US Bridges

SR 527 over I-405

Fair

Snohomish County, Washington · JCT I-405 · Structure no. 0008286B0000000

Built
1968
57 years old, rebuilt 2001
Condition
Fair
inspected January 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete Continuous
Length
341 ft
4 main spans
Daily traffic
53,140
2023 count
Owner
State
State Highway Agency

About this bridge

SR 527 over I-405 is a prestressed concrete continuous stringer/multi-beam or girder carrying SR 527 over I-405 in Snohomish County, Washington. It was built in 1968 and reconstructed in 2001, so it is 57 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 53,140 vehicles a day, roughly 3% of them trucks, projected to reach 80,125 by 2039. The structure is 341 ft (103.9 m) long and 77 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

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CarriesSR 527
CrossesI-405
LocationJCT I-405
RouteState Highway 527
CountySnohomish County
StateWashington
Coordinates47.79444, -122.2145
Functional classUrban Other Principal 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
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Last inspectionJanuary 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to 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 rating67 US tons
Inventory rating39 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20 + Mod
Structure length341 ft (103.9 m)
Longest span113 ft (34.4 m)
Deck width77 ft (23.6 m)
Roadway width67 ft (20.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic53,140 (2023)
Projected traffic80,125 by 2039
Trucks3%
Lanes on structure5
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesHighway
Detour if closed3.7 mi (6 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$12.5 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was SR 527 over I-405 built?

It was built in 1968, making it 57 years old in 2025. It was reconstructed in 2001.

What condition is SR 527 over I-405 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 January 2024.

How much traffic does SR 527 over I-405 carry?

About 53,140 vehicles per day (2023 count), of which roughly 3% are trucks.

How long is SR 527 over I-405?

The structure is 341 ft (103.9 m) long with a longest span of 113 ft (34.4 m) and a deck 77 ft wide.

Who owns SR 527 over I-405?

It is owned by the State Highway Agency.