Showing papers on "Traffic count published in 1989"

Trip matrix estimation from link traffic counts: The congested network case

Abstract: This paper examines different formulations for estimating trip matrices on congested networks from link traffic count data. It is shown that several existing approaches can be expected to produce the same results when observed counts constitute a user optimal link flow pattern. This has important practical implications because of the computational difficulties associated with some of the formulations.

Estimation of origin-destination matrices from traffic counts using multiobjective programming formulations

Abstract: Origin-destination (O-D) trip matrices can be estimated by methods that use traffic volume counts. Assuming that we know the proportionate usage of each link by the interzonal traffic, a system of linear equations combining the O-D flow and the observed volumes can be formulated. This system is, in general, underspecified. To obtain a unique solution, additional information, often a target trip matrix, has to be used. The estimation problem can be interpreted as a problem that has two types of objectives, one of which is to satisfy the traffic counts constraints and the other to search for a solution as “close” as possible to the target matrix. Errors are normally present in the input data, and it is therefore reasonable to allow for solutions where the observed traffic volumes are not reproduced exactly. Depending on his/her degree of uncertainty or belief in the available information, the planner can choose to give more or less weight to the different objectives. To satisfy all the constraints to equality is only one extreme case in a continuum of possibilities. In this paper, we present multiobjective programming formulations for estimating O-D matrices. The main emphasis is to point out that multiobjective theory can be used in the interpretation of the problem. In a two-objective model, an aggregated entropy measure is defined for each type of information (targets and observations), and is used as the objective. In addition, a totally disaggregated multiobjective model is presented in which one objective for each target matrix element and each traffic count observation is defined. These models are then combined to make a general model. Different approaches for estimation of the magnitude of uncertainty and for specification of the weights of the objectives are discussed.

Estimation of turning flows at an intersection from traffic counts

Abstract: This report describes the principle of information minimization as a method for estimating turning flows at an intersection from the entry/exit flows at each approach. Two algorithms are described. The first algorithm is for the case when all approach entry/exit flows are available. The second algorithm is suitable for those situations when information on entry/exit flows are incomplete. This second algorithm is particularly useful for generating a complete set of turning flows from traffic counts retrievable from the control system SCATS. The algorithms are implemented in FORTRAN77 and are available freely as pilot versions in 1989 to those interested in experimenting with their own data. Examples are described in this report to illustrate how the programs can be employed for turning flow estimation at a single intersection, and at a paired or compound intersection. The results indicate that a convergent solution obtained from the information minimization algorithms may not be a correct solution in those cases when a priori or prior information is inadequate.

Traffic modelling in kuwait.: 1., development of a saturn network database

Abstract: The paper describes the development of a set of speed/flow and junction flow/delay curves specific to conditions in Kuwait and to the requirements of the SATURN suite. These are based on journey time and traffic count surveys conducted throughout the metropolitan area. The local modelling framework relies on SATURN simulation of appropriate junction operation, layout and capacities. The paper concentrates finally on comparing capacities observed at junctions (traffic signals, roundabouts and priority junctions) in Kuwait with predicted capacities using U.K. formulae

A history of traffic engineering in australia

Abstract: This report outlines the history of traffic engineering in Australia. Although some basic traffic engineering principles began to be enunciated in the late 1930s, it was not until the late 1940s that traffic engineering began to develop as a separate branch of highway engineering. This development was rapid, and by the end of the 1950s traffic engineering was well established and practised throughout Australia. Since 1960 there have been many significant developments in the theory and practice of traffic engineering, and traffic engineering applications have substantially increased throughout the nation and this situation is still continuing. The developments in traffic engineering over the last 20-25 years generally are well documented elsewhere. Accordingly, the more recent events and happenings are not covered in any detail, but rather emphasis has been placed on the earlier developments. The ISBN of the microfiche version is 0-86910-364-4. (Author/TRRL)

Road traffic monitoring using the trip 2 system. second international conference on road traffic monitoring

Abstract: This paper contains a brief review of present image processing systems used for traffic monitoring, including a discussion of the disadvantages of such systems. The trip 2 system is described in more detail. This differs from many earlier systems as it is based upon an inexpensive IBM at microcomputer and can process complex pattern information by simulating the operation of a neural network. The vehicle detection algorithm relies upon the ability of the trip 2 system to learn from example and discriminate between complex patterns within video images of traffic scenes. During site trials of the system it was possible to detect 99% of the vehicles and individual vehicle speeds to an accuracy of between plus or minus 8% and 17% respectively. The algorithms were capable of: (a) removing unwanted shadows from images; and (b) operating over periods during which light levels varied significantly. Research is currently being undertaken to investigate the application of such neural network pattern recognition techniques for traffic monitoring, (traffic counting, traffic flow monitoring and vehicle classification). (TRRL)

Quantification of the traffic parameters for road design in belgium . conference papers on the working days on traffic engineering 1989

Abstract: Traffic parameters for road design in Belgium were until recently deduced from a very specialised study in the sixties. Since then traffic counting has been primarily conducted by the ministry of public works to determine the growth and composition of traffic. In view of the constant evolution of axle load distribution, the geometric composition of freight traffic and the important part of international traffic on Belgian roads, a new study was started in 1988. This article describes the practical realisation of vehicle counting with automatic counting devices and axle load measurements by means of a capacitive weighpad. The first measurements are presented and the difference with earlier findings highlighted. Part of this contribution deals particularly with the precision of the dynamic axleload measurements. (TRRL)

A spectrum of applications of Mulatm in local area traffic management

Abstract: The MULATM traffic planning software is now firmly established as a practical tool for local area traffic management. There are now more than 70 users of the package around the world, including Canada, Germany, Indonesia, New Zealand, Singapore and the USA. In January 1989 there were 55 users in Australia, including 28 local government authorities. Many applications of MULATM are now available, and a selection of these are described in this paper. The chosen applications form a spectrum that defines the types of problems to which MULATM can be usefully applied. It also indicates the variety of levels at which users can apply the package. The spectrum of applications reported in the paper ranges from the use of the package as an inventory of the traffic network, through incremental analysis of the effects of local street traffic control devices, simulation of network-wide travel conditions and traffic impact analysis to the estimation of environmental impacts. A summary of known applications of MULATM in Australia is provided. The use of MULATM in a wide range of local government applications since 1985 has served to establish the package as an important and useful tool for small area traffic planning and analysis. Each new application contributes something new to the understanding of MULATM and its capabilities and limitations, and continues its evolutionary development. The use of PC-based models as 'desktop planning' tools is assisting the rapid development of the. state-of-the-art in local area traffic management, by accelerating the introduction of new technologies and procedures into engineering practice. In the end, however, the value of such developments should only be judged in terms of their value and use in professional engineering practice.