US Bridges

SR 531 over I-5

Fair

Snohomish County, Washington · JCT I-5 · Structure no. 0016801A0000000

Built
2005
20 years old
Condition
Fair
inspected August 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete Continuous
Length
243 ft
2 main spans
Daily traffic
32,637
2023 count
Owner
State
State Highway Agency

About this bridge

SR 531 over I-5 is a prestressed concrete continuous stringer/multi-beam or girder carrying SR 531 over I-5 in Snohomish County, Washington. It was built in 2005, so it is 20 years old, younger 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 32,637 vehicles a day, roughly 3% of them trucks, projected to reach 48,518 by 2039. The structure is 243 ft (74.1 m) long and 99 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

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CarriesSR 531
CrossesI-5
LocationJCT I-5
RouteState Highway 531
CountySnohomish County
StateWashington
Coordinates48.15233, -122.18939
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Last inspectionAugust 2024
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 rating99 US tons
Inventory rating70 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadHL 93
Structure length243 ft (74.1 m)
Longest span121 ft (37 m)
Deck width99 ft (30.1 m)
Roadway width84 ft (25.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic32,637 (2023)
Projected traffic48,518 by 2039
Trucks3%
Lanes on structure6
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 statusHistorical significance not determinable at this time
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$9.9 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was SR 531 over I-5 built?

It was built in 2005, making it 20 years old in 2025.

What condition is SR 531 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 2024.

How much traffic does SR 531 over I-5 carry?

About 32,637 vehicles per day (2023 count), of which roughly 3% are trucks.

How long is SR 531 over I-5?

The structure is 243 ft (74.1 m) long with a longest span of 121 ft (37 m) and a deck 99 ft wide.

Who owns SR 531 over I-5?

It is owned by the State Highway Agency.