US Bridges

ST Helena Road over Hillside

Fair

Sonoma County, California · 4.3 MI E/O Calistoga RD · Structure no. 20C0547

Built
2007
18 years old
Condition
Fair
inspected October 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
30 ft
1 main span
Daily traffic
2,100
2015 count
Owner
County
County Highway Agency

About this bridge

ST Helena Road over Hillside is a steel stringer/multi-beam or girder carrying ST Helena Road over Hillside in Sonoma County, California. It was built in 2007, so it is 18 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 2,100 vehicles a day, roughly 2% of them trucks, projected to reach 3,280 by 2046. The structure is 30 ft (9.1 m) long and 7 ft wide. If it were closed, the detour would be 37.3 mi (60 km).

Location

Open in Google Maps
CarriesST Helena Road
CrossesHillside
Location4.3 MI E/O Calistoga RD
RouteCounty Highway 0
CountySonoma County
StateCalifornia
Coordinates38.51819, -122.58697
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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionOctober 2024
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry2: Basically intolerable, requiring high priority of replacement
Approach roadway alignment8: Equal to present desirable criteria
Operating rating81.8 US tons
Inventory rating48.9 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckCorrugated steel
Main spans1
Design loadUnknown
Structure length30 ft (9.1 m)
Longest span29 ft (8.7 m)
Deck width7 ft (2 m)
Roadway width25 ft (7.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,100 (2015)
Projected traffic3,280 by 2046
Trucks2%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesOther
Detour if closed37.3 mi (60 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 ST Helena Road over Hillside built?

It was built in 2007, making it 18 years old in 2025.

What condition is ST Helena Road 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 October 2024.

How much traffic does ST Helena Road over Hillside carry?

About 2,100 vehicles per day (2015 count), of which roughly 2% are trucks.

How long is ST Helena Road over Hillside?

The structure is 30 ft (9.1 m) long with a longest span of 29 ft (8.7 m) and a deck 7 ft wide.

Who owns ST Helena Road over Hillside?

It is owned by the County Highway Agency.