US Bridges

SR 530 over S Fk Stillaguamish R

Good

Snohomish County, Washington · 0.5 E JCT SR 9 · Structure no. 0014820A0000000

Built
1997
28 years old
Condition
Good
inspected June 2024
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
596 ft
4 main spans
Daily traffic
13,355
2023 count
Owner
State
State Highway Agency

About this bridge

SR 530 over S Fk Stillaguamish R is a steel continuous stringer/multi-beam or girder carrying SR 530 over S Fk Stillaguamish R in Snohomish County, Washington. It was built in 1997, so it is 28 years old, younger 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.

It carries about 13,355 vehicles a day, roughly 7% of them trucks, projected to reach 19,620 by 2039. The structure is 596 ft (181.7 m) long and 51 ft wide. If it were closed, the detour would be 98.8 mi (159 km).

Location

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CarriesSR 530
CrossesS Fk Stillaguamish R
Location0.5 E JCT SR 9
RouteState Highway 530
CountySnohomish County
StateWashington
Coordinates48.20039, -122.11922
Functional classUrban Minor Arterial

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.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionJune 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation7: Better than present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating66 US tons
Inventory rating40 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadHS 25 or greater
Structure length596 ft (181.7 m)
Longest span176 ft (53.6 m)
Deck width51 ft (15.5 m)
Roadway width39 ft (11.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic13,355 (2023)
Projected traffic19,620 by 2039
Trucks7%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed98.8 mi (159 km)
TollOn a free road
National Highway SystemNo

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$11.6 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SR 530 over S Fk Stillaguamish R built?

It was built in 1997, making it 28 years old in 2025.

What condition is SR 530 over S Fk Stillaguamish R 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 June 2024.

How much traffic does SR 530 over S Fk Stillaguamish R carry?

About 13,355 vehicles per day (2023 count), of which roughly 7% are trucks.

How long is SR 530 over S Fk Stillaguamish R?

The structure is 596 ft (181.7 m) long with a longest span of 176 ft (53.6 m) and a deck 51 ft wide.

Who owns SR 530 over S Fk Stillaguamish R?

It is owned by the State Highway Agency.