US Bridges

I-5 over Iowa ST

Fair

Whatcom County, Washington · 3.1 N JCT SR 11 · Structure no. 0005468A0000000

Built
1957
68 years old
Condition
Fair
inspected October 2024
Type
Slab
Concrete Continuous
Length
138 ft
3 main spans
Daily traffic
33,565
2023 count
Owner
State
State Highway Agency

About this bridge

I-5 over Iowa ST is a concrete continuous slab carrying I-5 over Iowa ST in Whatcom County, Washington. It was built in 1957, so it is 68 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 33,565 vehicles a day, roughly 7% of them trucks, projected to reach 47,631 by 2039. The structure is 138 ft (42.1 m) long and 98 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesI-5
CrossesIowa ST
Location3.1 N JCT SR 11
RouteInterstate 5
CountyWhatcom County
StateWashington
Coordinates48.75628, -122.46169
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.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionOctober 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating75 US tons
Inventory rating45 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length138 ft (42.1 m)
Longest span56 ft (17.1 m)
Deck width98 ft (29.8 m)
Roadway width90 ft (27.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic33,565 (2023)
Projected traffic47,631 by 2039
Trucks7%
Lanes on structure5
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed1.9 mi (3 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$6 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was I-5 over Iowa ST built?

It was built in 1957, making it 68 years old in 2025.

What condition is I-5 over Iowa ST 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 October 2024.

How much traffic does I-5 over Iowa ST carry?

About 33,565 vehicles per day (2023 count), of which roughly 7% are trucks.

How long is I-5 over Iowa ST?

The structure is 138 ft (42.1 m) long with a longest span of 56 ft (17.1 m) and a deck 98 ft wide.

Who owns I-5 over Iowa ST?

It is owned by the State Highway Agency.