HCMAG -- Case Study 2 -- Route 146 Corridor
Introduction, and Getting Started Printable Version
This case study is about a
Traffic Impact Assessment for a proposed site development in Clifton Park,
New York (see Exhibit
2-1). The large parcel of land in question is south of where Maxwell Drive
intersects with Clifton Park Boulevard (State Route 146). Like most impact
assessments, the main question is this: in the horizon year for the
analysis, what geometric improvements will be required to mitigate the
impacts of the site development in conjunction with normal traffic growth?
The Town of Clifton Park and New York
State Department of Transportation (NYSDOT) both have roles to play in the
decision-making. So do Saratoga County, the town’s citizens, the
nearby land owners, and the developer. There are issues about how many
intersections should be studied, what time periods should be examined,
what goals and objectives should be used, and what performance measures
should be employed.
To address these issues and others, the
case study includes six problems. They range in scope from a single
intersection to a sub-area network. Each one illustrates some aspect of the
impact assessment. Each one also illustrates how various traffic analysis
tools in the
Highway Capacity Manual can be applied to
assist traffic analysts, engineers, planners, and decision-makers in making
sound investment decisions regarding changes to a transportation system.
The problems focus on the chapters of the
HCM that deal with interrupted flow facilities, especially signalized
intersections, arterials, freeway interchanges, and arterial weaving. After studying this material, you should be able to:
the operation of signalized intersections, unsignalized intersections,
and urban arterials using the HCM.
what input data are required and the assumptions that are commonly
made regarding default values for the HCM procedures for these
the appropriate kinds of analysis that should be undertaken for existing
facilities as well facilities or conditions in the future, including the
scope of the
the limitations of the HCM procedures and when it is appropriate to
use other models or computational tools.
how to reasonably interpret the results from an HCM analysis and how
these results can be used to support a particular decision regarding a
change to a transportation system.