US Bridges

20th Avenue West over RD to Boeing Parking Lot

Fair

Snohomish County, Washington · Boeing Intrchng · Structure no. 085160000000000

Built
1969
56 years old
Condition
Fair
inspected November 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
148 ft
3 main spans
Daily traffic
19,626
2022 count
Owner
City
City or Municipal Highway Agency

About this bridge

20th Avenue West over RD to Boeing Parking Lot is a prestressed concrete stringer/multi-beam or girder carrying 20th Avenue West over RD to Boeing Parking Lot in Snohomish County, Washington. It was built in 1969, so it is 56 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 6 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 19,626 vehicles a day, roughly 7% of them trucks, projected to reach 24,000 by 2046. The structure is 148 ft (45.2 m) long and 93 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

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Carries20th Avenue West
CrossesRD to Boeing Parking Lot
LocationBoeing Intrchng
RouteCity Street 420
CountySnohomish County
StateWashington
Coordinates47.92934, -122.26071
Functional classUrban Other Principal 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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionNovember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating45 US tons
Inventory rating27 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length148 ft (45.2 m)
Longest span62 ft (19 m)
Deck width93 ft (28.3 m)
Roadway width90 ft (27.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic19,626 (2022)
Projected traffic24,000 by 2046
Trucks7%
Lanes on structure6
Traffic directionTwo-way traffic
CarriesOverpass structure at an interchange
CrossesHighway
Detour if closed3.7 mi (6 km)
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$12.9 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was 20th Avenue West over RD to Boeing Parking Lot built?

It was built in 1969, making it 56 years old in 2025.

What condition is 20th Avenue West over RD to Boeing Parking Lot 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 November 2024.

How much traffic does 20th Avenue West over RD to Boeing Parking Lot carry?

About 19,626 vehicles per day (2022 count), of which roughly 7% are trucks.

How long is 20th Avenue West over RD to Boeing Parking Lot?

The structure is 148 ft (45.2 m) long with a longest span of 62 ft (19 m) and a deck 93 ft wide.

Who owns 20th Avenue West over RD to Boeing Parking Lot?

It is owned by the City or Municipal Highway Agency.