County, Oregon contains 367 public highway bridges. Roughly 31.1% are rated “Good,” 66.5% “Fair,” and 2.5% “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

367

Public highway bridges in Clackamas County

Good condition

31.1%

114 of 367 rated 7-9

Fair condition

66.5%

244 of 367 rated 5-6

Poor condition

2.5%

9 of 367 rated 4 or below

In-state Poor-share rank

#10 of 36

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

Condition distribution

Share of 367 NBI-tracked bridges by lowest applicable component rating.

Good

31.1% (114)

Fair

66.5% (244)

Poor

2.5% (9)

Clackamas County's Poor-condition bridges carry 35,357 vehicle crossings a day

That is 0.7% of the county's reported daily bridge traffic on 2.5% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 3,929 crossings a day against 6,104 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 367 of 367 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

61.9% of Clackamas County's bridges have passed the 50-year mark

227 of the 367 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 31.1% 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 50.7% of the county's Poor-condition bridge traffic

OR 99E (Hwy 81) over Partial Viaduct, built 1940, carries 17,911 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 9-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 35,357 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1920s

8
1930s

19
1940s

9
1950s

59
1960s

72
1970s

77
1980s

22
1990s

16
2000s

54
2010s

24
2020s

7

What this shows Construction peaked in the 1970s, when 77 of the county's bridges still in the inventory were built, which is 21% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1975) matches the Oregon average (1975).

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

The 5 Oregon counties nearest Clackamas County in number of bridges, with their condition splits. Its 2.5% Poor share is the 2nd-lowest of these 6. Its average build year of 1975 against a peer-group mean of 1974 is in line with the group.

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

Bridge inventory size and condition shares for Clackamas County and the 5 Oregon counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Multnomah County	473	11.8%	85.2%	3%	1967
Jackson County	401	34.2%	64.3%	1.5%	1976
Marion County	373	21.2%	74.5%	4.3%	1971
Clackamas County (this page)	367	31.1%	66.5%	2.5%	1975
Washington County	326	35.6%	62%	2.5%	1983
Umatilla County	321	31.5%	64.5%	4%	1973

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

Similar inventory size

Nearest county inventories outside OR (367 bridges here).

Allen County, OH · 367 bridges
Centre County, PA · 367 bridges
Schuylkill County, PA · 368 bridges
Sullivan County, TN · 368 bridges

Similar average build year

Nearest mean year-built outside OR (1975 here).

San Bernardino County, CA · avg 1975 · 1,422 bridges
Fulton County, GA · avg 1975 · 775 bridges
Westmoreland County, PA · avg 1975 · 620 bridges
Monroe County, NY · avg 1975 · 615 bridges

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

All 367 Good 114 Fair 244 Poor 9

All bridges (367)

Sort:

Clackamas County Bridge Snapshot

Condition distribution

Clackamas County's Poor-condition bridges carry 35,357 vehicle crossings a day

61.9% of Clackamas County's bridges have passed the 50-year mark

One structure carries 50.7% of the county's Poor-condition bridge traffic

How Clackamas 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

All bridges (367)

NO DATA ENTERED

TEN EYCK RD

MILLPORT SLOUGH RD

Kleinsmith Road

ROAD

Wilsonville Road

BONNEY RD. (3)

ROAD

HWY 171 (OR 224)

ROAD

ROAD

ROAD

ROAD

ROAD

RUSK ROAD (N)

07 S 04 E 29.01:

ROAD

Mattoon Road

ROAD

ROAD

CHILDS RD

ROAD

US 26 (HWY 026)

07 S 04 E 01.01:

DHOOGE ROAD (N)

Hwy 161

422ND AVE

LOLO PASS RD

ROAD

06 S 04 E 06.00:

SOUTH SHORE BLVD

STAFFORD RD

FOSTER RD

ROAD

ROAD

Hwy 026

07 S 03 E 14.02:

Road

SUNNYBROOK ST (W)

GRAVES ROAD

GRAHAMS FERRY ROAD

FERNWOOD RD

Arrowhead Crk Ln

BEAVER CREEK RD

WHISKEY HILL RD

ROAD

SPRINGWATER RD

WASHINGTON ST

EAST BRIDGE ST

PORTER RD

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