Abstracts from the

Journal of Public Transportation

Volume 2, No. 1, 1998

Automatic Vehicle Location and Computer-Aided Dispatch Systems: Design and Application Considerations

Asad J. Khattak, University of North Carolina at Chapel Hill
Mark Hickman, Texas A&M University

Abstract

Automatic Vehicle Location (AVL) systems can track transit vehicles in real time. Computer-Aided Dispatch (CAD) software is used to monitor transit operations and assist management of transit operations. Together with AVL systems, CAD software can be used to replace a disabled vehicle by dispatching another vehicle, or meet fluctuating travel demand by adjusting transit headways, schedules, and routes. AVL and CAD technologies can vitalize transit by directly improving on-time performance, increasing transit efficiency through providing dispatchers with location, direction and status information, and reducing operating costs through reducing dependence on transit field supervisory personnel. Direct benefits to travelers can include higher reliability of travel times and reduced stress in dealing with transit unreliability. This study explores the development, availability, and impacts of AVL/CAD technologies as reported by AVL vendors and transit implementers. The study defines the key features, functions, and performance characteristics of AVL/CAD technologies that can influence the level of benefits realized. The AVL/CAD implementation context is explored by examining where, when, and for what users these systems are being implemented. The results of two surveys are reported. To explore the availability of AVL/CAD systems, technology suppliers were surveyed. Suppliers identified the features, functions, and performance of available AVL/CAD technologies. To determine the extent of AVL/CAD deployment, transit operators were surveyed regarding their experiences with AVL/CAD technologies and the subsequent impacts on travelers and transit agency performance. This research provides a systematic method for evaluation of AVL/CAD systems and reports the perceptions of AVL/CAD vendors and transit implementers regarding available products and their impacts. The results suggest a need for better tools to characterize and quantify the impacts and benefits of AVL/CAD systems.

A Strategic Approach to the Transportation Planning Process

Edward A. Mierzejewski
University of South Florida

Abstract

The underlying premise of the urban transportation planning process is that we can forecast the future. The process typically develops 20-year forecasts of traffic volumes on each link of the transportation network. Planners then attempt to devise a master plan that represents an optimal solution for the forecasted conditions. The reality is that we cannot predict the future. Imponderable and unpredictable events will shape the future in ways we cannot hope to anticipate. In addition, social and political bias is a strong contributor to errors in anticipating future events and to our willingness to deal with uncertainty. This paper identifies possible remedies for dealing with uncertainty and bias, including better analytical methods, better process methods, and methods to counter bias. An evaluation of various remedies is performed and practical measures that can be applied to the urban transportation planning process are identified. Finally, specific recommended modifications to the urban transportation planning process are outlined.

Transit-Oriented Development Suitability Analysis by the Analytic Hierarchy Process and a Geographic Information System: A Prototype Procedure

Reza Banai, The University of Memphis

Abstract

A prototype procedure is illustrated to assess the suitability of land use around proposed light rail transit stations of a metropolitan area, with an example of a focus on one station area land use pattern. Transit oriented development (TOD) guidelines provide the criteria for an assessment. The procedure for assessment is facilitated by a geographic information system (GIS), and the Analytic Hierarchy Process (AHP), a multicriteria methodology that is increasingly employed in conjunction with geographic information systems. The weights of the criteria are determined through paired comparisons (relative measurement), and a ratings intensity scale is used to determine the scores of land units (absolute measurement). This flexibility in measurement is helpful in situations where land use criteria, such as TOD guidelines, as suitability factors and with certain desirable thresholds of intensity are known, but must be considered strategically and adaptively, responsive to local priorities and site-specific conditions. The scores of land uses on a scale of zero to 100 percent are determined, which indicate the degrees of the suitability of a transit station area as a potential TOD. As well, the proportions suggest changes that target particular parcels--individually and as a group--so as to bring about a desirable mix of the public, core/employment, and housing uses for an urban TOD. This prototype application highlights the versatile properties of the AHP, particularly when used in the specific context of a development paradigm (TOD) in conjunction with a geographic information system that has not been previously addressed in the literature on applications.

Perceived Service Quality Attributes in Public Transport: Inferences from Complaints and Negative Critical Incidents

Margareta Friman, University of Karlstad, Sweden
Bo Edvardsson, University of Karlstad, Sweden
Tommy Gärling, Göteborg University, Sweden

Abstract

A sample of 200 complaints filed to a public transport company and 210 negative critical incidents (NCIs) obtained from on-board interviews were analyzed with the purpose of inferring perceived service quality (PSQ) attributes of public transport. The most frequent complaints and NCIs concerned employee behavior and punctuality, followed by missing or inaccurate information and inadequate planning. In a follow-up mail survey, a representative sample of 997 respondents reported if they remembered having experienced prototypical NCIs constructed on the basis of the complaints. Confirming the validity of the inferred PSQ attributes, all NCIs were reported to have been experienced by at least some respondents. NCIs related to employee behavior were, however, less frequently remembered, whereas those related to vehicle design and space, punctuality, and traffic planning were more frequently re membered. Taken together, the results suggest that PSQ attributes in public transport refer to employee behavior, reliability, and simplicity. Finally, inferences made from customer complaints and negative critical incidents are shown to extend our knowledge of perceived service quality attributes in public transport.

The Value of Having a Public Transit Travel Choice

Xuehao Chu, University of South Florida
Steven E. Polzin, University of South Florida

Abstract

The value of having a public transit travel choice is occasionally acknowledged by planners but never quantified; this paper provides a methodology to quantify it. This value of having a public transit choice is in addition to public transit's benefits to users and non-users as a result of the improved performance of other modes in the transportation system resulting from the public transit investment. The value of choice accrues to the total population that has access to public transit, not just those who chose to use it or those who benefit because others have chosen it. This paper develops a methodology and a crude but plausible estimate of the value of choice for public transit using data describing features of U.S. daily personal travel in 1995. For perspective, this estimate is compared with the total operating and capital expense of providing public transit in the United States. The result indicates that the value of choice alone is comparable in magnitude to the cost of providing public transit in this country.