US Bridges

Larch Way over Swamp Creek

Fair

Snohomish County, Washington · 1.4 SW Int I-405 · Structure no. 083075000000000

Built
1963
62 years old
Condition
Fair
inspected December 2023
Type
Channel Beam
Concrete
Length
26 ft
1 main span
Daily traffic
10,030
2022 count
Owner
County
County Highway Agency

About this bridge

Larch Way over Swamp Creek is a concrete channel beam carrying Larch Way over Swamp Creek in Snohomish County, Washington. It was built in 1963, so it is 62 years old, older 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 10,030 vehicles a day, roughly 7% of them trucks, projected to reach 14,000 by 2041. The structure is 26 ft (7.8 m) long and 24 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesLarch Way
CrossesSwamp Creek
Location1.4 SW Int I-405
RouteCounty Highway 90616
CountySnohomish County
StateWashington
Coordinates47.80827, -122.25604
Functional classUrban Minor 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
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionDecember 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 geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating59 US tons
Inventory rating34.9 US tons

Structure

Structure typeChannel Beam
MaterialConcrete
DeckOther
Main spans1
Design loadH 15
Structure length26 ft (7.8 m)
Longest span24 ft (7.3 m)
Deck width24 ft (7.3 m)
Roadway width23 ft (6.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic10,030 (2022)
Projected traffic14,000 by 2041
Trucks7%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed1.9 mi (3 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$1.3 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Larch Way over Swamp Creek built?

It was built in 1963, making it 62 years old in 2025.

What condition is Larch Way over Swamp Creek 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 December 2023.

How much traffic does Larch Way over Swamp Creek carry?

About 10,030 vehicles per day (2022 count), of which roughly 7% are trucks.

How long is Larch Way over Swamp Creek?

The structure is 26 ft (7.8 m) long with a longest span of 24 ft (7.3 m) and a deck 24 ft wide.

Who owns Larch Way over Swamp Creek?

It is owned by the County Highway Agency.