 
Analysis  Page 2 of 2 
ID# C1040A2 
Problem 4: Analysis
The trafficactuated
timing procedure requires three control parameters.
 Minimum
phase times, considering driver expectancy and pedestrian requirements. The
minimum times from the pretimed example (Subproblem 1b)
were used here.
 Maximum
phase times to assure a reasonable distribution of green time on cycles with
heavy demand. The literature contains a variety of techniques for setting
maximum green times. For purposes of this example, the maximum green times
were set at 20% longer than the pretimed values.

Unit
extension times to determine the length of the gap in arriving traffic at
which a phase will terminate. Most traffic models, including the HCM, will
yield lower delay estimates with lower unit extension times. As a practical
constraint, however, the unit extension must be slightly longer than the
maximum expected gap between vehicles departing from a queue, otherwise
premature phase terminations will occur. For purposes of this example, the
unit extension times were set to 3 seconds for singlelane operation and
2 seconds for multiplelane operation.
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