US Bridges

I-5 over Colony RD

Fair

Skagit County, Washington · 8.8 N JCT SR 11 · Structure no. 0007260B0000000

Built
1963
62 years old
Condition
Fair
inspected March 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
273 ft
4 main spans
Daily traffic
24,437
2023 count
Owner
State
State Highway Agency

About this bridge

I-5 over Colony RD is a prestressed concrete stringer/multi-beam or girder carrying I-5 over Colony RD in Skagit 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 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 24,437 vehicles a day, roughly 7% of them trucks, projected to reach 35,328 by 2039. The structure is 273 ft (83.2 m) long and 35 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
CarriesI-5
CrossesColony RD
Location8.8 N JCT SR 11
RouteInterstate 5
CountySkagit County
StateWashington
Coordinates48.60891, -122.34792
Functional classRural 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.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Last inspectionMarch 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating36.4 US tons
Inventory rating28.2 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20
Structure length273 ft (83.2 m)
Longest span75 ft (22.9 m)
Deck width35 ft (10.7 m)
Roadway width32 ft (9.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic24,437 (2023)
Projected traffic35,328 by 2039
Trucks7%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed3.7 mi (6 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 statusHistorical significance not determinable at this time
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$5.4 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was I-5 over Colony RD built?

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

What condition is I-5 over Colony RD 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 March 2023.

How much traffic does I-5 over Colony RD carry?

About 24,437 vehicles per day (2023 count), of which roughly 7% are trucks.

How long is I-5 over Colony RD?

The structure is 273 ft (83.2 m) long with a longest span of 75 ft (22.9 m) and a deck 35 ft wide.

Who owns I-5 over Colony RD?

It is owned by the State Highway Agency.