US Bridges

State Route 20 over SR 174 (colfax) Auburn

Good

Nevada County, California · 03-NEV-020-R12.85-GVY · Structure no. 17 0050

Built
1970
55 years old
Condition
Good
inspected July 2024
Type
Box Beam or Girders - Multiple
Concrete Continuous
Length
477 ft
7 main spans
Daily traffic
43,000
2009 count
Owner
State
State Highway Agency

About this bridge

State Route 20 over SR 174 (colfax) Auburn is a concrete continuous box beam or girders - multiple carrying State Route 20 over SR 174 (colfax) Auburn in Nevada County, California. It was built in 1970, so it is 55 years old, older than the California average of 54.8 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 43,000 vehicles a day, roughly 7% of them trucks, projected to reach 75,938 by 2046. The structure is 477 ft (145.4 m) long and 74 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesState Route 20
CrossesSR 174 (colfax) Auburn
Location03-NEV-020-R12.85-GVY
RouteState Highway 20
CountyNevada County
StateCalifornia
Coordinates39.21572, -121.06188
Functional classUrban Principal Arterial - Other Freeway or Expressway

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Last inspectionJuly 2024
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation7: Better than present minimum criteria
Deck geometry7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating70.8 US tons
Inventory rating42.5 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans7
Design loadHS 20
Structure length477 ft (145.4 m)
Longest span93 ft (28.3 m)
Deck width74 ft (22.6 m)
Roadway width69 ft (21 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic43,000 (2009)
Projected traffic75,938 by 2046
Trucks7%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesHighway
CrossesHighway
Detour if closed1.2 mi (2 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 SR 174 (colfax) Auburn built?

It was built in 1970, making it 55 years old in 2025.

What condition is State Route 20 over SR 174 (colfax) Auburn in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in July 2024.

How much traffic does State Route 20 over SR 174 (colfax) Auburn carry?

About 43,000 vehicles per day (2009 count), of which roughly 7% are trucks.

How long is State Route 20 over SR 174 (colfax) Auburn?

The structure is 477 ft (145.4 m) long with a longest span of 93 ft (28.3 m) and a deck 74 ft wide.

Who owns State Route 20 over SR 174 (colfax) Auburn?

It is owned by the State Highway Agency.