US Bridges

I-5 over Terrain

Good

King County, Washington · 3.0 N JCT I-90 · Structure no. 0006303B0000000

Built
1963
62 years old
Condition
Good
inspected August 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
181 ft
2 main spans
Daily traffic
3,835
2012 count
Owner
State
State Highway Agency

About this bridge

I-5 over Terrain is a prestressed concrete stringer/multi-beam or girder 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 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 3,835 vehicles a day, roughly 5% of them trucks, projected to reach 6,412 by 2036. The structure is 181 ft (55.2 m) long and 26 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

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CarriesI-5
CrossesTerrain
Location3.0 N JCT I-90
RouteInterstate 5
CountyKing County
StateWashington
Coordinates47.63325, -122.32347
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
Deck8 Very GoodNo problems noted.
Superstructure7 GoodSome minor problems.
Substructure8 Very GoodNo problems noted.
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 rating63.9 US tons
Inventory rating38 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans2
Design loadHS 20
Structure length181 ft (55.2 m)
Longest span91 ft (27.7 m)
Deck width26 ft (7.8 m)
Roadway width21 ft (6.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic3,835 (2012)
Projected traffic6,412 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$2.1 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 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 3,835 vehicles per day (2012 count), of which roughly 5% are trucks.

How long is I-5 over Terrain?

The structure is 181 ft (55.2 m) long with a longest span of 91 ft (27.7 m) and a deck 26 ft wide.

Who owns I-5 over Terrain?

It is owned by the State Highway Agency.