US Bridges

Triangle Road over Summit Creek

Fair

Mariposa County, California · State Route 140 · Structure no. 40C0065

Built
1935
90 years old
Condition
Fair
inspected September 2023
Type
Culvert
Concrete Continuous
Length
31 ft
3 main spans
Daily traffic
960
1988 count
Owner
County
County Highway Agency

About this bridge

Triangle Road over Summit Creek is a concrete continuous culvert carrying Triangle Road over Summit Creek in Mariposa County, California. It was built in 1935, so it is 90 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 6 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 960 vehicles a day, roughly 3% of them trucks, projected to reach 2,137 by 2040. The structure is 31 ft (9.6 m) long and 29 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesTriangle Road
CrossesSummit Creek
LocationState Route 140
RouteCounty Highway 0
CountyMariposa County
StateCalifornia
Coordinates37.52403, -119.92138
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
Channel and channel protection7 GoodSome minor problems.
Culvert6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation4: Meets minimum tolerable limits to be 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 alignment8: Equal to present desirable criteria
Operating rating30 US tons
Inventory rating17.9 US tons

Structure

Structure typeCulvert
MaterialConcrete Continuous
DeckNot applicable
Main spans3
Design loadUnknown
Structure length31 ft (9.6 m)
Longest span10 ft (3 m)
Deck width29 ft (8.7 m)
Roadway width27 ft (8.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic960 (1988)
Projected traffic2,137 by 2040
Trucks3%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 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 Triangle Road over Summit Creek built?

It was built in 1935, making it 90 years old in 2025.

What condition is Triangle Road over Summit 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 Triangle Road over Summit Creek carry?

About 960 vehicles per day (1988 count), of which roughly 3% are trucks.

How long is Triangle Road over Summit Creek?

The structure is 31 ft (9.6 m) long with a longest span of 10 ft (3 m) and a deck 29 ft wide.

Who owns Triangle Road over Summit Creek?

It is owned by the County Highway Agency.