US Bridges

Mark West Sta RD over Windsor Creek

Fair

Sonoma County, California · 1.2 MI E of Tre-Healds RD · Structure no. 20C0247

Built
1976
49 years old
Condition
Fair
inspected June 2023
Type
Slab
Concrete
Length
38 ft
1 main span
Daily traffic
400
2015 count
Owner
County
County Highway Agency

About this bridge

Mark West Sta RD over Windsor Creek is a concrete slab carrying Mark West Sta RD over Windsor Creek in Sonoma County, California. It was built in 1976, so it is 49 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 5 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 400 vehicles a day, roughly 5% of them trucks, projected to reach 557 by 2040. The structure is 38 ft (11.6 m) long and 22 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

Open in Google Maps
CarriesMark West Sta RD
CrossesWindsor Creek
Location1.2 MI E of Tre-Healds RD
RouteCounty Highway 0
CountySonoma County
StateCalifornia
Coordinates38.51089, -122.84003
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.
Superstructure7 GoodSome minor problems.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection7 GoodSome minor problems.
Last inspectionJune 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy4: Meets minimum tolerable limits to be left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating57.1 US tons
Inventory rating34.3 US tons

Structure

Structure typeSlab
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length38 ft (11.6 m)
Longest span36 ft (11 m)
Deck width22 ft (6.8 m)
Roadway width22 ft (6.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic400 (2015)
Projected traffic557 by 2040
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed5 mi (8 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 Mark West Sta RD over Windsor Creek built?

It was built in 1976, making it 49 years old in 2025.

What condition is Mark West Sta RD over Windsor Creek 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 June 2023.

How much traffic does Mark West Sta RD over Windsor Creek carry?

About 400 vehicles per day (2015 count), of which roughly 5% are trucks.

How long is Mark West Sta RD over Windsor Creek?

The structure is 38 ft (11.6 m) long with a longest span of 36 ft (11 m) and a deck 22 ft wide.

Who owns Mark West Sta RD over Windsor Creek?

It is owned by the County Highway Agency.