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A vehicle waiting at an intersection with a major road makes a merging maneuver into the mainstream traffic, thus possibly requiring oncoming traffic to slow down. This paper examines the resulting disturbance that this forced entry may create in the main stream, assumed to be a renewal process. After showing that the disturbance propagation is formally equivalent to the busy period of a related queuing model, explicit results on the length of disturbance period and the number of vehicles affected are obtained for the case of Poisson traffic. It is shown that there is some minimal main-stream headway which should be forced in order to maximize the rate at which entries can be made from the secondary road. Finally, two measures of accident potential for the merging maneuver are discussed. [ABSTRACT FROM AUTHOR]

The longitudinal vehicle control problem associated with any automated transportation scheme is discussed. The two fundamental aspects of the problem are the logical aspect and the control aspect. The logical aspect of the problem concerns the decision of where vehicles should be at a future time, based on present system conditions, so that the level of service delivered by the system is good. The control aspect is concerned with how to control vehicles to attain and maintain their desired positions while giving a comfortable ride, not taking too long, not exceeding car capabilities, and maintaining safety. Previous work dealing with both the logical and control aspects of the longitudinal vehicle control problem is briefly reviewed. One approach to handling the logical aspects of the merging problem in automated systems assumes that vehicles occupy positions on a guideway within hypothetical 'cells' that move at a constant velocity. This approach simplifies the logical aspect of the longitudinal control problem. The problem of controlling vehicles to attain and maintain an assigned cell on a guideway is modeled in the paper as a linear state regulator optimal control problem. The resulting vehicle control scheme requires less information feedback than alternative schemes, and exhibits good vehicle response characteristics. Alternative control strategies that lead to optimal control problems other than the linear state regulator are discussed, and the relative advantages of the scheme presented in the paper are pointed out. [ABSTRACT FROM AUTHOR]

In two papers by C. J. ANCKER, JR., A. F. GAFARIAN, AND R. K. GRAY, the structure of the headways at the passage of an oversaturated signalized intersection were studied. The statistical analysis performed by these authors seems to confirm the hypothesis that these headways are independent random variables. In this paper we consider the following simple model. Let the spacings and reaction times of the vehicles stopped at the intersection all be independent and let the trajectory relative to the start position and start time be the same for all stopped vehicles. It is shown that the head- ways at the intersection are independent if and only if this trajectory is linear in a certain region specified in the paper. [ABSTRACT FROM AUTHOR]

This paper describes the examination of an oversaturated signalized intersection with no turning permitted. During the green phase, data on the time between arrivals of successive vehicles at an intersection with no downstream bottleneck have been collected and analyzed. Measurements were made of only the vehicles in queue, i.e., vehicles that were stopped during the red phase and those that were stopped during the green phase because the starting wave had not traveled back far enough. Measurements were made only on weekdays from approximately 7:00 A.M. to 8:45 A.M. in order to restrict the sample, as far as possible, to commuters. It is shown that shifted Erlang density functions fit the data satisfactorily and that all vehicles from the third on may be considered as members of the same population with different means. The mean arrival times decrease from front to rear with all from the seventh on being the same. In addition, our statistical analysis leads us to accept the hypothesis that all interarrival times are independent. Experimental techniques and statistical methods are described. Two uses of these results are (1) to provide in- formation for Monte Carlo simulations of traffic phenomena in which oversaturated situations are being considered, and (2) to develop, as will be done in a subsequent paper, a renewal model that takes account of variability in the empyting process, and that may be used in formulating control policies for the oversaturated situation. [ABSTRACT FROM AUTHOR]

