PL PACKET 09191995 - Laserfiche WebLink

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CHAPTER 4 TRANSPORTATION 75 • 2. Interrupted Flow — (Signalized Intersections) The level of service for signalized intersections is quantified by use of a term called "loaded cycle." A signal or phase is considered to be "loaded" if vehicles arriving on any approach, having stopped for a red indication, fail to clear the signal on the next green indication. At level of service A, there are no loaded cycles. At level of service B, an occasional signal phase is fully utilized and platoons may begin to form. At level of service C, most drivers are beginning to feel some restriction, but not to an objectionable degree. At level of service D, excessive backups are avoided only because occasional periods of low demand allow the signals to catch up and clear out developing queues. At level of service E, capacity is reached. Delays may exceed several signal cycles. At level of service F, all approaches to the signal are jammed. Backups from • intersections beyond may prevent vehicles from clearing the intersections. 3. Design Capacity Level.of service C is generally used to establish design parameters. Corresponding traffic volume figures for various situations are: Freeways — 1350 vehicles per lane per hour. Signalized 4-Lane Arterials — total of 1500 vehicles per hour on the arterial with a moderate amount of cross traffic from the side street. Four Way Stop (two lane by two lane intersection) — maximum total of 1900 vehicles per hour for all four approaches. ANALYSIS OF YEAR 2000 LEVEL OF SERVICE METHODOLOGY By comparing future travel demand with the capacity of the existing roadway system it can be determined where increased capacity may be needed to maintain "C" level of service.