US Bridges

US101 (hwy 9) over Necanicum River

Fair

Clatsop County, Oregon · 022 MI S Seaside S C Lmts · Structure no. 01481 009 02410

Built
1930
95 years old
Condition
Fair
inspected October 2023
Type
Tee Beam
Concrete Continuous
Length
172 ft
3 main spans
Daily traffic
14,464
2022 count
Owner
State
State Highway Agency

About this bridge

US101 (hwy 9) over Necanicum River is a concrete continuous tee beam carrying US101 (hwy 9) over Necanicum River in Clatsop County, Oregon. It was built in 1930, so it is 95 years old, older than the Oregon average of 49.9 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 6 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

It carries about 14,464 vehicles a day, roughly 3% of them trucks, projected to reach 14,600 by 2042. The structure is 172 ft (52.4 m) long and 30 ft wide. If it were closed, the detour would be 32.3 mi (52 km).

Location

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CarriesUS101 (hwy 9)
CrossesNecanicum River
Location022 MI S Seaside S C Lmts
RouteU.S. Route 101
CountyClatsop County
StateOregon
Coordinates45.95292, -123.92655
Functional classRural Principal Arterial - Other

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionOctober 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating34 US tons
Inventory rating26.1 US tons

Structure

Structure typeTee Beam
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadH 15
Structure length172 ft (52.4 m)
Longest span68 ft (20.7 m)
Deck width30 ft (9.2 m)
Roadway width27 ft (8.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic14,464 (2022)
Projected traffic14,600 by 2042
Trucks3%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed32.3 mi (52 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkNon-Interstate STRAHNET route

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedWidening of existing bridge without deck rehabilitation
Estimated improvement cost$881,000
NavigationNo navigation control on waterway

Frequently asked questions

When was US101 (hwy 9) over Necanicum River built?

It was built in 1930, making it 95 years old in 2025.

What condition is US101 (hwy 9) over Necanicum River in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in October 2023.

How much traffic does US101 (hwy 9) over Necanicum River carry?

About 14,464 vehicles per day (2022 count), of which roughly 3% are trucks.

How long is US101 (hwy 9) over Necanicum River?

The structure is 172 ft (52.4 m) long with a longest span of 68 ft (20.7 m) and a deck 30 ft wide.

Who owns US101 (hwy 9) over Necanicum River?

It is owned by the State Highway Agency.