This paper presents a mathematical model for the behavior of right- turning (left-hand drive is the convention observed) vehicles at an uncontrolled intersection. The model is a development of the one proposed for this situation in a previous paper by the author. It relates to the intersection of a two-lane major road with a minor road at which vehicles on the major road have absolute priority. Completely random traffic is postulated on the major road, and congestion is caused by drivers of vehicles on the major road who wish to turn right and are unable to do so immediately because of oncoming traffic. It is not possible for following vehicles to filler to the left of a delayed vehicle. The delay distribution for vehicles in each lane of the major road is determined for the case of stochastically stationary behavior, and sonic numerical results for the mean and variance of this distribution are given. The gap acceptance mechanism used in this paper is similar to the one proposed by GAVER. Further references for this paper are discussed in the Introduction to the author's previous paper. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A particular case of 'blind approach' is considered: that in which two vehicles travel with different speeds along parallel mean paths in a two-dimensional region. It is shown that the problem of calculating the probability of safe passage can be put in the form of equivalent zero-crossing problems for stationary, nonzero mean random processes, within a relatively long record. A lower bound for the probability of absence of zero-crossings is given in the form of a finite sum and some arguments on convergence are discussed. [ABSTRACT FROM AUTHOR]

This article presents information regarding the International Conference on "High Speed Ground Transportation," which is to be held on the campus of Arizona State University from January 7-10, 1975. Papers are requested on both the state-of-the-art and current research in all facets of high speed ground transportation. Fields to be emphasized include: vehicle and guideway; structures propulsion; vehicle and guideway; dynamics; communications and controls; systems optimization; noise and air pollution; regional land planning, new cities; airport access; cargo movement; finance; safety; social and legal factors. The abstract deadline is October 15, 1973, with prospective authors to be notified by November 15, 1973. Manuscripts are requested by April 15, 1974. The papers presented at the conference will be published in the "High Speed Ground Transportation Journal." The abstract limit is 500 words.

Focuses on a study which modified estimates of annual road costs and the classification of heavy vehicles in Canada. Methods and findings; Components of revenue estimates; Conclusion.

The article focuses on a new legislation to intensify the control of Parliament over the railway system. It was alleged that such a policy would be at once unjust and impracticable. The policy has been carried out, although the justice of it is perhaps still open to question, and the practical working of the revised scale has already produced much friction between the traders and the Board of Trade on one side and the railway companies on the other. In detail the new legislation effects a series of compromises, and offers a series of propitiations. The small trader is propitiated by the refusal to the large trader of the benefit of a reduced rate for train-loads; while even the reduced rate for the truck-load is not so low as the large trader would like. The trader in through traffic is propitiated by the cumulative scale; while the owners of wagons and of sidings are considered in the provisions for dissecting rates, and the powers which make it possible for a trader to perform nearly all the functions of a railway company for himself if he chooses.

This article presents annotated bibliography of scientific research in road traffic and safety. It presents investigation of relations between theoretical models and data that is supposed to be described by the models. There are a few entries without annotation; these have not been inspected. Parentheses enclose symbols of secondary importance. The main stream of research reflected in the present bibliography falls into the first subject category, "Traffic," and it is with respect to this category that the bibliography purports to be complete. Selection of publications has been more difficult in the other four areas. The subject matter blends into several fields that the journal wish specifically to exclude; chief among these are: the construction and maintenance of highways and the furniture of highways; the various mechanical and electrical properties of vehicles; physiological and psychological aspects of the driving population; instruments and instrumental systems, including computers; economic and financial analysis, and medical and legal questions of all kinds.

A linear control algorithm is proposed for the computer operation of a signalized traffic intersection. A theoretical analysis of the algorithm under the assumption of constant vehicular arrival and departure rates shows that the control is stable under unsaturated conditions, and with proper choice of control constants usually gives a rapid convergence to a limit cycle that minimizes the average delay. [ABSTRACT FROM AUTHOR]

The manner in which vehicles follow each other on a highway (without passing) and the propagation disturbances down a line of vehicles has been investigated Experimental data is presented which indicates that the acceleration at time t of a car which is attempting to follow a leader is proportional to the difference in velocity of the two cars at a time (t-Δ) ,Δ being about 1 5 sec and the proportionality constant being about 037 sec-1 It is shown theoretically that the motion of a long line of vehicles becomes unstable when the product of the lag time and the proportionality constant exceeds one-half The experimental data implies that drying is done on the verge of instability A variety of other laws of following is analyzed theoretically [ABSTRACT FROM AUTHOR]