US Bridges

Koster Road over Delta-Mendota Canal

Fair

San Joaquin County, California · 1.6 MI N Gaffery RD · Structure no. 29C0353

Built
1950
75 years old
Condition
Fair
inspected June 2024
Type
Tee Beam
Concrete
Length
105 ft
3 main spans
Daily traffic
400
2013 count
Owner
County
County Highway Agency

About this bridge

Koster Road over Delta-Mendota Canal is a concrete tee beam carrying Koster Road over Delta-Mendota Canal in San Joaquin 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 400 vehicles a day, roughly 1% of them trucks, projected to reach 348 by 2046. The structure is 105 ft (31.9 m) long and 25 ft wide. If it were closed, the detour would be 8.7 mi (14 km).

Location

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CarriesKoster Road
CrossesDelta-Mendota Canal
Location1.6 MI N Gaffery RD
RouteCounty Highway 0
CountySan Joaquin County
StateCalifornia
Coordinates37.61717, -121.32526
Functional classRural Local

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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionJune 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 geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment3: Basically intolerable, requiring high priority of corrective action
Operating rating25.4 US tons
Inventory rating19.3 US tons

Structure

Structure typeTee Beam
MaterialConcrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 15
Structure length105 ft (31.9 m)
Longest span44 ft (13.3 m)
Deck width25 ft (7.5 m)
Roadway width20 ft (6.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic400 (2013)
Projected traffic348 by 2046
Trucks1%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed8.7 mi (14 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Koster Road over Delta-Mendota Canal built?

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

What condition is Koster Road over Delta-Mendota Canal 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 June 2024.

How much traffic does Koster Road over Delta-Mendota Canal carry?

About 400 vehicles per day (2013 count), of which roughly 1% are trucks.

How long is Koster Road over Delta-Mendota Canal?

The structure is 105 ft (31.9 m) long with a longest span of 44 ft (13.3 m) and a deck 25 ft wide.

Who owns Koster Road over Delta-Mendota Canal?

It is owned by the County Highway Agency.