This project will construct a single-lane roundabout at the intersection of Las Positas Road at Cliff Drive in order to improve traffic operations by reducing congestion and recurrent queuing currently experienced at the intersection, particularly during the evening commute hours. The roundabout incorporates bicycle and pedestrian facilities and will allow for future connectivity to a proposed multiuse pathway along Las Positas Road and bike lanes and/or bike path along Cliff Drive. The overall size of the roundabout has been minimized as much as possible, while still maintaining adequate access for trucks and buses.
The roundabout will include eight new streetlights on the roadway approaches and at the roundabout itself. Early design concepts included nearly twice that many lights, but given the natural context of the area, the minimum amount of lighting required for safety is proposed. The three existing lights will be removed. The new lights will be mounted at a height of approximately 20-feet, which is lower than the existing lights. This will minimize light trespass into the neighborhood and natural areas, while providing sufficient lighting levels for the roundabout.
To improve pedestrian safety at Alan Road, a raised median refuge island is planned (approximately the same location as the existing painted median). The drawings for the median refuge island are not yet complete, but the island will be built at the same time as the roundabout.
After receiving direction from City Council to proceed with the design and construction of a roundabout at this location in January 2014, staff contracted with Kittelson & Associates, a consulting firm specializing in roundabouts, to complete the roundabout design. The project is currently at 30% design and is undergoing environmental and design review. Staff anticipates presenting the current design plans to the Architectural Board of Review (ABR) for concept review on October 12, 2015. Construction is anticipated to begin in fall 2016.