How to cross the historic Geysers Road Bridge in California?
Located in Sonoma County, in the U.S. state of California, the Geysers Road Bridge is a historic pin-connected iron Pratt truss bridge supported by Phoenix columns. Spanning 45.25 meters (148.47 ft) over Big Sulphur Creek near Cloverdale, it carries the paved mountain stretch of Geysers Road through the Mayacamas Mountains.
| Bridge facts: Geysers Road Bridge | |
|---|---|
| Location | Cloverdale, Sonoma County, California (USA) |
| Carries | Geysers Road |
| Crosses | Big Sulphur Creek |
| Length | 45.25 m (148.47 ft) |
| Structure Type | Iron Pratt through truss with Phoenix columns |
| Original Erection / Relocation | Erected in 1909, relocated to current site in 1937 |
| Lanes / Width | Single lane (one-lane bottleneck) |
Where is the Geysers Road Bridge located?
The bridge stands along Geysers Road near Cloverdale in northern Sonoma County, California. It crosses Big Sulphur Creek in a remote canyon within the Mayacamas Mountains, serving as a single-lane crossing along the route leading toward The Geysers geothermal field.
When was the Geysers Road Bridge built?
The iron structure was originally fabricated and erected in 1909 at another location. In 1937, county engineers dismantled and relocated the bridge to its current site across Big Sulphur Creek to carry Geysers Road traffic. An official historic sign posted at the bridge portal documents its 1909 construction and 1937 relocation dates.
What are the structural features of the Geysers Road Bridge?
The structure is built using Phoenix columns—patented hollow wrought-iron cylindrical posts made of riveted segments that were widely used in late 19th and early 20th-century bridge construction. The single-span Pratt through-truss design features overhead bracing members, rust-patinated iron girders, wooden deck planking, and narrow steel guardrails running along the interior single-lane deck.
Is the Geysers Road Bridge dangerous to cross?
The main hazard is the narrow single-lane clearance combined with blind approach angles. Driving off the approach onto the bridge requires dropping speed significantly to align with the narrow iron portal. Vehicles must yield to oncoming traffic before entering, as two cars cannot pass inside the truss superstructure. Heavy trucks face strict weight and clearance limits due to the age of the historic iron frame.
Why is the Geysers Road Bridge famous?
It ranks among the few surviving pin-connected Phoenix column truss bridges still active on a public roadway in Northern California, securing its place on the list of the most spectacular bridges in the world for historic industrial architecture.