US Bridges

SR 11 over Half Bridge

Fair

Skagit County, Washington · 13.1 N JCT I-5 · Structure no. 0000453A0000000

Built
1920
105 years old
Condition
Fair
inspected August 2024
Type
Girder and Floorbeam System
Concrete Continuous
Length
145 ft
6 main spans
Daily traffic
2,472
2023 count
Owner
State
State Highway Agency

About this bridge

SR 11 over Half Bridge is a concrete continuous girder and floorbeam system carrying SR 11 over Half Bridge in Skagit County, Washington. It was built in 1920, so it is 105 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 2,472 vehicles a day, roughly 4% of them trucks, projected to reach 3,569 by 2039. The structure is 145 ft (44.2 m) long and 21 ft wide. If it were closed, the detour would be 29.2 mi (47 km).

Location

Open in Google Maps
CarriesSR 11
CrossesHalf Bridge
Location13.1 N JCT I-5
RouteState Highway 11
CountySkagit County
StateWashington
Coordinates48.63375, -122.47231
Functional classRural Major Collector

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.
Last inspectionAugust 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry2: Basically intolerable, requiring high priority of replacement
Approach roadway alignment6: Equal to present minimum criteria
Operating rating25 US tons
Inventory rating15 US tons

Structure

Structure typeGirder and Floorbeam System
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans6
Design loadUnknown
Structure length145 ft (44.2 m)
Longest span24 ft (7.3 m)
Deck width21 ft (6.5 m)
Roadway width20 ft (6.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,472 (2023)
Projected traffic3,569 by 2039
Trucks4%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesOther
Detour if closed29.2 mi (47 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$1.4 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was SR 11 over Half Bridge built?

It was built in 1920, making it 105 years old in 2025.

What condition is SR 11 over Half Bridge 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 August 2024.

How much traffic does SR 11 over Half Bridge carry?

About 2,472 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is SR 11 over Half Bridge?

The structure is 145 ft (44.2 m) long with a longest span of 24 ft (7.3 m) and a deck 21 ft wide.

Who owns SR 11 over Half Bridge?

It is owned by the State Highway Agency.