US Bridges

I-5 over Terrain

Fair

King County, Washington · 2.1 N JCT I-90 · Structure no. 0006800H0000000

Built
1964
61 years old
Condition
Fair
inspected April 2023
Type
Slab
Concrete Continuous
Length
743 ft
21 main spans
Daily traffic
3,999
2012 count
Owner
State
State Highway Agency

About this bridge

I-5 over Terrain is a concrete continuous slab carrying I-5 over Terrain in King County, Washington. It was built in 1964, so it is 61 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 3,999 vehicles a day, roughly 1% of them trucks, projected to reach 6,686 by 2036. The structure is 743 ft (226.5 m) long and 26 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesI-5
CrossesTerrain
Location2.1 N JCT I-90
RouteInterstate 5
CountyKing County
StateWashington
Coordinates47.62953, -122.3275
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.
Substructure7 GoodSome minor problems.
Last inspectionApril 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation7: Better than present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating83 US tons
Inventory rating48.9 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans21
Design loadHS 20
Structure length743 ft (226.5 m)
Longest span104 ft (31.7 m)
Deck width26 ft (7.8 m)
Roadway width21 ft (6.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic3,999 (2012)
Projected traffic6,686 by 2036
Trucks1%
Lanes on structure1
Traffic directionOne-way traffic
CarriesHighway
CrossesOther
Detour if closed1.2 mi (2 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$9.5 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was I-5 over Terrain built?

It was built in 1964, making it 61 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 April 2023.

How much traffic does I-5 over Terrain carry?

About 3,999 vehicles per day (2012 count), of which roughly 1% are trucks.

How long is I-5 over Terrain?

The structure is 743 ft (226.5 m) long with a longest span of 104 ft (31.7 m) and a deck 26 ft wide.

Who owns I-5 over Terrain?

It is owned by the State Highway Agency.