US Bridges

I-5 over Terrain

Good

King County, Washington · 2.5 N JCT I-90 · Structure no. 0006800F0000000

Built
1962
63 years old
Condition
Good
inspected August 2023
Type
Box Beam or Girders - Multiple
Concrete Continuous
Length
732 ft
8 main spans
Daily traffic
13,125
2012 count
Owner
State
State Highway Agency

About this bridge

I-5 over Terrain is a concrete continuous box beam or girders - multiple carrying I-5 over Terrain in King County, Washington. It was built in 1962, so it is 63 years old, older than the Washington average of 49.8 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 13,125 vehicles a day, roughly 5% of them trucks, projected to reach 21,945 by 2036. The structure is 732 ft (223.1 m) long and 26 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

CarriesI-5
CrossesTerrain
Location2.5 N JCT I-90
RouteInterstate 5
Coordinates47.62947, -122.32778
Functional classUrban Principal Arterial - Interstate

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Last inspectionAugust 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 rating50.7 US tons
Inventory rating39.2 US tons

Structure

MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans8
Design loadHS 20
Structure length732 ft (223.1 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 traffic13,125 (2012)
Projected traffic21,945 by 2036
Trucks5%
Lanes on structure1
Traffic directionOne-way traffic
CarriesHighway
CrossesOther
Detour if closed3.1 mi (5 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$8.3 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was I-5 over Terrain built?

It was built in 1962, making it 63 years old in 2025.

What condition is I-5 over Terrain in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in August 2023.

How much traffic does I-5 over Terrain carry?

About 13,125 vehicles per day (2012 count), of which roughly 5% are trucks.

How long is I-5 over Terrain?

The structure is 732 ft (223.1 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.