US Bridges

South Fork Road over Big Creek

Fair

Trinity County, California · 4.8 MI N Hyampom RD · Structure no. 05C0123

Built
1940
85 years old, rebuilt 1992
Condition
Fair
inspected May 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
40 ft
1 main span
Daily traffic
160
2000 count
Owner
County
County Highway Agency

About this bridge

South Fork Road over Big Creek is a steel stringer/multi-beam or girder carrying South Fork Road over Big Creek in Trinity County, California. It was built in 1940 and reconstructed in 1992, so it is 85 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 160 vehicles a day, roughly 4% of them trucks, projected to reach 212 by 2042. The structure is 40 ft (12.2 m) long and 28 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

Open in Google Maps
CarriesSouth Fork Road
CrossesBig Creek
Location4.8 MI N Hyampom RD
RouteCounty Highway 0
CountyTrinity County
StateCalifornia
Coordinates40.64598, -123.49443
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.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionMay 2024
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 adequacy9: Superior to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating43.5 US tons
Inventory rating26.1 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckCorrugated steel
Main spans1
Design loadUnknown
Structure length40 ft (12.2 m)
Longest span38 ft (11.6 m)
Deck width28 ft (8.5 m)
Roadway width27 ft (8.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic160 (2000)
Projected traffic212 by 2042
Trucks4%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed123.7 mi (199 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 South Fork Road over Big Creek built?

It was built in 1940, making it 85 years old in 2025. It was reconstructed in 1992.

What condition is South Fork Road over Big 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 May 2024.

How much traffic does South Fork Road over Big Creek carry?

About 160 vehicles per day (2000 count), of which roughly 4% are trucks.

How long is South Fork Road over Big Creek?

The structure is 40 ft (12.2 m) long with a longest span of 38 ft (11.6 m) and a deck 28 ft wide.

Who owns South Fork Road over Big Creek?

It is owned by the County Highway Agency.