US Bridges

I-5 Nbcd over SR 104

Fair

King County, Washington · 3.1 N JCT SR 523 · Structure no. 0007071C0000000

Built
1963
62 years old, rebuilt 1995
Condition
Fair
inspected June 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
206 ft
3 main spans
Daily traffic
7,260
2023 count
Owner
State
State Highway Agency

About this bridge

I-5 Nbcd over SR 104 is a prestressed concrete stringer/multi-beam or girder carrying I-5 Nbcd over SR 104 in King County, Washington. It was built in 1963 and reconstructed in 1995, 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.

It carries about 7,260 vehicles a day, roughly 5% of them trucks, projected to reach 10,835 by 2039. The structure is 206 ft (62.8 m) long and 45 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesI-5 Nbcd
CrossesSR 104
Location3.1 N JCT SR 523
RouteInterstate 5
CountyKing County
StateWashington
Coordinates47.77736, -122.3175
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.
Substructure7 GoodSome minor problems.
Last inspectionJune 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating74 US tons
Inventory rating44 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length206 ft (62.8 m)
Longest span108 ft (32.9 m)
Deck width45 ft (13.7 m)
Roadway width42 ft (12.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic7,260 (2023)
Projected traffic10,835 by 2039
Trucks5%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
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 statusHistorical significance not determinable at this time
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$4.3 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was I-5 Nbcd over SR 104 built?

It was built in 1963, making it 62 years old in 2025. It was reconstructed in 1995.

What condition is I-5 Nbcd over SR 104 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 June 2023.

How much traffic does I-5 Nbcd over SR 104 carry?

About 7,260 vehicles per day (2023 count), of which roughly 5% are trucks.

How long is I-5 Nbcd over SR 104?

The structure is 206 ft (62.8 m) long with a longest span of 108 ft (32.9 m) and a deck 45 ft wide.

Who owns I-5 Nbcd over SR 104?

It is owned by the State Highway Agency.