US Bridges

CO RD 56 over Alturas Creek

Fair

Modoc County, California · 0.50 MI E/O US 395 · Structure no. 03C0111

Built
1938
87 years old
Condition
Fair
inspected August 2023
Type
Culvert
Concrete Continuous
Length
22 ft
3 main spans
Daily traffic
800
2012 count
Owner
County
County Highway Agency

About this bridge

CO RD 56 over Alturas Creek is a concrete continuous culvert carrying CO RD 56 over Alturas Creek in Modoc County, California. It was built in 1938, so it is 87 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 800 vehicles a day, roughly 7% of them trucks, projected to reach 943 by 2041. The structure is 22 ft (6.7 m) long. If it were closed, the detour would be 9.9 mi (16 km).

Location

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CarriesCO RD 56
CrossesAlturas Creek
Location0.50 MI E/O US 395
RouteCounty Highway 0
CountyModoc County
StateCalifornia
Coordinates41.47994, -120.53221
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
Channel and channel protection7 GoodSome minor problems.
Culvert5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
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
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating44.6 US tons
Inventory rating26.8 US tons

Structure

Structure typeCulvert
MaterialConcrete Continuous
DeckNot applicable
Main spans3
Design loadUnknown
Structure length22 ft (6.7 m)
Longest span8 ft (2.4 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic800 (2012)
Projected traffic943 by 2041
Trucks7%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed9.9 mi (16 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 CO RD 56 over Alturas Creek built?

It was built in 1938, making it 87 years old in 2025.

What condition is CO RD 56 over Alturas 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 August 2023.

How much traffic does CO RD 56 over Alturas Creek carry?

About 800 vehicles per day (2012 count), of which roughly 7% are trucks.

How long is CO RD 56 over Alturas Creek?

The structure is 22 ft (6.7 m) long with a longest span of 8 ft (2.4 m).

Who owns CO RD 56 over Alturas Creek?

It is owned by the County Highway Agency.