Getting Started

What Analyses to Perform
In this case study, we need to examine the basic freeway sections on Alternate Route 7 and the interchanges at either end. We should study these in every time period, although the most crucial period is when the facility use is at its peak. We might also want to do a system-level analysis to ensure that we have accounted for all the impacts that arise. We’ll try to answer these questions as the case study proceeds.

Regarding the interchange-level analyses, there are 40 ramps in the network: five interchanges with eight ramps each (consisting of left- and right-hand ramps for each directional approach). If we consider the AM and PM peaks, plus directional analyses on Alternate Route 7, we would do 84 separate analyses.

Rather than presenting that many analyses, we will focus on specific problems to illustrate how to use the HCM. These problems are listed in Exhibit 4-4. For each, we’ve identified the situation to be analyzed (e.g., the school complex entrance during the AM peak) and the learning objectives and analysis issues that will be highlighted by that problem. The learning objectives are grouped into three stages: setting up the problem, doing the analysis, and results interpretation. The issues break into scope (e.g., geographic boundaries, time periods), demands (e.g., demand vs. volume), and geometrics.