US Bridges

State Route 12 over Tylers Drainage

Good

Sonoma County, California · 04-SON-012-23.00 · Structure no. 20 0282

Built
1950
75 years old
Condition
Good
inspected September 2022
Type
Culvert
Concrete Continuous
Length
31 ft
3 main spans
Daily traffic
21,000
2016 count
Owner
State
State Highway Agency

About this bridge

State Route 12 over Tylers Drainage is a concrete continuous culvert carrying State Route 12 over Tylers Drainage in Sonoma County, California. It was built in 1950, so it is 75 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 21,000 vehicles a day, roughly 6% of them trucks, projected to reach 46,934 by 2039. The structure is 31 ft (9.6 m) long and 42 ft wide. If it were closed, the detour would be 16.8 mi (27 km).

Location

Open in Google Maps
CarriesState Route 12
CrossesTylers Drainage
Location04-SON-012-23.00
RouteState Highway 12
CountySonoma County
StateCalifornia
Coordinates38.44607, -122.60689
Functional classUrban Other Principal Arterial

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Channel and channel protection8 Very GoodNo problems noted.
Culvert7 GoodSome minor problems.
Last inspectionSeptember 2022
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation7: Better than present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating59.6 US tons
Inventory rating35.7 US tons

Structure

Structure typeCulvert
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadUnknown
Structure length31 ft (9.6 m)
Longest span11 ft (3.5 m)
Deck width42 ft (12.8 m)
Roadway width40 ft (12.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic21,000 (2016)
Projected traffic46,934 by 2039
Trucks6%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed16.8 mi (27 km)
TollOn a free road
National Highway SystemYes

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 12 over Tylers Drainage built?

It was built in 1950, making it 75 years old in 2025.

What condition is State Route 12 over Tylers Drainage 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 September 2022.

How much traffic does State Route 12 over Tylers Drainage carry?

About 21,000 vehicles per day (2016 count), of which roughly 6% are trucks.

How long is State Route 12 over Tylers Drainage?

The structure is 31 ft (9.6 m) long with a longest span of 11 ft (3.5 m) and a deck 42 ft wide.

Who owns State Route 12 over Tylers Drainage?

It is owned by the State Highway Agency.