US Bridges

Spring Mountain RD over Hillside

Fair

Napa County, California · 3 MI West of Madrona Ave · Structure no. 21C0131

Built
2009
16 years old
Condition
Fair
inspected May 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
61 ft
4 main spans
Daily traffic
450
2006 count
Owner
County
County Highway Agency

About this bridge

Spring Mountain RD over Hillside is a steel stringer/multi-beam or girder carrying Spring Mountain RD over Hillside in Napa County, California. It was built in 2009, so it is 16 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 450 vehicles a day, roughly 10% of them trucks, projected to reach 1,041 by 2046. The structure is 61 ft (18.6 m) long and 11 ft wide. If it were closed, the detour would be 28 mi (45 km).

Location

Open in Google Maps
CarriesSpring Mountain RD
CrossesHillside
Location3 MI West of Madrona Ave
RouteCounty Highway 0
CountyNapa County
StateCalifornia
Coordinates38.51633, -122.51726
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
Deck7 GoodSome minor problems.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionMay 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating41.8 US tons
Inventory rating25 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckCorrugated steel
Main spans4
Design loadUnknown
Structure length61 ft (18.6 m)
Longest span15 ft (4.6 m)
Deck width11 ft (3.3 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic450 (2006)
Projected traffic1,041 by 2046
Trucks10%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesOther
Detour if closed28 mi (45 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—
NavigationNot applicable (no waterway)

Frequently asked questions

When was Spring Mountain RD over Hillside built?

It was built in 2009, making it 16 years old in 2025.

What condition is Spring Mountain RD over Hillside 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 May 2024.

How much traffic does Spring Mountain RD over Hillside carry?

About 450 vehicles per day (2006 count), of which roughly 10% are trucks.

How long is Spring Mountain RD over Hillside?

The structure is 61 ft (18.6 m) long with a longest span of 15 ft (4.6 m) and a deck 11 ft wide.

Who owns Spring Mountain RD over Hillside?

It is owned by the County Highway Agency.