Research was conducted to determine left-turn characteristics that would be suitable for defining a left- turn component of a signalised intersection computer simulation model. The primary characteristic studied was the left-turn gap acceptance distribution and its variation with types of left turns (non-stop or turn from waiting position) and types of gaps in the opposing traffic stream. Studies were conducted at 6 intersections in 4 large Texas cities using multiple-event recorder and 16-mm time-lapse filming techniques to develop data. Over 1000 left-turning vehicles were observed for gap acceptance and other left-turn characteristics. Gap acceptance distributions were developed on rectangular coordinates, probability-logarithmic coordinates and as regression lines on probit-log time coordinates. Chi-square tests show that there are differences in gap acceptance distributions for moving vs stopped position turns and between distributions for different types of gaps. Comparisons with more recent data from California were very favourable while other research for different left-turn situations was shown to be quite different. /author/.
Abstract