Search

A problem that is of interest in transportation planning, as well as other fields, is the effect on some or all of the shortest routes through a network, of increasing the length of a link in the network, or removing a link completely. A method is described for handling this problem, by establishing a subset of links, one of which must be contained in any alternative shortest path. These are referred to as the competing links. It is shown that this method has applications going beyond the particular problem cited. It may be applied to measuring the effects of altering some of the links in a network subjected to congested flow. The results presented for the algorithm compare very favorably with alternative procedures. It is suggested that the algorithm could be used in the development of networks which are, in some sense, optimal. [ABSTRACT FROM AUTHOR]

The article presents information on postwar reconstruction. The representatives of the towns and villages of the county as well as of the city have formed the Planning Federation of the Onondaga County Municipalities to carry on detailed planning of specific areas in line with the general postwar plans. The housing shortage, created largely by the families of returning soldiers, exceeded substantially all expectations, partly because of the unprecedented influx of veteran students to Syracuse University, partly because of the industrial expansion. Due to the shortage of construction materials, high cost and the general uncertainty, permanent construction did not have much chance to get under way. Traffic and parking-facility plans have received much attention because of the increasing traffic congestion. The inauguration of one-way traffic on the several streets of the central district was among the traffic-engineering measures constituting a distinct breakthrough of the opposition and skepticism of many years' standing.

The problem of optimizing the control of two oversaturated traffic intersections is solved by using the semi-graphical methods employed in a previous paper for an isolated intersection. As in the case of a single intersection the optimum control involves values of the control variables that lie along edges of the control region, which in this case is defined by the permissible ranges of the green phase splits. An analytical formulation of the method using PONTRYAGIN's control theory is also given. [ABSTRACT FROM AUTHOR]

In periods of traffic congestion, residual queues at intersections or the blocking of lanes limit the efficiency of synchronized signalization. A computer control scheme is developed that concentrates upon providing real-time, traffic-responsive corrective action for a "critical intersection control (CIC)," defined as a point in the network at which primary driver routes cross or those where congestion has arisen for other reasons, such as in the aftermath of an accident or stall. The approach taken in this article assumes "synchronization" schemes form the background control with fast, real-time, traffic-responsive corrective action being applied to critical congestion situations. The downstream delay in included because it is futile to reduce vehicle delay at an intersection at the cost of accumulating more delay downstream than was saved at the controlled intersection. The inclusion of the downstream delay also maintains a degree of coordination with neighboring intersections. The CIC produced large reductions in total delay for the subnetwork being considered during congestion situations. This is particularly encouraging because the controller delay computations are based upon a number of simplifying assumptions on the traffic flow, whereas the simulation evaluations were conducted with full consideration given to such factors as turning movements, lane changing and headway and speed relations.

The article presents an alternative method for determining the state probabilities in the multiple-channel case with fixed holding times and random arrivals. The author of this article claims that this method is less mathematically sophisticated and possesses practical advantages from the point of view of simplicity and convenience. This method is used to calculate the equilibrium-state probabilities in congestion problems in railroads. The author of this article outlines how the equations for this method is solved, as well as its variables used.

IT is now becoming generally realised that the most important transport problem in Britain today is not surplus capacity on the railways but excess demand on the roads. There are some, such as Professor Kolbuszewski of Birmingham, who have suggested that the problem of urban road congestion is so intractable that big-city life may eventually have to be abandoned. But in the meanwhile many partial solutions and remedies for urban congestion have been put forward. Amongst these is the special contribution of economists, the suggestion that a tax should be imposed on vehicles using congested roads.[2] The purpose of this article is to examine the case for a congestion tax as it is put forward in the Report of the Ministry of Transport Panel which met under the chairmanship of Dr. R. Smeed.[3] The aim of a congestion tax is to obtain a more efficient use of road space. If a congestion tax was imposed on all vehicles using congested roads, it is argued, some drivers would use alternative, less-congested routes, some would travel at a different time, some transfer from private to public transport, and others would decide that their journey was not really necessary. The basis of the theoretical case for a congestion tax is that at present there are some road users who would value the benefit gained from their use of road space at less than the "social" marginal costs which they impose on other road users. When the traffic flow on a road increases beyond a certain point vehicle operating costs per mile (fuel consumption, brake, tyre and engine wear) will rise. More importantly, average speeds will be reduced and journey times lengthened. Since people value the scarce resource of time, a slower journey may be said to be a more costly journey, and the "costs" of lost time added to increased operating costs give total congestion costs. [ABSTRACT FROM AUTHOR]

At the University College London, professor R.J. Smeed put forward a theory giving the amount of traffic which can enter a city during peak periods. According to Smeed's theory, the amount of traffic that can enter a city center is proportional to its area rather than its circumference. At the Tewksbury Symposium on Urban Development held at Melbourne University recently, one speaker put forward a theory that the amount of traffic that can enter a city center is proportional to its area rather than its circumference. The data provided are of 35 cities of which 20 are in Great Britain. This data was collected by professor Smeed, and is contained in appendix 1 Figure 1 in the article shows the results, a linear regression line was fitted by least squares to the logarithmic values. The gradient was found to be very close to the 0.5 predicted by Smeed's theory.

Focuses on the condition of congestion, the social costs of motoring will in Germany. Development of formula for the elasticity of velocity; Relationship between cost and speed; Interaction of demand function.