US Bridges

US101 (hwy 9) over Wilson River Slough

Fair

Tillamook County, Oregon · 014 MI N Tillamook · Structure no. 01498 009 06414

Built
1931
94 years old
Condition
Fair
inspected March 2024
Type
Tee Beam
Concrete Continuous
Length
120 ft
3 main spans
Daily traffic
11,881
2022 count
Owner
State
State Highway Agency

About this bridge

US101 (hwy 9) over Wilson River Slough is a concrete continuous tee beam carrying US101 (hwy 9) over Wilson River Slough in Tillamook County, Oregon. It was built in 1931, so it is 94 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 11,881 vehicles a day, roughly 4% of them trucks, projected to reach 12,400 by 2042. The structure is 120 ft (36.6 m) long and 36 ft wide. If it were closed, the detour would be 55.9 mi (90 km).

Location

Open in Google Maps
CarriesUS101 (hwy 9)
CrossesWilson River Slough
Location014 MI N Tillamook
RouteU.S. Route 101
CountyTillamook County
StateOregon
Coordinates45.47955, -123.84467
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.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionMarch 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
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 rating29.3 US tons
Inventory rating22.5 US tons

Structure

Structure typeTee Beam
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadH 15
Structure length120 ft (36.6 m)
Longest span46 ft (14 m)
Deck width36 ft (11.1 m)
Roadway width27 ft (8.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic11,881 (2022)
Projected traffic12,400 by 2042
Trucks4%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed55.9 mi (90 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$615,000
NavigationNo navigation control on waterway

Frequently asked questions

When was US101 (hwy 9) over Wilson River Slough built?

It was built in 1931, making it 94 years old in 2025.

What condition is US101 (hwy 9) over Wilson River Slough 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 March 2024.

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

About 11,881 vehicles per day (2022 count), of which roughly 4% are trucks.

How long is US101 (hwy 9) over Wilson River Slough?

The structure is 120 ft (36.6 m) long with a longest span of 46 ft (14 m) and a deck 36 ft wide.

Who owns US101 (hwy 9) over Wilson River Slough?

It is owned by the State Highway Agency.