Arnold Drive at Agua Caliente Road Roundabout

This project was to improve traffic safety for all modes of travel through this intersection. This was the first of several roundabout projects the County had constructed. The County evaluated the feasibility of a traffic roundabout in addition to a signalization project and the roundabout option resulted in the removal of fewer trees, less right-of-way, lower vehicle emissions, less noise and no impact to three creek crossings.

The Department proceeded with the single lane roundabout design. It is important to note that there is a strong endorsement by the U.S. Department of Transportation and the Federal Highway Administration which have issued a national goal of 10,000 new roundabouts throughout the country.

Project improvements consisted of a single lane roundabout with pedestrian sidewalks, bike lanes, drainage facilities, lighting, signage, architectural hardscape treatments, center-island retaining structure, bolder enhancements and landscaping.

CALTROP provided resident engineering, inspection and office engineering services.

LOCATION: Sonoma County, CA
CLIENT: Sonoma County
CONTRACT VALUE: $2 million


  • Heavy Traffic Conditions
  • High Risk Utilities
  • Architectural Enhancements


  • Resident Engineering
  • Inspection
  • Office Engineering
  • Public Outreach