US Bridges

Diablo Camp Road over Diablo Tailrace

FairClosed to traffic

King County, Washington · Diablo Powerhouse · Structure no. 087459000000000

Built
1962
63 years old
Condition
Fair
inspected December 2022
Type
Girder and Floorbeam System
Steel
Length
112 ft
2 main spans
Daily traffic
205
2022 count
Owner
Local
Other Local Agency

About this bridge

Diablo Camp Road over Diablo Tailrace is a steel girder and floorbeam system carrying Diablo Camp Road over Diablo Tailrace in King County, Washington. It was built in 1962, so it is 63 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. Its operating status is: closed to all traffic.

It carries about 205 vehicles a day, roughly 15% of them trucks, projected to reach 215 by 2042. The structure is 112 ft (34.1 m) long and 16 ft wide.

Location

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CarriesDiablo Camp Road
CrossesDiablo Tailrace
LocationDiablo Powerhouse
CountyKing County
StateWashington
Coordinates48.71578, -121.14181
Functional classRural Minor 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.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionDecember 2022
Inspection intervalevery 24 months
Operating statusClosed to all traffic
ScourScour evaluation has not been made
Structural evaluation6: Equal to present minimum criteria
Deck geometry0: Immediate repair necessary to put back in service
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating62.8 US tons
Inventory rating48.6 US tons

Structure

Structure typeGirder and Floorbeam System
MaterialSteel
DeckOpen grating
Main spans2
Design loadUnknown
Structure length112 ft (34.1 m)
Longest span52 ft (15.8 m)
Deck width16 ft (4.9 m)
Roadway width15 ft (4.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic205 (2022)
Projected traffic215 by 2042
Trucks15%
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed—
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerOther Local Agency
Maintained byOther Local Agency
Historic statusHistorical significance not determinable at this time
Work proposedDeck rehabilitation with only incidental widening
Estimated improvement cost$904,000 (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Diablo Camp Road over Diablo Tailrace built?

It was built in 1962, making it 63 years old in 2025.

What condition is Diablo Camp Road over Diablo Tailrace 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 December 2022.

How much traffic does Diablo Camp Road over Diablo Tailrace carry?

About 205 vehicles per day (2022 count), of which roughly 15% are trucks.

How long is Diablo Camp Road over Diablo Tailrace?

The structure is 112 ft (34.1 m) long with a longest span of 52 ft (15.8 m) and a deck 16 ft wide.

Who owns Diablo Camp Road over Diablo Tailrace?

It is owned by the Other Local Agency.