US Bridges

I-5 over Coweeman River

Fair

Cowlitz County, Washington · 1.4 N JCT SR 432 · Structure no. 0010750A0000000

Built
1979
46 years old
Condition
Fair
inspected April 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete Continuous
Length
464 ft
4 main spans
Daily traffic
28,940
2023 count
Owner
State
State Highway Agency

About this bridge

I-5 over Coweeman River is a prestressed concrete continuous stringer/multi-beam or girder carrying I-5 over Coweeman River in Cowlitz County, Washington. It was built in 1979, so it is 46 years old, younger 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 28,940 vehicles a day, roughly 21% of them trucks, projected to reach 38,572 by 2039. The structure is 464 ft (141.4 m) long and 55 ft wide. If it were closed, the detour would be 6.8 mi (11 km).

Location

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CarriesI-5
CrossesCoweeman River
Location1.4 N JCT SR 432
RouteInterstate 5
CountyCowlitz County
StateWashington
Coordinates46.12489, -122.89204
Functional classUrban Principal Arterial - Interstate

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection7 GoodSome minor problems.
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 geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating39.7 US tons
Inventory rating30.3 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20 + Mod
Structure length464 ft (141.4 m)
Longest span146 ft (44.5 m)
Deck width55 ft (16.8 m)
Roadway width52 ft (15.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic28,940 (2023)
Projected traffic38,572 by 2039
Trucks21%
Lanes on structure3
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.8 mi (11 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

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$11.9 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was I-5 over Coweeman River built?

It was built in 1979, making it 46 years old in 2025.

What condition is I-5 over Coweeman 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 April 2024.

How much traffic does I-5 over Coweeman River carry?

About 28,940 vehicles per day (2023 count), of which roughly 21% are trucks.

How long is I-5 over Coweeman River?

The structure is 464 ft (141.4 m) long with a longest span of 146 ft (44.5 m) and a deck 55 ft wide.

Who owns I-5 over Coweeman River?

It is owned by the State Highway Agency.