US Bridges

Main ST CR S500 over Downie River

Fair

Sierra County, California · In Downieville · Structure no. 13C0055

Built
1986
39 years old
Condition
Fair
inspected August 2023
Type
Box Beam or Girders - Single or Spread
Prestressed Concrete
Length
133 ft
1 main span
Daily traffic
150
1998 count
Owner
County
County Highway Agency

About this bridge

Main ST CR S500 over Downie River is a prestressed concrete box beam or girders - single or spread carrying Main ST CR S500 over Downie River in Sierra County, California. It was built in 1986, so it is 39 years old, younger 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 150 vehicles a day, roughly 2% of them trucks, projected to reach 207 by 2041. The structure is 133 ft (40.4 m) long and 15 ft wide. If it were closed, the detour would be 24.2 mi (39 km).

Location

Open in Google Maps
CarriesMain ST CR S500
CrossesDownie River
LocationIn Downieville
RouteCounty Highway 0
CountySierra County
StateCalifornia
Coordinates39.56968, -120.82266
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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating59.6 US tons
Inventory rating35.7 US tons

Structure

Structure typeBox Beam or Girders - Single or Spread
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20 + Mod
Structure length133 ft (40.4 m)
Longest span130 ft (39.6 m)
Deck width15 ft (4.5 m)
Roadway width14 ft (4.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic150 (1998)
Projected traffic207 by 2041
Trucks2%
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed24.2 mi (39 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 Main ST CR S500 over Downie River built?

It was built in 1986, making it 39 years old in 2025.

What condition is Main ST CR S500 over Downie River 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 Main ST CR S500 over Downie River carry?

About 150 vehicles per day (1998 count), of which roughly 2% are trucks.

How long is Main ST CR S500 over Downie River?

The structure is 133 ft (40.4 m) long with a longest span of 130 ft (39.6 m) and a deck 15 ft wide.

Who owns Main ST CR S500 over Downie River?

It is owned by the County Highway Agency.