Problem 4: Analysis of the Alternate Route 7 Freeway Facility

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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.