Showing papers on "Intelligent transportation system published in 1973"

Merge control in automated transit system networks

Abstract: Many small vehicle automated transit system concepts will require vehicles to negotiate intersections and merge with other vehicles while traveling through a network of guideways. Assuming that the longitudinal control of vehicles is accomplished by what is known as the moving-cell or point-follower approach, the merge control problem becomes one of determining necessary point-skip maneuvers to assure that points equi-distant from a merge junction are not simultaneously occupied by vehicles. This paper describes an original algorithm for intersection control which can satisfactorily resolve such merge conflicts 95 percent of the time for system traffic densities approaching 80 percent of capacity by monitoring the status of only twelve points on each line. The algorithm is suitable for programming in a small digital computer; one of which is conceptually located at each intersection.

Safety Analysis for Automated Transportation Systems

Abstract: This paper outlines an approach to analyzing the safety characteristics of vehicular ground transportation systems operated under computer surveillance and control. A quantitative index of safety is formulated, and a procedure is developed for analyzing the dependence of system safety on the significant design parameters and performance attributes. Lower bounds on the permissible minimum headway are established on the assumption of instantaneous and perfect control, so that the effects of various sensing, communication, control and actuation subsystems can be assessed independently. Time delays in emergency control—resulting from discrete sensor spacing, finite sampling time, and loss of telemetered data—are analyzed and expressions for the attendant increase in the minimum headway are developed. The general approach and the specific techniques are illustrated with numerical examples.

On the operation of automated ground transportation systems, part I: Urban problems and perspectives

Abstract: Several approaches to the operation of automated ground transport systems for urban use are presented and evaluated. Such systems have been suggested principally in response to the problems of urban traffic congestian and are often proposed as solutions to such problems. Thus this paper, the first of a series of three, discusses the problems of urban transportation and their origins, identifying as the principal elements the institutional structure, urban geography, and design of facilities for urban automotive transport. Importantly, the origins of a significant portion of "the urban transportation problem" lie outside the transport sector. Six potential applications for automated transport systems are suggested, ranging from specialized single-link "horizontal elevators" to general-purpose wide-area networks.

Hsgt as an operating problem

Abstract: Too much attention has been paid to the technical aspects of high-speed guided systems when operational differences may be even more important. In particular, it appears to be impossible for vehicles which cannot be coupled into trains to carry sufficient passengers to pay for the track on which they run. Switch design is also critical, and the author explains what effect speed restrictions imposed by switching have on journey time and the pattern of service offered.

Review of technical and operational aspects of several fixed-guideway public transportation systems

Abstract: The purpose of this paper is to review the major technical and operational characteristics of several contemporary fixed-guideway public transportation systems and to determine the functional distinctions among them. Six systems are compared with respect to the following characteristics: nature of the vehicle-guideway interface, station layout, vehicle spacing control, general operating specifications, and specifications for nominal levels of vehicle performance. The 6 systems considered range from urban rail transit systems to monorail systems. Although they are unlike one another in many respects, they nonetheless function in much the same manner when contrasted to personal rapid transit systems currently being developed.