US Bridges

SR 507 over Skookumchuck River

Poor

Lewis County, Washington · 2.4 N JCT I-5 · Structure no. 000000HV0000000

Built
1928
97 years old
Condition
Poor
inspected June 2023
Type
Truss - Thru
Steel
Length
186 ft
1 main span
Daily traffic
8,908
2023 count
Owner
State
State Highway Agency

About this bridge

SR 507 over Skookumchuck River is a steel truss - thru carrying SR 507 over Skookumchuck River in Lewis County, Washington. It was built in 1928, so it is 97 years old, older than the Washington average of 49.8 years.

The most recent inspection reported to the Federal Highway Administration rates it in poor condition with a lowest component rating of 4 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

It carries about 8,908 vehicles a day, roughly 5% of them trucks, projected to reach 11,640 by 2039. The structure is 186 ft (56.7 m) long and 22 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

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CarriesSR 507
CrossesSkookumchuck River
Location2.4 N JCT I-5
RouteState Highway 507
CountyLewis County
StateWashington
Coordinates46.73042, -122.95369
Functional classUrban Minor Arterial

Condition and inspection

Poor

The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure4 PoorAdvanced section loss, deterioration, spalling or scour.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection7 GoodSome minor problems.
Last inspectionJune 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating41 US tons
Inventory rating25 US tons

Structure

Structure typeTruss - Thru
MaterialSteel
DeckConcrete, cast-in-place
Main spans1 (+2 approach)
Design loadH 20
Structure length186 ft (56.7 m)
Longest span149 ft (45.4 m)
Deck width22 ft (6.7 m)
Roadway width20 ft (6.1 m)
Vertical clearance over deck15 ft (4.5 m)

Traffic and service

Average daily traffic8,908 (2023)
Projected traffic11,640 by 2039
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed3.7 mi (6 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusPossibly eligible for the National Register; requires further investigation
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$3 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SR 507 over Skookumchuck River built?

It was built in 1928, making it 97 years old in 2025.

What condition is SR 507 over Skookumchuck River in?

The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in June 2023.

How much traffic does SR 507 over Skookumchuck River carry?

About 8,908 vehicles per day (2023 count), of which roughly 5% are trucks.

How long is SR 507 over Skookumchuck River?

The structure is 186 ft (56.7 m) long with a longest span of 149 ft (45.4 m) and a deck 22 ft wide.

Who owns SR 507 over Skookumchuck River?

It is owned by the State Highway Agency.