US Bridges

Steamboat Sl Road over Brooks Slough

Fair

Wahkiakum County, Washington · 0.1 S JCT SR 4 · Structure no. 082249000000000

Built
1959
66 years old
Condition
Fair
inspected August 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
137 ft
3 main spans
Daily traffic
187
2014 count
Owner
County
County Highway Agency

About this bridge

Steamboat Sl Road over Brooks Slough is a prestressed concrete stringer/multi-beam or girder carrying Steamboat Sl Road over Brooks Slough in Wahkiakum 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 5 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 187 vehicles a day, roughly 5% of them trucks, projected to reach 338 by 2034. The structure is 137 ft (41.8 m) long and 26 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

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CarriesSteamboat Sl Road
CrossesBrooks Slough
Location0.1 S JCT SR 4
RouteCounty Highway 92170
CountyWahkiakum County
StateWashington
Coordinates46.26908, -123.45461
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
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionAugust 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
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 rating56 US tons
Inventory rating33 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckOther
Main spans3
Design loadHS 20
Structure length137 ft (41.8 m)
Longest span72 ft (21.9 m)
Deck width26 ft (7.9 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic187 (2014)
Projected traffic338 by 2034
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed5 mi (8 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 proposedOther structural work, including hydraulic replacements
Estimated improvement cost$1.7 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Steamboat Sl Road over Brooks Slough built?

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

What condition is Steamboat Sl Road over Brooks Slough 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 Steamboat Sl Road over Brooks Slough carry?

About 187 vehicles per day (2014 count), of which roughly 5% are trucks.

How long is Steamboat Sl Road over Brooks Slough?

The structure is 137 ft (41.8 m) long with a longest span of 72 ft (21.9 m) and a deck 26 ft wide.

Who owns Steamboat Sl Road over Brooks Slough?

It is owned by the County Highway Agency.