US Bridges

SR 508 over Tilton River

Fair

Lewis County, Washington · 32.4 E JCT I-5 · Structure no. 0003305A0000000

Built
1947
78 years old
Condition
Fair
inspected February 2024
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
201 ft
2 main spans
Daily traffic
2,232
2023 count
Owner
State
State Highway Agency

About this bridge

SR 508 over Tilton River is a steel continuous stringer/multi-beam or girder carrying SR 508 over Tilton River in Lewis County, Washington. It was built in 1947, so it is 78 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.

It carries about 2,232 vehicles a day, roughly 9% of them trucks, projected to reach 2,766 by 2039. The structure is 201 ft (61.3 m) long and 30 ft wide. If it were closed, the detour would be 34.8 mi (56 km).

Location

Open in Google Maps
CarriesSR 508
CrossesTilton River
Location32.4 E JCT I-5
RouteState Highway 508
CountyLewis County
StateWashington
Coordinates46.56087, -122.28544
Functional classRural Major 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.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection4 PoorAdvanced section loss, deterioration, spalling or scour.
Last inspectionFebruary 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourCountermeasures installed to correct a previously existing problem
Structural evaluation6: Equal to present minimum criteria
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 rating52 US tons
Inventory rating31 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans2 (+1 approach)
Design loadHS 15
Structure length201 ft (61.3 m)
Longest span100 ft (30.5 m)
Deck width30 ft (9.1 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,232 (2023)
Projected traffic2,766 by 2039
Trucks9%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed34.8 mi (56 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$3.1 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SR 508 over Tilton River built?

It was built in 1947, making it 78 years old in 2025.

What condition is SR 508 over Tilton River 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 February 2024.

How much traffic does SR 508 over Tilton River carry?

About 2,232 vehicles per day (2023 count), of which roughly 9% are trucks.

How long is SR 508 over Tilton River?

The structure is 201 ft (61.3 m) long with a longest span of 100 ft (30.5 m) and a deck 30 ft wide.

Who owns SR 508 over Tilton River?

It is owned by the State Highway Agency.