US Bridges

SR 20 over Swift Creek

Good

Skagit County, Washington · 2.0 E JCT SR 530 · Structure no. 0005051A0000000

Built
1955
70 years old
Condition
Good
inspected April 2021
Type
Slab
Concrete Continuous
Length
80 ft
3 main spans
Daily traffic
2,492
2023 count
Owner
State
State Highway Agency

About this bridge

SR 20 over Swift Creek is a concrete continuous slab carrying SR 20 over Swift Creek 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 good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 2,492 vehicles a day, roughly 7% of them trucks, projected to reach 3,597 by 2039. The structure is 80 ft (24.4 m) long and 31 ft wide. If it were closed, the detour would be 23 mi (37 km).

Location

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CarriesSR 20
CrossesSwift Creek
Location2.0 E JCT SR 530
RouteState Highway 20
CountySkagit County
StateWashington
Coordinates48.49243, -121.55021
Functional classRural Minor Arterial

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionApril 2021
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation7: Better than present minimum criteria
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating61 US tons
Inventory rating36 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length80 ft (24.4 m)
Longest span32 ft (9.8 m)
Deck width31 ft (9.6 m)
Roadway width26 ft (7.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,492 (2023)
Projected traffic3,597 by 2039
Trucks7%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed23 mi (37 km)
TollOn a free road
National Highway SystemNo

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$1.1 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SR 20 over Swift Creek built?

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

What condition is SR 20 over Swift Creek in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in April 2021.

How much traffic does SR 20 over Swift Creek carry?

About 2,492 vehicles per day (2023 count), of which roughly 7% are trucks.

How long is SR 20 over Swift Creek?

The structure is 80 ft (24.4 m) long with a longest span of 32 ft (9.8 m) and a deck 31 ft wide.

Who owns SR 20 over Swift Creek?

It is owned by the State Highway Agency.