US Bridges

I-5 over Skagit River

Fair

Skagit County, Washington · 0.7 N JCT SR 538 · Structure no. 0004794A0000000

Built
1955
70 years old
Condition
Fair
inspected June 2023
Type
Truss - Thru
Steel
Length
1,112 ft
3 main spans
Daily traffic
39,245
2023 count
Owner
State
State Highway Agency

About this bridge

I-5 over Skagit River is a steel truss - thru carrying I-5 over Skagit River in Skagit County, Washington. It was built in 1955, so it is 70 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 39,245 vehicles a day, roughly 10% of them trucks, projected to reach 59,435 by 2039. The structure is 1,112 ft (338.9 m) long and 60 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesI-5
CrossesSkagit River
Location0.7 N JCT SR 538
RouteInterstate 5
CountySkagit County
StateWashington
Coordinates48.44331, -122.34103
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.
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 protection8 Very GoodNo problems noted.
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 geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating50 US tons
Inventory rating30 US tons

Structure

Structure typeTruss - Thru
MaterialSteel
DeckConcrete, cast-in-place
Main spans3 (+9 approach)
Design loadHS 20
Structure length1,112 ft (338.9 m)
Longest span160 ft (48.8 m)
Deck width60 ft (18.3 m)
Roadway width55 ft (16.9 m)
Vertical clearance over deck18 ft (5.4 m)

Traffic and service

Average daily traffic39,245 (2023)
Projected traffic59,435 by 2039
Trucks10%
Lanes on structure4
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway and waterway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$39.1 million (2022 estimate)
NavigationNavigation control on waterway (bridge permit required)

Frequently asked questions

When was I-5 over Skagit River built?

It was built in 1955, making it 70 years old in 2025.

What condition is I-5 over Skagit River 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 I-5 over Skagit River carry?

About 39,245 vehicles per day (2023 count), of which roughly 10% are trucks.

How long is I-5 over Skagit River?

The structure is 1,112 ft (338.9 m) long with a longest span of 160 ft (48.8 m) and a deck 60 ft wide.

Who owns I-5 over Skagit River?

It is owned by the State Highway Agency.