Problem 4 - Page 1 of 1
Problem 4: Analysis of the
Alternate Route 7 Freeway Facility
In the previous three problems of this case
study, we examined the operation of individual segments of Alternate Route 7,
including basic freeway segments, weaving sections, and ramp junctions. In
this problem, we will step back and consider the segments as drivers actually
see them: part of a complete freeway facility. This perspective is also the way
that the New York State DOT views this facility, a facility operating as a whole
unit rather than separate components.
In addition, there are interactions between
the various segments of this freeway that we have previously studied. For
example, we earlier considered the weaving section that exists on eastbound
Alternate Route 7 between the I-87 NB on-ramp and the U.S. Route 9 off-ramp on the
western portion of the facility. A weaving section is by its nature a
combination of two ramp junctions. Another example of the interaction
between segments is when the flows from one part of the freeway interact with
the flows from another part of the freeway. If a bottleneck exists, say as
a result of a temporary lane closure, the flow from the bottleneck may spill
back a mile or more upstream.
The question that we consider in this
problem is how to determine the performance of the facility as a whole,
then use this analysis to help us to identify (or verify) problems that exist in
the field today.
We will consider three sub-problems to
illustrate the application of the freeway facility analysis procedure.
Sub-problem 4a - How
should the Alternate
Route 7 facility be divided up for an HCM operational analysis?
Sub-problem 4b - What is
the operational performance of Alternate Route 7 during the off peak period?
Sub-problem 4c - What is the operational
performance of Alternate Route 7 during the peak period?
Continue with sub-problem 4a when you are ready.
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