US Bridges

County Arterial over Wahluke Branch Canal

FairPosted for load

Franklin County, Washington · 1.36W Columbia 416 · Structure no. 083157000000000

Built
1959
66 years old
Condition
Fair
inspected December 2023
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
28 ft
1 main span
Daily traffic
357
2023 count
Owner
County
County Highway Agency

About this bridge

County Arterial over Wahluke Branch Canal is a wood or timber stringer/multi-beam or girder carrying County Arterial over Wahluke Branch Canal in Franklin County, Washington. It was built in 1959, so it is 66 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. Its operating status is: posted for load restriction.

It carries about 357 vehicles a day, roughly 37% of them trucks, projected to reach 1,110 by 2040. The structure is 28 ft (8.5 m) long and 25 ft wide. If it were closed, the detour would be 8.1 mi (13 km).

Location

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CarriesCounty Arterial
CrossesWahluke Branch Canal
Location1.36W Columbia 416
RouteCounty Highway 4600
CountyFranklin County
StateWashington
Coordinates46.60479, -119.28997
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionDecember 2023
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourFoundations stable; scour above top of footing
Structural evaluation2: Basically intolerable, requiring high priority of replacement
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment3: Basically intolerable, requiring high priority of corrective action
Operating rating22.2 US tons
Inventory rating11.5 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans1
Design loadH 15
Structure length28 ft (8.5 m)
Longest span28 ft (8.5 m)
Deck width25 ft (7.6 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic357 (2023)
Projected traffic1,110 by 2040
Trucks37%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed8.1 mi (13 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 proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$1.4 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was County Arterial over Wahluke Branch Canal built?

It was built in 1959, making it 66 years old in 2025.

What condition is County Arterial over Wahluke Branch Canal 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 December 2023.

How much traffic does County Arterial over Wahluke Branch Canal carry?

About 357 vehicles per day (2023 count), of which roughly 37% are trucks.

How long is County Arterial over Wahluke Branch Canal?

The structure is 28 ft (8.5 m) long with a longest span of 28 ft (8.5 m) and a deck 25 ft wide.

Who owns County Arterial over Wahluke Branch Canal?

It is owned by the County Highway Agency.