US Bridges

Westside RD over Norton Slough

Fair

Sonoma County, California · W of SR 101 at Healdsbrg · Structure no. 20C0061

Built
1960
65 years old
Condition
Fair
inspected October 2024
Type
Slab
Concrete Continuous
Length
82 ft
3 main spans
Daily traffic
6,100
2015 count
Owner
County
County Highway Agency

About this bridge

Westside RD over Norton Slough is a concrete continuous slab carrying Westside RD over Norton Slough in Sonoma County, California. It was built in 1960, so it is 65 years old, older 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 6,100 vehicles a day, roughly 2% of them trucks, projected to reach 7,237 by 2046. The structure is 82 ft (25.1 m) long and 46 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

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CarriesWestside RD
CrossesNorton Slough
LocationW of SR 101 at Healdsbrg
RouteCounty Highway 0
CountySonoma County
StateCalifornia
Coordinates38.60686, -122.87432
Functional classRural Major Collector

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.
Substructure8 Very GoodNo problems noted.
Channel and channel protection7 GoodSome minor problems.
Last inspectionOctober 2024
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating72.1 US tons
Inventory rating43.2 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20 + Mod
Structure length82 ft (25.1 m)
Longest span32 ft (9.8 m)
Deck width46 ft (14 m)
Roadway width40 ft (12.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic6,100 (2015)
Projected traffic7,237 by 2046
Trucks2%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.1 mi (5 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—
NavigationNo navigation control on waterway

Frequently asked questions

When was Westside RD over Norton Slough built?

It was built in 1960, making it 65 years old in 2025.

What condition is Westside RD over Norton Slough 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 Westside RD over Norton Slough carry?

About 6,100 vehicles per day (2015 count), of which roughly 2% are trucks.

How long is Westside RD over Norton Slough?

The structure is 82 ft (25.1 m) long with a longest span of 32 ft (9.8 m) and a deck 46 ft wide.

Who owns Westside RD over Norton Slough?

It is owned by the County Highway Agency.