US Bridges

I-405 over Pedestrian Trail

GoodPosted for load

King County, Washington · 5.2 N JCT SR 520 · Structure no. 0004978A0000000

Built
1956
69 years old, rebuilt 1994
Condition
Good
inspected July 2023
Type
Tee Beam
Concrete Continuous
Length
199 ft
3 main spans
Daily traffic
85,426
2023 count
Owner
State
State Highway Agency

About this bridge

I-405 over Pedestrian Trail is a concrete continuous tee beam carrying I-405 over Pedestrian Trail in King County, Washington. It was built in 1956 and reconstructed in 1994, so it is 69 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. Its operating status is: posted for load restriction.

It carries about 85,426 vehicles a day, roughly 6% of them trucks, projected to reach 129,261 by 2039. The structure is 199 ft (60.7 m) long and 107 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesI-405
CrossesPedestrian Trail
Location5.2 N JCT SR 520
RouteInterstate 405
CountyKing County
StateWashington
Coordinates47.70594, -122.18001
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 inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourBridge not over waterway
Structural evaluation3: Basically intolerable, requiring high priority of corrective action
Deck geometry9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating21.8 US tons
Inventory rating16.8 US tons

Structure

Structure typeTee Beam
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20 + Mod
Structure length199 ft (60.7 m)
Longest span77 ft (23.5 m)
Deck width107 ft (32.6 m)
Roadway width104 ft (31.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic85,426 (2023)
Projected traffic129,261 by 2039
Trucks6%
Lanes on structure6
Traffic directionOne-way traffic
CarriesHighway
CrossesPedestrian / bicycle
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

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$10 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was I-405 over Pedestrian Trail built?

It was built in 1956, making it 69 years old in 2025. It was reconstructed in 1994.

What condition is I-405 over Pedestrian Trail 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 July 2023.

How much traffic does I-405 over Pedestrian Trail carry?

About 85,426 vehicles per day (2023 count), of which roughly 6% are trucks.

How long is I-405 over Pedestrian Trail?

The structure is 199 ft (60.7 m) long with a longest span of 77 ft (23.5 m) and a deck 107 ft wide.

Who owns I-405 over Pedestrian Trail?

It is owned by the State Highway Agency.