US Bridges

Forest Avenue over Sydney Gulch

Fair

Trinity County, California · 0.2 MI South of SR 299 · Structure no. 05C0102

Built
1949
76 years old
Condition
Fair
inspected August 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
28 ft
1 main span
Daily traffic
1,946
2010 count
Owner
County
County Highway Agency

About this bridge

Forest Avenue over Sydney Gulch is a steel stringer/multi-beam or girder carrying Forest Avenue over Sydney Gulch in Trinity County, California. It was built in 1949, so it is 76 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 1,946 vehicles a day, roughly 2% of them trucks, projected to reach 2,085 by 2042. The structure is 28 ft (8.5 m) long and 36 ft wide. If it were closed, the detour would be 0.6 mi (1 km).

Location

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CarriesForest Avenue
CrossesSydney Gulch
Location0.2 MI South of SR 299
RouteCounty Highway 0
CountyTrinity County
StateCalifornia
Coordinates40.73387, -122.9424
Functional classRural Major 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 protection8 Very GoodNo problems noted.
Last inspectionAugust 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 adequacy8: Equal to present desirable criteria
Approach roadway alignment3: Basically intolerable, requiring high priority of corrective action
Operating rating43.2 US tons
Inventory rating26.1 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadUnknown
Structure length28 ft (8.5 m)
Longest span26 ft (7.9 m)
Deck width36 ft (11.1 m)
Roadway width34 ft (10.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,946 (2010)
Projected traffic2,085 by 2042
Trucks2%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed0.6 mi (1 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 Forest Avenue over Sydney Gulch built?

It was built in 1949, making it 76 years old in 2025.

What condition is Forest Avenue over Sydney Gulch 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 August 2023.

How much traffic does Forest Avenue over Sydney Gulch carry?

About 1,946 vehicles per day (2010 count), of which roughly 2% are trucks.

How long is Forest Avenue over Sydney Gulch?

The structure is 28 ft (8.5 m) long with a longest span of 26 ft (7.9 m) and a deck 36 ft wide.

Who owns Forest Avenue over Sydney Gulch?

It is owned by the County Highway Agency.