US Bridges

SR 529 over Union Sl

Poor

Snohomish County, Washington · 5.9 N JCT SR 529 Spur · Structure no. 0004562A0000000

Built
1954
71 years old
Condition
Poor
inspected July 2023
Type
Tee Beam
Concrete Continuous
Length
633 ft
12 main spans
Daily traffic
16,439
2023 count
Owner
State
State Highway Agency

About this bridge

SR 529 over Union Sl is a concrete continuous tee beam carrying SR 529 over Union Sl 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 16,439 vehicles a day, roughly 6% of them trucks, projected to reach 24,643 by 2039. The structure is 633 ft (192.9 m) long and 35 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesSR 529
CrossesUnion Sl
Location5.9 N JCT SR 529 Spur
RouteState Highway 529
CountySnohomish County
StateWashington
Coordinates48.03047, -122.18297
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
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure4 PoorAdvanced section loss, deterioration, spalling or scour.
Channel and channel protection7 GoodSome minor problems.
Last inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; action required to protect exposed foundations
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 alignment8: Equal to present desirable criteria
Operating rating36.4 US tons
Inventory rating28.2 US tons

Structure

Structure typeTee Beam
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans12
Design loadHS 20
Structure length633 ft (192.9 m)
Longest span62 ft (18.9 m)
Deck width35 ft (10.8 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic16,439 (2023)
Projected traffic24,643 by 2039
Trucks6%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway and pedestrian
CrossesWaterway
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 statusNot eligible for the National Register of Historic Places
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$10.8 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SR 529 over Union Sl built?

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

What condition is SR 529 over Union Sl 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 Union Sl carry?

About 16,439 vehicles per day (2023 count), of which roughly 6% are trucks.

How long is SR 529 over Union Sl?

The structure is 633 ft (192.9 m) long with a longest span of 62 ft (18.9 m) and a deck 35 ft wide.

Who owns SR 529 over Union Sl?

It is owned by the State Highway Agency.