Congestion Management Using GIS
ABRAHAM J K, EL-KHATIB N, AND DATTA T K, Wayne State University, USA
Urban congestion is a serious and worsening traffic problem that is receiving increasing attention from transportation engineers, planners and researchers. Traffic congestion is the excessive accumulation of traffic on the roadway. In the USA, completion
Urban congestion is a serious and worsening traffic problem that is receiving increasing attention from transportation engineers, planners and researchers. Traffic congestion is the excessive accumulation of traffic on the roadway. In the USA, completion of the illustrious interstate highway system is imminent today, when highway congestion has become a daily phenomenon in all large metropolitan areas and has become a source of frustration and anxiety for the millions of commuters who use the facility (Grenzeback, et al., 1992). It is reported that around 55% of urban freeway travel during the peak hour occurs under congested conditions. Over 1.2 billion vehicle-hours of delay, 1.3 billion gallons of wasted fuel and over $9 billion in user costs per year can be attributed to urban freeway congestion alone, in the USA. These costs are predicted to grow to nearly 6.8 billion vehicle hours of delay, 7.3 billion gallons of wasted fuel and over $ 450 billion of user costs by 2005. Urban freeway travel is expected to grow nearly 49% during the period from 1984 to 2005 (Sharnk, et al., 1993). Table 1 presents some costs due to traffic congestion.
There are two major types of congestion: recurring and non-recurring. Recurring congestion, is caused by too many vehicles trying to use too little roadway and normally occurs at approximately the same sections everyday. Non-recurring congestion is a temporary loss of capacity caused by an incident such as an accident, breakdown or debris on the roadway. It is reported that around 60% of all congestion is of the non- recurring type.
There have been continuous efforts to mitigate traffic congestion using various strategies including increasing capacity of the system, transportation demand management, traffic operational improvements through coordinated signals, high occupancy vehicle (HOV) lanes, access and incident management and other techniques. An organized and effective strategy employed in congestion control and efficiency of the transportation system was the passing of the 1991 Intermodal Surface Transportation Efficiency Act (ISTEA). It was signed into law by the President in December of 1991. The Act mandates that each State must develop, establish and implement six management systems. The Congestion Management System (CMS) is one of the mandated management systems concentrating on congestion control and traffic flow efficiency. The legislation calls for the renewal of surface transportation programs to address the changing needs of America. It will create jobs, reduce congestion and rebuild infrastructure.
The accurate measurement and evaluation of highway operations, performance, cost/ benefit relationships and leading trends are the key pro'cedures of all management systems included in ISTEA. They require reliable data which is expensive to collect and maintain. There is a rapid expansion however, in the availability of geographically- referenced data. This primarily due to advancements in data collection and presentation technologies, such as the Global Positioning Systems (GPS) and the Geographic Information System (GIS). This information, if properly used can enhance the benefits of location specific data. A GIS-based system is a good tool that can be used to manage and manipulate all transportation related data for the management systems.
The authors have developed such a system for a mid sized city located in the Detroit Metropolitan area in the State of Michigan, USA. The City of Novi is a northwest suburb with a population of approximately 35,000. The road network consists of freeways, arterials and local roads. They carry volumes ranging from 125,000 vehicles per day on the freeways, to 500 vehicles per day on the local residential roads.
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