US Bridges

State Route 1 over Hillside

Fair

Mendocino County, California · 01-MEN-001-83.54 · Structure no. 10 0271

Built
1985
40 years old
Condition
Fair
inspected September 2023
Type
Box Beam or Girders - Multiple
Concrete Continuous
Length
178 ft
3 main spans
Daily traffic
1,185
2009 count
Owner
State
State Highway Agency

About this bridge

State Route 1 over Hillside is a concrete continuous box beam or girders - multiple carrying State Route 1 over Hillside in Mendocino County, California. It was built in 1985, so it is 40 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 1,185 vehicles a day, roughly 3% of them trucks, projected to reach 1,027 by 2043. The structure is 178 ft (54.3 m) long and 18 ft wide. If it were closed, the detour would be 57.8 mi (93 km).

Location

Open in Google Maps
CarriesState Route 1
CrossesHillside
Location01-MEN-001-83.54
RouteState Highway 1
CountyMendocino County
StateCalifornia
Coordinates39.71083, -123.80647
Functional classRural Minor Arterial

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.
Substructure7 GoodSome minor problems.
Last inspectionSeptember 2023
Inspection intervalevery 48 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 alignment6: Equal to present minimum criteria
Operating rating59.6 US tons
Inventory rating35.7 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20 + Mod
Structure length178 ft (54.3 m)
Longest span70 ft (21.3 m)
Deck width18 ft (5.4 m)
Roadway width32 ft (9.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,185 (2009)
Projected traffic1,027 by 2043
Trucks3%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesOther
Detour if closed57.8 mi (93 km)
TollOn a free road
National Highway SystemNo

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 1 over Hillside built?

It was built in 1985, making it 40 years old in 2025.

What condition is State Route 1 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 September 2023.

How much traffic does State Route 1 over Hillside carry?

About 1,185 vehicles per day (2009 count), of which roughly 3% are trucks.

How long is State Route 1 over Hillside?

The structure is 178 ft (54.3 m) long with a longest span of 70 ft (21.3 m) and a deck 18 ft wide.

Who owns State Route 1 over Hillside?

It is owned by the State Highway Agency.