US Bridges

Geysers RD over Big Sulphur Creek

Fair

Sonoma County, California · 18.6 MI N of SH 128 · Structure no. 20C0005

Built
1909
116 years old
Condition
Fair
inspected July 2023
Type
Truss - Thru
Steel
Length
150 ft
1 main span
Daily traffic
140
2008 count
Owner
County
County Highway Agency

About this bridge

Geysers RD over Big Sulphur Creek is a steel truss - thru carrying Geysers RD over Big Sulphur Creek in Sonoma County, California. It was built in 1909, so it is 116 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 140 vehicles a day, roughly 10% of them trucks, projected to reach 458 by 2043. The structure is 150 ft (45.8 m) long and 14 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

Open in Google Maps
CarriesGeysers RD
CrossesBig Sulphur Creek
Location18.6 MI N of SH 128
RouteCounty Highway 0
CountySonoma County
StateCalifornia
Coordinates38.82353, -122.88336
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.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
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 inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourUnknown foundation; not evaluated for scour
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 adequacy7: Better than present minimum criteria
Approach roadway alignment3: Basically intolerable, requiring high priority of corrective action
Operating rating64.3 US tons
Inventory rating38.6 US tons

Structure

Structure typeTruss - Thru
MaterialSteel
DeckCorrugated steel
Main spans1 (+1 approach)
Design loadUnknown
Structure length150 ft (45.8 m)
Longest span130 ft (39.7 m)
Deck width14 ft (4.3 m)
Roadway width13 ft (4.1 m)
Vertical clearance over deck21 ft (6.5 m)

Traffic and service

Average daily traffic140 (2008)
Projected traffic458 by 2043
Trucks10%
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 statusEligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Geysers RD over Big Sulphur Creek built?

It was built in 1909, making it 116 years old in 2025.

What condition is Geysers RD over Big Sulphur 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 July 2023.

How much traffic does Geysers RD over Big Sulphur Creek carry?

About 140 vehicles per day (2008 count), of which roughly 10% are trucks.

How long is Geysers RD over Big Sulphur Creek?

The structure is 150 ft (45.8 m) long with a longest span of 130 ft (39.7 m) and a deck 14 ft wide.

Who owns Geysers RD over Big Sulphur Creek?

It is owned by the County Highway Agency.