ESTIMATING THE BENEFITS OF MOBILITY ENHANCEMENTS AT THE AREAWIDE LEVEL

For many years, the Texas Transportation Institute (TTI) has released a study of macroscopic traffic congestion levels in urban areas across the United States. This analysis has been based solely on a traffic density analysis without regard to mobility enhancements such as ramp metering or traffic signal coordination that might have been implemented to aid in peak period movement. Many transportation agencies have spent a great deal of their resources in recent years to implement Intelligent Transportation System treatments and programs to improve mobility and reliability that do not change daily traffic volumes. These treatments may improve peak operations and increase throughput but get overlooked in the historical TTI congestion analysis. In order to show a more accurate picture of urban congestion, a new methodology has been developed at TTI to incorporate the effects of several of these treatments or programs into the macroscopic mobility performance measures. The mobility treatments and programs discussed include: (1) freeway incident management; (2) freeway entrance ramp metering; (3) arterial signal coordination; (4) high-occupancy vehicle lanes; and (5) public transportation. This new methodology utilizes simplistic information such as delay reduction percentages associated with each treatment type to provide a planning-level benefits analysis of the effects of many of these mobility enhancing techniques. The effects of high-occupancy vehicle lanes and public transportation are analyzed by shifting these respective passengers back into automobiles on the roadway system. This paper discusses the methods used to calculate the benefits from each of these techniques and shows these calculated benefits.