US Bridges

SR 20 over Deception Pass

Fair

Island County, Washington · 25.4 E JCT SR 525 · Structure no. 0001929A0000000

Built
1935
90 years old
Condition
Fair
inspected February 2023
Type
Truss - Deck
Steel
Length
976 ft
3 main spans
Daily traffic
18,797
2023 count
Owner
State
State Highway Agency

About this bridge

SR 20 over Deception Pass is a steel truss - deck carrying SR 20 over Deception Pass in Island County, Washington. It was built in 1935, so it is 90 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 18,797 vehicles a day, roughly 6% of them trucks, projected to reach 26,979 by 2039. The structure is 976 ft (297.5 m) long and 30 ft wide. If it were closed, the detour would be 98.8 mi (159 km).

Location

Open in Google Maps
CarriesSR 20
CrossesDeception Pass
Location25.4 E JCT SR 525
RouteState Highway 20
CountyIsland County
StateWashington
Coordinates48.40722, -122.64456
Functional classRural Principal Arterial - Other

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.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionFebruary 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations on dry land well above flood water elevations
Structural evaluation3: Basically intolerable, requiring high priority of corrective action
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating17.2 US tons
Inventory rating13.2 US tons

Structure

Structure typeTruss - Deck
MaterialSteel
DeckConcrete, cast-in-place
Main spans3 (+4 approach)
Design loadH 15
Structure length976 ft (297.5 m)
Longest span550 ft (167.6 m)
Deck width30 ft (9.1 m)
Roadway width22 ft (6.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic18,797 (2023)
Projected traffic26,979 by 2039
Trucks6%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed98.8 mi (159 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkSTRAHNET connector

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusListed on the National Register of Historic Places
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$15.8 million (2022 estimate)
NavigationNavigation control on waterway (bridge permit required)

Frequently asked questions

When was SR 20 over Deception Pass built?

It was built in 1935, making it 90 years old in 2025.

What condition is SR 20 over Deception Pass 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 February 2023.

How much traffic does SR 20 over Deception Pass carry?

About 18,797 vehicles per day (2023 count), of which roughly 6% are trucks.

How long is SR 20 over Deception Pass?

The structure is 976 ft (297.5 m) long with a longest span of 550 ft (167.6 m) and a deck 30 ft wide.

Who owns SR 20 over Deception Pass?

It is owned by the State Highway Agency.