US Bridges

SR 529 over Snohomish River

Poor

Snohomish County, Washington · 4.7 N JCT SR 529 Spur · Structure no. 0004331A0000000

Built
1954
71 years old
Condition
Poor
inspected July 2023
Type
Movable - Lift
Steel
Length
2,465 ft
1 main span
Daily traffic
16,286
2023 count
Owner
State
State Highway Agency

About this bridge

SR 529 over Snohomish River is a steel movable - lift carrying SR 529 over Snohomish River in Snohomish County, Washington. It was built in 1954, so it is 71 years old, older than the Washington average of 49.8 years.

The most recent inspection reported to the Federal Highway Administration rates it in poor condition with a lowest component rating of 4 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

It carries about 16,286 vehicles a day, roughly 6% of them trucks, projected to reach 24,967 by 2039. The structure is 2,465 ft (751.3 m) long and 35 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesSR 529
CrossesSnohomish River
Location4.7 N JCT SR 529 Spur
RouteState Highway 529
CountySnohomish County
StateWashington
Coordinates48.01267, -122.18931
Functional classUrban Principal Arterial - Other Freeway or Expressway

Condition and inspection

Poor

The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure4 PoorAdvanced section loss, deterioration, spalling or scour.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating48.9 US tons
Inventory rating29 US tons

Structure

Structure typeMovable - Lift
MaterialSteel
DeckConcrete, cast-in-place
Main spans1 (+28 approach)
Design loadHS 20
Structure length2,465 ft (751.3 m)
Longest span240 ft (73.2 m)
Deck width35 ft (10.6 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deck15 ft (4.6 m)

Traffic and service

Average daily traffic16,286 (2023)
Projected traffic24,967 by 2039
Trucks6%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway and pedestrian
CrossesHighway, waterway and railroad
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 statusEligible for the National Register of Historic Places
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$44.5 million (2022 estimate)
NavigationNavigation control on waterway (bridge permit required)

Frequently asked questions

When was SR 529 over Snohomish River built?

It was built in 1954, making it 71 years old in 2025.

What condition is SR 529 over Snohomish River in?

The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in July 2023.

How much traffic does SR 529 over Snohomish River carry?

About 16,286 vehicles per day (2023 count), of which roughly 6% are trucks.

How long is SR 529 over Snohomish River?

The structure is 2,465 ft (751.3 m) long with a longest span of 240 ft (73.2 m) and a deck 35 ft wide.

Who owns SR 529 over Snohomish River?

It is owned by the State Highway Agency.