US Bridges

Prairie Road over Samish River

Fair

Skagit County, Washington · 3.8 E JCT Old HWY 99 · Structure no. 084514000000000

Built
1975
50 years old
Condition
Fair
inspected September 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
104 ft
1 main span
Daily traffic
1,539
2021 count
Owner
County
County Highway Agency

About this bridge

Prairie Road over Samish River is a prestressed concrete stringer/multi-beam or girder carrying Prairie Road over Samish River in Skagit County, Washington. It was built in 1975, so it is 50 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 1,539 vehicles a day, roughly 11% of them trucks, projected to reach 2,286 by 2041. The structure is 104 ft (31.7 m) long and 30 ft wide. If it were closed, the detour would be 8.7 mi (14 km).

Location

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CarriesPrairie Road
CrossesSamish River
Location3.8 E JCT Old HWY 99
RouteCounty Highway 50000
CountySkagit County
StateWashington
Coordinates48.56928, -122.29875
Functional classRural Minor 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
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating73.5 US tons
Inventory rating44 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length104 ft (31.7 m)
Longest span101 ft (30.8 m)
Deck width30 ft (9.1 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,539 (2021)
Projected traffic2,286 by 2041
Trucks11%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed8.7 mi (14 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedDeck rehabilitation with only incidental widening
Estimated improvement cost$1.4 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Prairie Road over Samish River built?

It was built in 1975, making it 50 years old in 2025.

What condition is Prairie Road over Samish River 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 September 2023.

How much traffic does Prairie Road over Samish River carry?

About 1,539 vehicles per day (2021 count), of which roughly 11% are trucks.

How long is Prairie Road over Samish River?

The structure is 104 ft (31.7 m) long with a longest span of 101 ft (30.8 m) and a deck 30 ft wide.

Who owns Prairie Road over Samish River?

It is owned by the County Highway Agency.