US Bridges

State Route 1 over Navarro River

Good

Mendocino County, California · 01-MEN-001-40.18 · Structure no. 10 0130

Built
1949
76 years old
Condition
Good
inspected August 2024
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
478 ft
2 main spans
Daily traffic
1,100
2009 count
Owner
State
State Highway Agency

About this bridge

State Route 1 over Navarro River is a steel continuous stringer/multi-beam or girder carrying State Route 1 over Navarro River in Mendocino County, California. It was built in 1949, so it is 76 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 1,100 vehicles a day, roughly 11% of them trucks, projected to reach 2,125 by 2042. The structure is 478 ft (145.7 m) long and 32 ft wide. If it were closed, the detour would be 29.8 mi (48 km).

CarriesState Route 1
CrossesNavarro River
Location01-MEN-001-40.18
RouteState Highway 1
Coordinates39.19637, -123.74755
Functional classRural Minor Arterial

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.
Superstructure8 Very GoodNo problems noted.
Substructure7 GoodSome minor problems.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionAugust 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; action required to protect exposed foundations
Structural evaluation6: Equal to present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment4: Meets minimum tolerable limits to be left in place as is
Operating rating35.1 US tons
Inventory rating27.1 US tons

Structure

MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans2 (+3 approach)
Design loadHS 20
Structure length478 ft (145.7 m)
Longest span144 ft (43.9 m)
Deck width32 ft (9.8 m)
Roadway width26 ft (7.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,100 (2009)
Projected traffic2,125 by 2042
Trucks11%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed29.8 mi (48 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—
NavigationNavigation control on waterway (bridge permit required)

Frequently asked questions

When was State Route 1 over Navarro River built?

It was built in 1949, making it 76 years old in 2025.

What condition is State Route 1 over Navarro River 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 August 2024.

How much traffic does State Route 1 over Navarro River carry?

About 1,100 vehicles per day (2009 count), of which roughly 11% are trucks.

How long is State Route 1 over Navarro River?

The structure is 478 ft (145.7 m) long with a longest span of 144 ft (43.9 m) and a deck 32 ft wide.

Who owns State Route 1 over Navarro River?

It is owned by the State Highway Agency.