US Bridges

I-5 over Np RY & Dillenbaugh CR

Fair

Lewis County, Washington · 6.1 N JCT SR 508 · Structure no. 0012597A0000000

Built
1954
71 years old, rebuilt 1986
Condition
Fair
inspected July 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
537 ft
1 main span
Daily traffic
36,296
2023 count
Owner
State
State Highway Agency

About this bridge

I-5 over Np RY & Dillenbaugh CR is a steel stringer/multi-beam or girder carrying I-5 over Np RY & Dillenbaugh CR in Lewis County, Washington. It was built in 1954 and reconstructed in 1986, so it is 71 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 36,296 vehicles a day, roughly 21% of them trucks, projected to reach 47,507 by 2039. The structure is 537 ft (163.7 m) long and 85 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

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CarriesI-5
CrossesNp RY & Dillenbaugh CR
Location6.1 N JCT SR 508
RouteInterstate 5
CountyLewis County
StateWashington
Coordinates46.65086, -122.96925
Functional classUrban Principal Arterial - Interstate

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.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionJuly 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Deck geometry9: Superior to present desirable criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating47 US tons
Inventory rating30 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1 (+8 approach)
Design loadHS 20 + Mod
Structure length537 ft (163.7 m)
Longest span93 ft (28.3 m)
Deck width85 ft (25.8 m)
Roadway width81 ft (24.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic36,296 (2023)
Projected traffic47,507 by 2039
Trucks21%
Lanes on structure4
Traffic directionOne-way traffic
CarriesHighway
CrossesRailroad and waterway
Detour if closed1.9 mi (3 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

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$11.2 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was I-5 over Np RY & Dillenbaugh CR built?

It was built in 1954, making it 71 years old in 2025. It was reconstructed in 1986.

What condition is I-5 over Np RY & Dillenbaugh CR 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 July 2024.

How much traffic does I-5 over Np RY & Dillenbaugh CR carry?

About 36,296 vehicles per day (2023 count), of which roughly 21% are trucks.

How long is I-5 over Np RY & Dillenbaugh CR?

The structure is 537 ft (163.7 m) long with a longest span of 93 ft (28.3 m) and a deck 85 ft wide.

Who owns I-5 over Np RY & Dillenbaugh CR?

It is owned by the State Highway Agency.