Innovations in Actuated Signalized Diamond Interchange Control
Author(s):
C.J. Messer
Publication Date:
October 1983
Abstract:
The operational features of three-phase and four-phase diamond interchange signal control are evaluated in this paper. Site characteristics, data collection methods, and procedures employed for the study are described. General descriptions are presented of the traffic volumes, cycle lengths, traffic delays, and queue characteristics observed for three-phase and four-phase control at four diamond interchanges. An assessment of traffic signal phasing is described in terms of operational effects on queues, cycle lengths, and multistops. It was concluded from the traffic studied and for the operational environment experienced that three-phase control, in general, resulted in less delay, fewer stopped vehicles and shorter cycle lengths than four-phase control for a given traffic volume. Further, the characteristics of queue, traffic volume, and three- and four-phase control may not be appropriate under certain interchange geometrics and traffic conditions. Specifically, three-phase control may not be proper for those interchanges having extremely short distances between signals and no separate left-turn bays between signals. Similarly, four-phase control may not be appropriate for those interchanges which are located short distances away from freeway exit and entrance ramps.
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