US Bridges

Adobe RD over Lynch Creek

Fair

Sonoma County, California · 3.2 MI S Petaluma Hill RD · Structure no. 20C0205

Built
1950
75 years old, rebuilt 1963
Condition
Fair
inspected April 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
29 ft
1 main span
Daily traffic
11,600
2015 count
Owner
County
County Highway Agency

About this bridge

Adobe RD over Lynch Creek is a steel stringer/multi-beam or girder carrying Adobe RD over Lynch Creek in Sonoma County, California. It was built in 1950 and reconstructed in 1963, 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 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 11,600 vehicles a day, roughly 5% of them trucks, projected to reach 14,486 by 2046. The structure is 29 ft (8.8 m) long and 38 ft wide. If it were closed, the detour would be 6.8 mi (11 km).

Location

Open in Google Maps
CarriesAdobe RD
CrossesLynch Creek
Location3.2 MI S Petaluma Hill RD
RouteCounty Highway 0
CountySonoma County
StateCalifornia
Coordinates38.27468, -122.61919
Functional classRural 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
Deck7 GoodSome minor problems.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure7 GoodSome minor problems.
Channel and channel protection9 ExcellentNo problems noted.
Last inspectionApril 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating35.4 US tons
Inventory rating21.1 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadUnknown
Structure length29 ft (8.8 m)
Longest span27 ft (8.3 m)
Deck width38 ft (11.6 m)
Roadway width37 ft (11.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic11,600 (2015)
Projected traffic14,486 by 2046
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.8 mi (11 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 Adobe RD over Lynch Creek built?

It was built in 1950, making it 75 years old in 2025. It was reconstructed in 1963.

What condition is Adobe RD over Lynch 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 April 2024.

How much traffic does Adobe RD over Lynch Creek carry?

About 11,600 vehicles per day (2015 count), of which roughly 5% are trucks.

How long is Adobe RD over Lynch Creek?

The structure is 29 ft (8.8 m) long with a longest span of 27 ft (8.3 m) and a deck 38 ft wide.

Who owns Adobe RD over Lynch Creek?

It is owned by the County Highway Agency.