US Bridges

Knapp Road over Nookachamps Creek

Fair

Skagit County, Washington · 0.1 E JCT SR 9 · Structure no. 083068000000000

Built
1977
48 years old
Condition
Fair
inspected August 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
73 ft
1 main span
Daily traffic
405
2023 count
Owner
County
County Highway Agency

About this bridge

Knapp Road over Nookachamps Creek is a prestressed concrete stringer/multi-beam or girder carrying Knapp Road over Nookachamps Creek in Skagit County, Washington. It was built in 1977, so it is 48 years old, younger 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 405 vehicles a day, roughly 10% of them trucks, projected to reach 602 by 2043. The structure is 73 ft (22.3 m) long and 31 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

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CarriesKnapp Road
CrossesNookachamps Creek
Location0.1 E JCT SR 9
RouteCounty Highway 4130
CountySkagit County
StateWashington
Coordinates48.42861, -122.25906
Functional classRural Local

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.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionAugust 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 adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating68 US tons
Inventory rating40 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckOther
Main spans1
Design loadHS 20
Structure length73 ft (22.3 m)
Longest span70 ft (21.3 m)
Deck width31 ft (9.3 m)
Roadway width28 ft (8.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic405 (2023)
Projected traffic602 by 2043
Trucks10%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.1 mi (5 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$902,000 (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Knapp Road over Nookachamps Creek built?

It was built in 1977, making it 48 years old in 2025.

What condition is Knapp Road over Nookachamps 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 August 2023.

How much traffic does Knapp Road over Nookachamps Creek carry?

About 405 vehicles per day (2023 count), of which roughly 10% are trucks.

How long is Knapp Road over Nookachamps Creek?

The structure is 73 ft (22.3 m) long with a longest span of 70 ft (21.3 m) and a deck 31 ft wide.

Who owns Knapp Road over Nookachamps Creek?

It is owned by the County Highway Agency.