Getting Started

Sequencing, Tools, and Data
Sequencing the analyses is another issue. We’re going to focus on the signalized intersections first, starting at Maxwell Drive (Intersection C), working west to Intersections B and A, then east to Intersections D and G (see Exhibit 2-1). This allows us to study the most affected intersection first, then ones that are less affected because they are further away. We’ll consider the freeway interchange after we’ve finished with the signalized intersections, then we will analyze the arterial segment consisting of intersections A to D.

Choosing the tools to use is another issue. You have to pick ones that strike a balance between the amount of effort they require and the amount of insight they provide. In this case study, we’re going to use two tools. The first is the Highway Capacity Manual. We’ll use it for all of the intersection analyses and the location-specific analyses at the freeway interchange. The second is Transyt-7F. We’ll use it to do an arterial analysis of intersections A through D. It will help us ascertain what coordinated signal timings would work best for that set of signals. It should be emphasized that we are using Transyt-7F here to illustrate the use of non-HCM procedures, and other programs could also be used with equal effectiveness.

Since the main purpose of this guidebook is to illustrate how the HCM can be used to study traffic issues, we’ll use this tool wherever possible. We’ll also show where it isn’t applicable, explain why, and illustrate how other non-HCM tools can be used.