This paper describes a large experiment done in Santiago, Chile, in order to calibrate the PICADY 2 program for estimating capacity and delay of priority junctions so that it could be used in local conditions. The problem mainly consisted of determining the regression coefficient P(i), and Q(o) as the function of junction geometry. P(i) indicates the magnitude of the interrelation between the priority links and the non priority links, and Q(o), the theoretical saturation flow of the non priority link if the disturbing priority link flows are zero. Various types of intersection were studied: (i) non priority right turning approach; (ii) non priority left turning approach; and (iii) non priority left turning approach with encountered flow. Measurements of traffic flows and queues were made by video filming in peak periods. The junctions used were all at least 250 metres away from traffic signal junctions. In all, 18 junctions were selected. Surveillance produced records of 43 different situations with a total of 1059 useful observations. The data were processed using the SAS statistical package and analyzed using non linear regression (NLIN). The results indicate that the parameters obtained in the Chilean experiments were of the same order of magnitude as the British figures. Permission is being sought to include these parameters in PICADY 2.
Abstract