US Bridges

I-405 NB to I-5 SB over Ramps and Swamp Creek

Fair

Snohomish County, Washington · JCT I-5 · Structure no. 0011855B0000000

Built
1981
44 years old
Condition
Fair
inspected April 2024
Type
Box Beam or Girders - Multiple
Concrete Continuous
Length
1,270 ft
11 main spans
Daily traffic
13,933
2023 count
Owner
State
State Highway Agency

About this bridge

I-405 NB to I-5 SB over Ramps and Swamp Creek is a concrete continuous box beam or girders - multiple carrying I-405 NB to I-5 SB over Ramps and Swamp Creek in Snohomish County, Washington. It was built in 1981, so it is 44 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 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 13,933 vehicles a day, roughly 5% of them trucks, projected to reach 20,699 by 2039. The structure is 1,270 ft (387.1 m) long and 31 ft wide. If it were closed, the detour would be 6.2 mi (10 km).

Location

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CarriesI-405 NB to I-5 SB
CrossesRamps and Swamp Creek
LocationJCT I-5
RouteInterstate 405
CountySnohomish County
StateWashington
Coordinates47.83372, -122.26464
Functional classUrban Principal Arterial - Interstate

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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionApril 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Deck geometry9: Superior to present desirable criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating74 US tons
Inventory rating44 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans11
Design loadHS 20 + Mod
Structure length1,270 ft (387.1 m)
Longest span140 ft (42.7 m)
Deck width31 ft (9.4 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic13,933 (2023)
Projected traffic20,699 by 2039
Trucks5%
Lanes on structure1
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway and waterway
Detour if closed6.2 mi (10 km)
TollOn a free road
National Highway SystemYes

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$20.5 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was I-405 NB to I-5 SB over Ramps and Swamp Creek built?

It was built in 1981, making it 44 years old in 2025.

What condition is I-405 NB to I-5 SB over Ramps and 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 April 2024.

How much traffic does I-405 NB to I-5 SB over Ramps and Swamp Creek carry?

About 13,933 vehicles per day (2023 count), of which roughly 5% are trucks.

How long is I-405 NB to I-5 SB over Ramps and Swamp Creek?

The structure is 1,270 ft (387.1 m) long with a longest span of 140 ft (42.7 m) and a deck 31 ft wide.

Who owns I-405 NB to I-5 SB over Ramps and Swamp Creek?

It is owned by the State Highway Agency.