US Bridges

Seneca ST over I-5

Fair

King County, Washington · 1.2 N JCT I-90 · Structure no. 0007110E0000000

Built
1964
61 years old
Condition
Fair
inspected August 2023
Type
Box Beam or Girders - Multiple
Concrete Continuous
Length
250 ft
3 main spans
Daily traffic
10,000
2017 count
Owner
State
State Highway Agency

About this bridge

Seneca ST over I-5 is a concrete continuous box beam or girders - multiple carrying Seneca ST over I-5 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 10,000 vehicles a day, roughly 5% of them trucks, projected to reach 15,000 by 2038. The structure is 250 ft (76.2 m) long and 62 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesSeneca ST
CrossesI-5
Location1.2 N JCT I-90
RouteCity Street 0
CountyKing County
StateWashington
Coordinates47.60872, -122.33136
Functional classUrban Minor Arterial

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 inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation7: Better than present minimum criteria
Deck geometry2: Basically intolerable, requiring high priority of replacement
Approach roadway alignment8: Equal to present desirable criteria
Operating rating90.9 US tons
Inventory rating54 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length250 ft (76.2 m)
Longest span96 ft (29.3 m)
Deck width62 ft (18.8 m)
Roadway width36 ft (11 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic10,000 (2017)
Projected traffic15,000 by 2038
Trucks5%
Lanes on structure3
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesHighway
Detour if closed1.9 mi (3 km)
TollOn a free road
National Highway SystemNo

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$5.9 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was Seneca ST over I-5 built?

It was built in 1964, making it 61 years old in 2025.

What condition is Seneca ST over I-5 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 August 2023.

How much traffic does Seneca ST over I-5 carry?

About 10,000 vehicles per day (2017 count), of which roughly 5% are trucks.

How long is Seneca ST over I-5?

The structure is 250 ft (76.2 m) long with a longest span of 96 ft (29.3 m) and a deck 62 ft wide.

Who owns Seneca ST over I-5?

It is owned by the State Highway Agency.