SR 05:276 - Laserfiche WebLink

Vineyard Avenue Roundabouts In July of 2001, City Council approved the design and construction of two roundabouts on Vineyard Avenue adjacent to the Neal School site. The Vineyard Avenue Corridor Specific Plan included a new traffic signal on Vineyard Avenue at its intersection with the collector road on the west side of the future school site. However, because most of the students projected to attend this school lived in Ruby Hill, the school site was designed such that the primary drop-off zones and school packing lot entrances were off of the collector street on the east side of the school. The west side of the school was designed for limited student drop off and the end of the street was designed to accommodate a bus turnaround on this lower volume roadway. Because of the layout of the school, the plan was to construct a traffic signal at the east school side street instead of the west school side street. City Staff used traffic simulation models to analyze circulation around the school during the morning peak hour. All traffic simulations indicated that the combination of morning commuter and school traffic would create very bad LOS F conditions at this intersection with a traffic back-up that would extend beyond the fire station. In the Specific Plan, Vineyard Avenue was to be built as a 2-lane rural roadway. There was a drainage culvert just east of this intersection that limited how long the left turn pocket could be for traffic waiting to turn onto the east school side street. Double left turn lanes are usually needed as traffic volumes approach 300 vehicles per hour. At this intersection, left turn volumes are expected to exceed 500 vehicles per hour, and these vehicles will all want to make their left turns in about a 15-minute period. At the same time, after dropping their students off, about this same amount of traffic will try to exit the school site. A single left turn lane 75 feet long was not adequate to handle this traffic, so all left turn and through traffic congested the one eastbound lane with left turns blocking through traffic and through traffic blocking left turners. During this same time period, staff was designing the roundabouts for Valley Avenue south of Bernal Avenue as part of the Bernal Properties specific plan. The federal design guidelines indicated that a roundabout designed like the ones on Valley A venue would handle traffic volumes on Vineyard Avenue near Neal School better than a traffic signal could. The roundabouts would work well on a 2-lane road and would not be affected by the proximity of the drainage culvert. Computer simulations of the roundabouts indicated that the continuous traffic flow around the roundabout would minimize any traffic back-ups east of the school. In addition, roundabouts would slow traffic adjacent to an elementary school being built along a 50 MPH roadway. Staff prepared computer simulations of both the double roundabout design and the traffic signal and presented them to the Ruby Hill Homeowners Association, the Fire Chief, the School District and some Vineyard Avenue residents. The consensus was that between the two options, the roundabouts were preferred, especially as they improved emergency access along Vineyard A venue from the Fire Station. SR:05:276 Page 4 of9