US Bridges

Diamond Mtn RD over Cooks Creek

Fair

Plumas County, California · 3.6 MI NE Bckwth Grnvle R · Structure no. 09C0054

Built
1950
75 years old
Condition
Fair
inspected September 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
42 ft
1 main span
Daily traffic
240
2019 count
Owner
County
County Highway Agency

About this bridge

Diamond Mtn RD over Cooks Creek is a steel stringer/multi-beam or girder carrying Diamond Mtn RD over Cooks Creek in Plumas County, California. It was built in 1950, so it is 75 years old, older than the California average of 54.8 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 5 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 240 vehicles a day, roughly 7% of them trucks, projected to reach 314 by 2044. The structure is 42 ft (12.8 m) long and 26 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

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CarriesDiamond Mtn RD
CrossesCooks Creek
Location3.6 MI NE Bckwth Grnvle R
RouteCounty Highway 0
CountyPlumas County
StateCalifornia
Coordinates40.14454, -120.81772
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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating31.7 US tons
Inventory rating19 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20 + Mod
Structure length42 ft (12.8 m)
Longest span41 ft (12.5 m)
Deck width26 ft (8 m)
Roadway width24 ft (7.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic240 (2019)
Projected traffic314 by 2044
Trucks7%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.1 mi (5 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Diamond Mtn RD over Cooks Creek built?

It was built in 1950, making it 75 years old in 2025.

What condition is Diamond Mtn RD over Cooks Creek 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 September 2023.

How much traffic does Diamond Mtn RD over Cooks Creek carry?

About 240 vehicles per day (2019 count), of which roughly 7% are trucks.

How long is Diamond Mtn RD over Cooks Creek?

The structure is 42 ft (12.8 m) long with a longest span of 41 ft (12.5 m) and a deck 26 ft wide.

Who owns Diamond Mtn RD over Cooks Creek?

It is owned by the County Highway Agency.