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C. All-Way Stop Controlled Intersections <br /> There is no accepted procedure for a level of service analysis of an all-way stop <br /> controlled intersection. The procedure used for determining LOS for a four-way or <br /> three-way stop controlled intersection differs from that described for unsignalized <br /> intersections. This methodology, which is being reviewed by the Unsignalized <br /> Intersection Committee of the-'Transportation research Board, used a capacity <br /> estimation method based on headways observed at all-way stop controlled intersections <br /> in the western United States. The procedures incorporate several important variables, <br /> including volumes distribution,number of lanes on each approach, and the percentage <br /> of right and left turns at the intersection. Intersection performance is measured in <br /> parameters similar to signalized intersections: delay, volume/capacity ratio, and level <br /> of service using a scale of "A" throegh "F". Approach delay on any given leg of the <br /> intersection is calculated using the following equation: <br /> D=exp(3.8x(SV-i-C)) <br /> Where D = vehicle delay on a given approach(sec/veh) <br /> SV = subject approach volume (vph) <br /> C = calculated approach capacity (vph) <br /> exp = base of natural logarithms <br /> In this equation, the quantity SV/C is simply the volume-to-capacity ratio on the <br /> approach under consideration. Table E-5 presents the LOS criteria for all-way stop <br /> controlled intersections. <br /> E-2 <br />