US Bridges

State Route 20 over Slacks Ravine

Fair

Nevada County, California · 03-NEV-020-R1.37 · Structure no. 17 0105

Built
2008
17 years old
Condition
Fair
inspected July 2024
Type
Box Beam or Girders - Single or Spread
Prestressed Concrete Continuous
Length
208 ft
3 main spans
Daily traffic
8,200
2020 count
Owner
State
State Highway Agency

About this bridge

State Route 20 over Slacks Ravine is a prestressed concrete continuous box beam or girders - single or spread carrying State Route 20 over Slacks Ravine in Nevada County, California. It was built in 2008, so it is 17 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 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 8,200 vehicles a day, roughly 5% of them trucks, projected to reach 14,378 by 2041. The structure is 208 ft (63.3 m) long and 42 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

Open in Google Maps
CarriesState Route 20
CrossesSlacks Ravine
Location03-NEV-020-R1.37
RouteState Highway 20
CountyNevada County
StateCalifornia
Coordinates39.2069, -121.25856
Functional classRural Principal Arterial - Other

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.
Superstructure8 Very GoodNo problems noted.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionJuly 2024
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating59.6 US tons
Inventory rating35.7 US tons

Structure

Structure typeBox Beam or Girders - Single or Spread
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20 + Mod
Structure length208 ft (63.3 m)
Longest span84 ft (25.6 m)
Deck width42 ft (12.9 m)
Roadway width39 ft (12 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic8,200 (2020)
Projected traffic14,378 by 2041
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed5 mi (8 km)
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNot applicable (no waterway)

Frequently asked questions

When was State Route 20 over Slacks Ravine built?

It was built in 2008, making it 17 years old in 2025.

What condition is State Route 20 over Slacks Ravine 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 July 2024.

How much traffic does State Route 20 over Slacks Ravine carry?

About 8,200 vehicles per day (2020 count), of which roughly 5% are trucks.

How long is State Route 20 over Slacks Ravine?

The structure is 208 ft (63.3 m) long with a longest span of 84 ft (25.6 m) and a deck 42 ft wide.

Who owns State Route 20 over Slacks Ravine?

It is owned by the State Highway Agency.