ESTIMATION OF LEFT-TURN SATURATION FLOWS.

This paper addresses the problem of estimating left-turn saturation flows at both signalized and unsignalized intersections. The methods for estimating this traffic measure were tested for reliability against field data. A new approach to the problem is also presented. The results are applicable to left-turning traffic flowing through gaps of suitable size in the opposing traffic without the protection of a special signal phase. Both one and two lanes of opposing traffic were considered, as were unsignalized intersections. The gap-acceptance functions that best represent the behavioral patterns of left turners at these intersections are also presented. Time-lapse photography was used to collect data at five different intersections in upstate New York.