US Bridges

Bohan Dillon RD over South Fork Gualala River

Fair

Sonoma County, California · 0.8 MI N Fort Ross RD · Structure no. 20C0436

Built
1971
54 years old
Condition
Fair
inspected June 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
36 ft
1 main span
Daily traffic
50
2015 count
Owner
County
County Highway Agency

About this bridge

Bohan Dillon RD over South Fork Gualala River is a steel stringer/multi-beam or girder carrying Bohan Dillon RD over South Fork Gualala River in Sonoma County, California. It was built in 1971, so it is 54 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 50 vehicles a day, projected to reach 147 by 2040. The structure is 36 ft (11 m) long and 14 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

Open in Google Maps
CarriesBohan Dillon RD
CrossesSouth Fork Gualala River
Location0.8 MI N Fort Ross RD
RouteCounty Highway 0
CountySonoma County
StateCalifornia
Coordinates38.53528, -123.20121
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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
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
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
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 rating46.4 US tons
Inventory rating27.9 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckCorrugated steel
Main spans1
Design loadUnknown
Structure length36 ft (11 m)
Longest span34 ft (10.4 m)
Deck width14 ft (4.3 m)
Roadway width13 ft (4.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic50 (2015)
Projected traffic147 by 2040
Trucks—
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed123.7 mi (199 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 Bohan Dillon RD over South Fork Gualala River built?

It was built in 1971, making it 54 years old in 2025.

What condition is Bohan Dillon RD over South Fork Gualala River 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 Bohan Dillon RD over South Fork Gualala River carry?

About 50 vehicles per day (2015 count).

How long is Bohan Dillon RD over South Fork Gualala River?

The structure is 36 ft (11 m) long with a longest span of 34 ft (10.4 m) and a deck 14 ft wide.

Who owns Bohan Dillon RD over South Fork Gualala River?

It is owned by the County Highway Agency.