US Bridges

SR 506 over Stillwater CR

Good

Lewis County, Washington · 3.7 E Cowlitz CO · Structure no. 0007158A0000000

Built
1963
62 years old
Condition
Good
inspected September 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
200 ft
3 main spans
Daily traffic
994
2023 count
Owner
State
State Highway Agency

About this bridge

SR 506 over Stillwater CR is a prestressed concrete stringer/multi-beam or girder carrying SR 506 over Stillwater CR in Lewis County, Washington. It was built in 1963, so it is 62 years old, older than the Washington average of 49.8 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 994 vehicles a day, roughly 12% of them trucks, projected to reach 1,130 by 2039. The structure is 200 ft (61 m) long and 31 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

Open in Google Maps
CarriesSR 506
CrossesStillwater CR
Location3.7 E Cowlitz CO
RouteState Highway 506
CountyLewis County
StateWashington
Coordinates46.40956, -122.98714
Functional classRural Major Collector

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck8 Very GoodNo problems noted.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionSeptember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation7: Better than 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 rating65 US tons
Inventory rating39 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length200 ft (61 m)
Longest span99 ft (30.2 m)
Deck width31 ft (9.6 m)
Roadway width26 ft (7.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic994 (2023)
Projected traffic1,130 by 2039
Trucks12%
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

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$2.9 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SR 506 over Stillwater CR built?

It was built in 1963, making it 62 years old in 2025.

What condition is SR 506 over Stillwater CR in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in September 2024.

How much traffic does SR 506 over Stillwater CR carry?

About 994 vehicles per day (2023 count), of which roughly 12% are trucks.

How long is SR 506 over Stillwater CR?

The structure is 200 ft (61 m) long with a longest span of 99 ft (30.2 m) and a deck 31 ft wide.

Who owns SR 506 over Stillwater CR?

It is owned by the State Highway Agency.