Sub-problem 2c: Analyzing the Effects of Coordination

One last option we might consider, since these runs have all been at a 120-second cycle, is to investigate the possibility of a shorter cycle. However, in order to maintain the ability to coordinate with the other signals along the arterial (which we are assuming to be running the 120-second cycle), we must confine our choices to only a 60-second cycle, being careful to accommodate minimum pedestrian green times as we lower the cycle length. This double-cycle option could lower delay because of the lower cycle but still maintain coordination since every other cycle will be in concert with the adjacent 120-second cycles. The results of this comparison are shown in the table below.

Comparing the results between the 120-second and 60-second cycles illustrates a couple of points. Lower cycle lengths generally result in shorter delays overall, even though capacities go down. Also, the queues are reduced substantially because the red time per phase is less, reducing the time available for queues to lengthen. This is a good strategy where storage lengths are limited, as in this problem. The overall intersection delay was reduced and queues lowered for every movement by 10% to nearly 50%. Another by-product of this strategy is that the large number of pedestrians will be given more opportunities and wait less time to cross.

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