US Bridges

SR 20 over Higgins Slough

Good

Skagit County, Washington · 0.1 E JCT SR 536 · Structure no. 0017242A0000000

Built
2007
18 years old
Condition
Good
inspected March 2022
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
100 ft
1 main span
Daily traffic
13,561
2023 count
Owner
State
State Highway Agency

About this bridge

SR 20 over Higgins Slough is a prestressed concrete stringer/multi-beam or girder carrying SR 20 over Higgins Slough in Skagit County, Washington. It was built in 2007, so it is 18 years old, younger 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 13,561 vehicles a day, roughly 8% of them trucks, projected to reach 19,077 by 2039. The structure is 100 ft (30.5 m) long and 40 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesSR 20
CrossesHiggins Slough
Location0.1 E JCT SR 536
RouteState Highway 20
CountySkagit County
StateWashington
Coordinates48.44635, -122.43096
Functional classRural Principal Arterial - Other

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 protection8 Very GoodNo problems noted.
Last inspectionMarch 2022
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation7: Better than present minimum criteria
Deck geometry7: Better than present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating85 US tons
Inventory rating51 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHL 93
Structure length100 ft (30.5 m)
Longest span100 ft (30.5 m)
Deck width40 ft (12.1 m)
Roadway width38 ft (11.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic13,561 (2023)
Projected traffic19,077 by 2039
Trucks8%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkSTRAHNET connector

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$1.2 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SR 20 over Higgins Slough built?

It was built in 2007, making it 18 years old in 2025.

What condition is SR 20 over Higgins Slough 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 March 2022.

How much traffic does SR 20 over Higgins Slough carry?

About 13,561 vehicles per day (2023 count), of which roughly 8% are trucks.

How long is SR 20 over Higgins Slough?

The structure is 100 ft (30.5 m) long with a longest span of 100 ft (30.5 m) and a deck 40 ft wide.

Who owns SR 20 over Higgins Slough?

It is owned by the State Highway Agency.