US Bridges

I-5 over Terrain

FairPosted for load

King County, Washington · 2.4 N JCT I-90 · Structure no. 0006800B0000000

Built
1963
62 years old
Condition
Fair
inspected July 2023
Type
Tee Beam
Concrete Continuous
Length
381 ft
11 main spans
Daily traffic
91,632
2023 count
Owner
State
State Highway Agency

About this bridge

I-5 over Terrain is a concrete continuous tee beam carrying I-5 over Terrain in King County, Washington. It was built in 1963, so it is 62 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. Its operating status is: posted for load restriction.

It carries about 91,632 vehicles a day, roughly 5% of them trucks, projected to reach 133,212 by 2039. The structure is 381 ft (116.1 m) long and 33 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

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CarriesI-5
CrossesTerrain
Location2.4 N JCT I-90
RouteInterstate 5
CountyKing County
StateWashington
Coordinates47.62642, -122.32817
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourBridge not over waterway
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating33.6 US tons
Inventory rating25.7 US tons

Structure

Structure typeTee Beam
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans11
Design loadHS 20
Structure length381 ft (116.1 m)
Longest span38 ft (11.6 m)
Deck width33 ft (10.1 m)
Roadway width66 ft (20.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic91,632 (2023)
Projected traffic133,212 by 2039
Trucks5%
Lanes on structure4
Traffic directionOne-way traffic
CarriesHighway
CrossesOther
Detour if closed3.1 mi (5 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$12.3 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was I-5 over Terrain built?

It was built in 1963, making it 62 years old in 2025.

What condition is I-5 over Terrain 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 July 2023.

How much traffic does I-5 over Terrain carry?

About 91,632 vehicles per day (2023 count), of which roughly 5% are trucks.

How long is I-5 over Terrain?

The structure is 381 ft (116.1 m) long with a longest span of 38 ft (11.6 m) and a deck 33 ft wide.

Who owns I-5 over Terrain?

It is owned by the State Highway Agency.