US Bridges

Diamond Mtn RD over Lights Creek

Fair

Plumas County, California · 4.9 MI NE Grnvle-Beck RD · Structure no. 09C0044

Built
1956
69 years old
Condition
Fair
inspected September 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
103 ft
2 main spans
Daily traffic
70
2019 count
Owner
County
County Highway Agency

About this bridge

Diamond Mtn RD over Lights Creek is a steel stringer/multi-beam or girder carrying Diamond Mtn RD over Lights Creek in Plumas County, California. It was built in 1956, so it is 69 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 70 vehicles a day, roughly 7% of them trucks, projected to reach 180 by 2041. The structure is 103 ft (31.4 m) long and 26 ft wide. If it were closed, the detour would be 11.8 mi (19 km).

Location

Open in Google Maps
CarriesDiamond Mtn RD
CrossesLights Creek
Location4.9 MI NE Grnvle-Beck RD
RouteCounty Highway 0
CountyPlumas County
StateCalifornia
Coordinates40.15003, -120.79513
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
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating107.8 US tons
Inventory rating64.6 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans2
Design loadH 20
Structure length103 ft (31.4 m)
Longest span50 ft (15.2 m)
Deck width26 ft (8 m)
Roadway width26 ft (7.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic70 (2019)
Projected traffic180 by 2041
Trucks7%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed11.8 mi (19 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 Lights Creek built?

It was built in 1956, making it 69 years old in 2025.

What condition is Diamond Mtn RD over Lights 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 Lights Creek carry?

About 70 vehicles per day (2019 count), of which roughly 7% are trucks.

How long is Diamond Mtn RD over Lights Creek?

The structure is 103 ft (31.4 m) long with a longest span of 50 ft (15.2 m) and a deck 26 ft wide.

Who owns Diamond Mtn RD over Lights Creek?

It is owned by the County Highway Agency.