Showing papers on "Traffic wave published in 1985"

Macroparticle traffic simulation model to investigate peak-period commuter decision dynamics.

Abstract: A special-purpose, macroscopic highway corridor traffic simulation model is presented. The model views traffic as discrete vehicle bunches or macroparticles that are moved according to local speeds defined by local concentrations, resulting in high computational efficiency. The model allows the investigation of commuter decision dynamics and their interrelation with timedependent congestion patterns. Two applications of the model are described illustrating its use (a) in conjunction with behavioral rules by which commuters respond to experienced congestion and (b) as part of an interactive experiment involving decision making by real commuters.

A reformulation of the theory of optimal congestion taxes

Abstract: A recent paper in this Journal (Else, 1981) presented a reformulation of the theory of optimal congestion taxes. The basic element in the reformulation is a model for determining the marginal social cost of road traffic. The model is a fruitful departure from the standard static model which has appeared in dozens of publications over the past two decades. But the approach used by Else in Part IV of his paper does not extend very satisfactorily to dealing with other than "short" roads. Indeed, the effect of lengthening the road in his model would simply be to dilute the effect of a given increase in the number of vehicles on the traffic density and, in view of the nature of the flow/density/journey-time relationship, to understate its effect on journey time. Here we suggest that longer roads could be dealt with more satis factorily by dividing them into standard lengths, though in practice there may be operational difficulties in defining standard lengths. Marginal social costs are defined by Else as the costs arising from the entry at time t0 of a single additional unit of traffic (additional vehicle), which for con venience is referred to as z. In the general case which Else considers (his section IV), there is initially a constant equilibrium traffic flow of F0 vehicles per minute along the road, and associated with this is a constant traffic density of D0, so that all vehicles using the road face a constant journey time of T0 minutes and costs of C0. It is assumed that z, the additional unit of traffic, has no effect on traffic ahead of z, but alters the density, flow rate and travel time for all traffic following z. More specifically: (a) The outflow rate continues to be F0 till z reaches the exit, at time

Effects of Capacity Constraints on Peak Period Traffic Congestion

Abstract: A model of peak period traffic congestion analyzes the effects of capacity constraints. The model predicts the temporal distribution of traffic volumes when the demand is elastic. In response to changes in traffic conditions travellers can switch to a different mode, alternate route. The delays are assumed to occur at bottlenecks and a queueing model is employed to determine the waiting time as a function of the length of the queue at the time of arrival at the bottleneck. The day to day adjustment of traffic is derived from a dynamic Markovian model. Numerical simulations demonstrate that elastic demand congestion may persist even when a bottleneck capacity is expanded to meet the highest level of existing traffic flows.