Roundabout Design Blue Lake Roundabout One of the many roundabout designs completed by W-Trans was constructed at the intersection of Blue Lake Boulevard and Chartin Way in county of Humboldt in August of 2002. The intersection serves as the gateway to the City of Blue Lake, a small rural community about 8 miles east of Humboldt Bay. The design process included field testing and consideration for the lumber trucks that periodically travel through the intersection and previously entered the town at high speeds. This design process resulted in a truck apron which was wider and more shallow than typically used in order to serve extended, low-bed vehicles which travel to the neighboring lumber mill. Civil engineering for the project was completed by Oscar Larson & Associates of Eureka. View Project Photo Gallery Corona Road/Sonoma Mountain Parkway W-Trans provided analysis, conceptual design and final design of the second major roundabout in the City of Petaluma. Construction is anticipated to begin in the Spring of 2003. Casa Grande Road/Ely Boulevard South Roundabout Allan Tilton participated in the planning, design review and development oversight of two roundabouts on collector streets while serving as Petaluma's City Traffic Engineer. These roundabouts were installed in 1998 and have the distinction of being the first roundabouts in Sonoma County and the North Bay. They have served as models and have been visited often by other North Bay agencies. Lucky Drive/Doherty Drive Roundabout (Larkspur, California) W-Trans continues work on a roundabout design for an intersection that provides access to Redwood High School along a primary arterial in the City of Larkspur. The roundabout is expected to be particularly effective at this location because the arterial has a right-angle turn at the intersection, with the school driveway and a recreational trail forming the remaining two legs. Healdsburg Avenue/Vine Street/Mill Street W-Trans prepared a feasibility study and developed a conceptual design for a single lane roundabout at the intersection of Healdsburg Avenue-Vine Street/Mill Street. This 5-legged intersection is currently signalized, with NWPRR tracks running diagonally across it, resulting in operation that is confusing to the unfamiliar driver such as the substantial number of tourists in the City of Healdsburg. Consideration was given to truck movements as well as the need to control traffic during activity along the currently inactive rail line. The City has folded action on this proposal into a larger "Entryways" project as it improves operation and has the potential to provide a more aesthetic entry to the downtown area. Old Redwood Highway/Henry Street As part of the "Walkable Cotati" design process, W-Trans designed a downtown gateway roundabout. During the design process, a field test of fire truck maneuverability was demonstrated to the local fire district. The completion of the roundabout will be considered as part of a secondary phase of the downtown streetscape project. State Route 12/Napa Road-Leveroni Road W-Trans designed a roundabout for the "four corners" area which is intended to be a gateway element for the City of Sonoma. Coordination and Facilitation for Design of a Four-Roundabout "Ring Junction" W-Trans developed a concept incorporating four roundabouts that would replace one large signalized intersection at the hub of the City of Cotati. The new circulation scheme would allow the City to reunite its La Plaza Park by closing the existing signalized intersection. As part of the process, a simulation of the circulation was developed using SimTraffic. Gilman Street Interchange W-Trans authored a draft Project Study Report that evaluated roundabout intersections at the Gilman Street interchange with I-80 in the City of Berkeley. Each roundabout would combine the freeway on and off ramps as well as the adjacent frontage road with Gilman Street, transforming the interchange which currently consists of a pair of two closely spaced intersections into a pair of roundabouts. Schematic roundabout designs for the two intersections were presented in the document. Planning and coordination with Caltrans and the City of Berkeley continues. Sebastopol Intersection Comparative Analysis W-Trans completed a comparative analysis of alternative intersection traffic control treatments including roundabouts and traffic signals at several intersections in the City of Sebastopol. The comparison considered quantifiable measures such as intersection level of service, delay and vehicle speeds and more qualitative measures such as availability of space, vehicular safety, pedestrian safety, bicycle safety, parking impacts, queuing and urban design appeal. U.S. 101/S.R. 20 W-Trans evaluated the potential operation of a roundabout on U.S. 101 in comparison with existing traffic signal control. Indian Hill Boulevard Roundabouts W-Trans developed a circulation scheme incorporating three consecutive roundabout controlled intersections for the purposes of accommodating development of an abandoned warehouse district and encouraging interaction between the two sides of this City of Claremont boulevard. As a demonstration project, W-Trans designed a temporary roundabout installation at one of the locations which the City installed. It should be noted that the City eventually removed the installation due to mixed public opinion on the benefits of the temporary installation.

© 2003 Whitlock & Weinberger Transportation, Inc.