US Bridges

Old Redwood HWY over Mark West Creek

Fair

Sonoma County, California · 0.4 MI S/O Airport Blvd · Structure no. 20C0083

Built
1956
69 years old
Condition
Fair
inspected June 2023
Type
Slab
Concrete Continuous
Length
173 ft
6 main spans
Daily traffic
16,600
2015 count
Owner
County
County Highway Agency

About this bridge

Old Redwood HWY over Mark West Creek is a concrete continuous slab carrying Old Redwood HWY over Mark West Creek in Sonoma County, California. It was built in 1956, so it is 69 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 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 16,600 vehicles a day, roughly 2% of them trucks, projected to reach 8,523 by 2040. The structure is 173 ft (52.7 m) long and 37 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

Open in Google Maps
CarriesOld Redwood HWY
CrossesMark West Creek
Location0.4 MI S/O Airport Blvd
RouteCounty Highway 0
CountySonoma County
StateCalifornia
Coordinates38.50626, -122.75898
Functional classUrban 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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure7 GoodSome minor problems.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
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 geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating54.2 US tons
Inventory rating32.8 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans6
Design loadHS 20
Structure length173 ft (52.7 m)
Longest span31 ft (9.4 m)
Deck width37 ft (11.2 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic16,600 (2015)
Projected traffic8,523 by 2040
Trucks2%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
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 Old Redwood HWY over Mark West Creek built?

It was built in 1956, making it 69 years old in 2025.

What condition is Old Redwood HWY over Mark West 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 Old Redwood HWY over Mark West Creek carry?

About 16,600 vehicles per day (2015 count), of which roughly 2% are trucks.

How long is Old Redwood HWY over Mark West Creek?

The structure is 173 ft (52.7 m) long with a longest span of 31 ft (9.4 m) and a deck 37 ft wide.

Who owns Old Redwood HWY over Mark West Creek?

It is owned by the County Highway Agency.