US Bridges

SR 4 over Terrain Flood Plain

Fair

Wahkiakum County, Washington · 14.6 E JCT SR 401 · Structure no. 0002331B0000000

Built
1938
87 years old
Condition
Fair
inspected August 2023
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
155 ft
9 main spans
Daily traffic
1,152
2023 count
Owner
State
State Highway Agency

About this bridge

SR 4 over Terrain Flood Plain is a wood or timber stringer/multi-beam or girder carrying SR 4 over Terrain Flood Plain in Wahkiakum County, Washington. It was built in 1938, so it is 87 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 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 1,152 vehicles a day, roughly 11% of them trucks, projected to reach 1,452 by 2039. The structure is 155 ft (47.2 m) long and 31 ft wide. If it were closed, the detour would be 98.8 mi (159 km).

Location

Open in Google Maps
CarriesSR 4
CrossesTerrain Flood Plain
Location14.6 E JCT SR 401
RouteState Highway 4
CountyWahkiakum County
StateWashington
Coordinates46.35873, -123.56553
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.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating45 US tons
Inventory rating32 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckConcrete, cast-in-place
Main spans9
Design loadH 15
Structure length155 ft (47.2 m)
Longest span17 ft (5.2 m)
Deck width31 ft (9.3 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,152 (2023)
Projected traffic1,452 by 2039
Trucks11%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed98.8 mi (159 km)
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$2 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SR 4 over Terrain Flood Plain built?

It was built in 1938, making it 87 years old in 2025.

What condition is SR 4 over Terrain Flood Plain 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 August 2023.

How much traffic does SR 4 over Terrain Flood Plain carry?

About 1,152 vehicles per day (2023 count), of which roughly 11% are trucks.

How long is SR 4 over Terrain Flood Plain?

The structure is 155 ft (47.2 m) long with a longest span of 17 ft (5.2 m) and a deck 31 ft wide.

Who owns SR 4 over Terrain Flood Plain?

It is owned by the State Highway Agency.