US Bridges

Hevly RD over Stillaguamish Slough

Fair

Snohomish County, Washington · 0.8 NE SR530 · Structure no. 087238000000000

Built
2005
20 years old
Condition
Fair
inspected June 2023
Type
Channel Beam
Concrete
Length
81 ft
4 main spans
Daily traffic
71
2022 count
Owner
County
County Highway Agency

About this bridge

Hevly RD over Stillaguamish Slough is a concrete channel beam carrying Hevly RD over Stillaguamish Slough 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 5 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 71 vehicles a day, roughly 20% of them trucks, projected to reach 150 by 2045. The structure is 81 ft (24.6 m) long and 24 ft wide. If it were closed, the detour would be 98.8 mi (159 km).

Location

Open in Google Maps
CarriesHevly RD
CrossesStillaguamish Slough
Location0.8 NE SR530
RouteCounty Highway 64580
CountySnohomish County
StateWashington
Coordinates48.20186, -122.23428
Functional classRural Local

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.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJune 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
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 rating41 US tons
Inventory rating24 US tons

Structure

Structure typeChannel Beam
MaterialConcrete
DeckOther
Main spans4
Design loadHS 15
Structure length81 ft (24.6 m)
Longest span20 ft (6.1 m)
Deck width24 ft (7.4 m)
Roadway width23 ft (7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic71 (2022)
Projected traffic150 by 2045
Trucks20%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed98.8 mi (159 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$3.3 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Hevly RD over Stillaguamish Slough built?

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

What condition is Hevly RD over Stillaguamish Slough 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 June 2023.

How much traffic does Hevly RD over Stillaguamish Slough carry?

About 71 vehicles per day (2022 count), of which roughly 20% are trucks.

How long is Hevly RD over Stillaguamish Slough?

The structure is 81 ft (24.6 m) long with a longest span of 20 ft (6.1 m) and a deck 24 ft wide.

Who owns Hevly RD over Stillaguamish Slough?

It is owned by the County Highway Agency.