US Bridges

SR 20 over Rocky Creek

Fair

Skagit County, Washington · 4.6 E JCT SR 530 · Structure no. 0003226A0000000

Built
1947
78 years old
Condition
Fair
inspected May 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
128 ft
3 main spans
Daily traffic
2,492
2023 count
Owner
State
State Highway Agency

About this bridge

SR 20 over Rocky Creek is a steel stringer/multi-beam or girder carrying SR 20 over Rocky Creek in Skagit County, Washington. It was built in 1947, so it is 78 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 2,492 vehicles a day, roughly 7% of them trucks, projected to reach 3,597 by 2039. The structure is 128 ft (39 m) long and 29 ft wide. If it were closed, the detour would be 23 mi (37 km).

Location

Open in Google Maps
CarriesSR 20
CrossesRocky Creek
Location4.6 E JCT SR 530
RouteState Highway 20
CountySkagit County
StateWashington
Coordinates48.50572, -121.49703
Functional classRural Minor Arterial

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.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionMay 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation6: Equal to 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 rating72 US tons
Inventory rating43 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length128 ft (39 m)
Longest span60 ft (18.3 m)
Deck width29 ft (8.7 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$1.9 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SR 20 over Rocky Creek built?

It was built in 1947, making it 78 years old in 2025.

What condition is SR 20 over Rocky 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 May 2024.

How much traffic does SR 20 over Rocky Creek carry?

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

How long is SR 20 over Rocky Creek?

The structure is 128 ft (39 m) long with a longest span of 60 ft (18.3 m) and a deck 29 ft wide.

Who owns SR 20 over Rocky Creek?

It is owned by the State Highway Agency.