Problem 2 Analysis
Problem 2: Analysis
It is now
useful to bring together the results of the three sub-problems that we
considered as part of problem 2. In this problem, we considered the
question of whether or not to signalize U.S. 95/Styner-Lauder Avenue not as an isolated one,
in which we look at only the conditions at the intersection, but rather
in the context of the U.S. 95 arterial and the intersections adjacent to Styner-Lauder.
We learned in sub-problem 2a
that the flow patterns from the adjacent intersections (specifically Sweet
Avenue) do not affect the capacity of the Styner-Lauder Avenue intersection when it
is operating with stop-sign control. The distance between Sweet Avenue
and Styner-Lauder is great enough that the platoons from Sweet Avenue have
dispersed sufficiently so that the capacities of the Styner-Lauder approaches
are not affected.
We learned in sub-problem 2b that
if the intersection of Styner-Lauder were signalized, there would be some
effect on the delay of the U.S. 95 traffic at the intersection. This
reduction in delay over the conditions that we considered in problem 1
results from the degree of coordination that can be achieved between the
Sweet Avenue and Styner-Lauder Avenue intersections.
results continue to leave open the opportunity to signalize the Styner-Lauder
We found in sub-problem 2c, however,
that when we apply the HCM urban street methodology, the benefits to the side streets (Styner
and Lauder approaches) must be traded off against a reduction in level of
service along the U.S. 95 arterial. The level of service before Styner-Lauder
is signalized is estimated to be B. After the
signal is installed, even with the seemingly acceptable delay to U.S. 95
traffic, the level of service for this arterial segment would be reduced to C,
because the travel speed on
the arterial is reduced from 29 mi/hr to 25 mi/hr.
There are other ways to minimize the impacts of a new signal on arterial
operations and the through-traffic travel times. One of these ways is to
coordinate the system of signalized intersections within the arterial
section, and the effect of this was demonstrated in sub-problem 2d.
It is also possible to minimize these impacts by restricting the
non-arterial green time at the new Styner-Lauder/U.S. 95 traffic signal. A
methodology for accomplishing this latter approach is further discussed in Problem 4.
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