Getting Started

Goals and Objectives
For purposes of the case study, we assume the goal is to mitigate the congestion problems. While we might also be interested in future conditions, we will focus on current conditions for the case study. The objectives are to identify the improvements in signage, geometry, and operational controls that will enhance performance.

Performance measures are related to the goals and objectives. Density is used for determining level of service (LOS) for almost all freeway facilities. Most traffic engineers use average passenger car speed as an indication of how well a facility is performing. Another performance measure is delay, which is defined here as the incremental travel time produced by the congestion present in the system. Queues are also important, although the HCM methodologies don’t provide easy ways to determine how long the queues are. Other criteria are travel times through the network, total vehicle-hours of travel, total vehicle miles, air pollution outputs, and noise impacts. For this case study, we will focus on density, speeds, and delays.