US Bridges

SR 4 over Skamokawa Creek

Fair

Wahkiakum County, Washington · 24.2 E JCT SR 401 · Structure no. 0002457A0000000

Built
1939
86 years old
Condition
Fair
inspected April 2024
Type
Girder and Floorbeam System
Steel
Length
239 ft
2 main spans
Daily traffic
1,573
2023 count
Owner
State
State Highway Agency

About this bridge

SR 4 over Skamokawa Creek is a steel girder and floorbeam system carrying SR 4 over Skamokawa Creek in Wahkiakum County, Washington. It was built in 1939, so it is 86 years old, older than the Washington average of 49.8 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 5 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 1,573 vehicles a day, roughly 13% of them trucks, projected to reach 1,667 by 2039. The structure is 239 ft (72.8 m) long and 25 ft wide. If it were closed, the detour would be 6.2 mi (10 km).

Location

Open in Google Maps
CarriesSR 4
CrossesSkamokawa Creek
Location24.2 E JCT SR 401
RouteState Highway 4
CountyWahkiakum County
StateWashington
Coordinates46.27039, -123.45672
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.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionApril 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 geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating44 US tons
Inventory rating26 US tons

Structure

Structure typeGirder and Floorbeam System
MaterialSteel
DeckConcrete, cast-in-place
Main spans2 (+5 approach)
Design loadH 15
Structure length239 ft (72.8 m)
Longest span93 ft (28.3 m)
Deck width25 ft (7.6 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,573 (2023)
Projected traffic1,667 by 2039
Trucks13%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed6.2 mi (10 km)
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusPossibly eligible for the National Register; requires further investigation
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$3.4 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SR 4 over Skamokawa Creek built?

It was built in 1939, making it 86 years old in 2025.

What condition is SR 4 over Skamokawa Creek 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 April 2024.

How much traffic does SR 4 over Skamokawa Creek carry?

About 1,573 vehicles per day (2023 count), of which roughly 13% are trucks.

How long is SR 4 over Skamokawa Creek?

The structure is 239 ft (72.8 m) long with a longest span of 93 ft (28.3 m) and a deck 25 ft wide.

Who owns SR 4 over Skamokawa Creek?

It is owned by the State Highway Agency.