7A, Planning Case 11-011 – Select Senior Living PUD & Plat

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(HCM). The procedures describe operating conditions in terms of a Level of Service (LOS). Facilities are given letter designations from “A,” representing the best operating conditions, to “F,” representing the worst. Generally, Level of Service “D” represents the threshold for acceptable overall intersection operating conditions during a peak hour. The acceptable threshold for a particular movement at an intersection depends on both the priority assigned to that movement and its traffic volume. In general, the higher the priority and the higher the traffic volume, the more stringent the acceptable threshold will be. For example, the acceptable threshold for a high-priority/high-volume suburban movement might be “C,” while LOS “F” on a low-priority/low- volume urban movement might be appropriate. For side-street stop-controlled intersections, a key measure of operational effectiveness is the side-street LOS. Long delays and poor LOS can sometimes result on the side street, even if the overall intersection is functioning well, making it a valuable design criterion. Again, depending on priority and traffic volume, acceptable side-street LOS can range from “D” to “F.” A final fundamental component of operational analyses is a study of vehicular queuing, or the lineup of vehicles waiting to pass through an intersection. An intersection can operate with an acceptable level of service, but if queues from the intersection extend back to block entrances to turn lanes or accesses to th adjacent land uses, unsafe operating conditions could result. The 95 percentile queue, or the length of queue with a 5% chance of occurring during the peak hour, is considered the standard for design purposes. To assess the background traffic conditions, RLK used the Existing PM Peak Hour Traffic Volumes that 2 were recorded in the Traffic Impact Study developed as part of the Guiding Plan for the B2 District. Access Considerations Due to access management considerations along County Road E, access to the development parcels has been limited to three driveways. The westerly site driveway is approximately 975 feet west of Lexington Avenue. The central driveway for pick-up/drop-off access to the front of the senior center is approximately 775 feet west of Lexington. The proposed driveway accessing the east side of the senior center and the conceptual parcel is approximately 425 feet west of Lexington. The City of Arden Hills has recommended an eastbound one-way traffic flow for the pick-up/drop-off traffic at the front of the senior center. In other words, traffic would enter only at the driveway 775 feet west of Lexington. After pick-up and drop-off, this traffic would join the other site traffic at the eastern driveway 425 feet west of Lexington. Both the eastern driveway and the western driveway would be full access driveways. The City has recommended that traffic once on the site at the easterly driveway be restricted to turning right only toward the east side of the senior center and the conceptual parcel. This traffic would not be allowed to turn left toward the pick-up/drop-off drive. RLK tested the impacts of this alignment, as well as a westbound pick-up/drop-off drive between the easterly and central driveways onto County Road E (discussed later). 2 Traffic Impact Study, Guiding Plan for the B2 District, Arden Hills, MN, prepared by Spack Consulting, December 5, 2008. Page 5 of 7 June 6, 2011 RLK Incorporated Co. Rd. E & Lexington Traffic Study 2011-052-M