US Bridges

Old Monte Rio Road over Hillside

Fair

Sonoma County, California · 0.6 Mile S SR 116 · Structure no. 20C0508

Built
1996
29 years old
Condition
Fair
inspected November 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
75 ft
4 main spans
Daily traffic
100
2015 count
Owner
County
County Highway Agency

About this bridge

Old Monte Rio Road over Hillside is a steel stringer/multi-beam or girder carrying Old Monte Rio Road over Hillside in Sonoma County, California. It was built in 1996, so it is 29 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 100 vehicles a day, roughly 1% of them trucks, projected to reach 217 by 2042. The structure is 75 ft (23 m) long and 10 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesOld Monte Rio Road
CrossesHillside
Location0.6 Mile S SR 116
RouteCounty Highway 0
CountySonoma County
StateCalifornia
Coordinates38.49132, -123.01652
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionNovember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating47.5 US tons
Inventory rating28.2 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckCorrugated steel
Main spans4
Design loadHS 20 + Mod
Structure length75 ft (23 m)
Longest span20 ft (6 m)
Deck width10 ft (3.1 m)
Roadway width21 ft (6.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic100 (2015)
Projected traffic217 by 2042
Trucks1%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesOther
Detour if closed1.2 mi (2 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 Old Monte Rio Road over Hillside built?

It was built in 1996, making it 29 years old in 2025.

What condition is Old Monte Rio 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 November 2024.

How much traffic does Old Monte Rio Road over Hillside carry?

About 100 vehicles per day (2015 count), of which roughly 1% are trucks.

How long is Old Monte Rio Road over Hillside?

The structure is 75 ft (23 m) long with a longest span of 20 ft (6 m) and a deck 10 ft wide.

Who owns Old Monte Rio Road over Hillside?

It is owned by the County Highway Agency.