Traffic wave

About: Traffic wave is a research topic. Over the lifetime, 2106 publications have been published within this topic receiving 62117 citations. The topic is also known as: phantom traffic jam & ghost jams.

The oversaturated intersection

Abstract: In this paper, the authors propose a means to reduce traffic congestion at signalized intersections through signal timing that is based on traffic flow models.

MASTER: macroscopic traffic simulation based on a gas-kinetic, non-local traffic model

Abstract: We present a gas-kinetic (Boltzmann-like) traffic equation that is not only suited for low vehicle densities, but also for the high-density regime, as it takes into account the forwardly directed interactions, effects of vehicular space requirements like increased interaction rates, and effects of velocity correlations that reflect the bunching of cars, at least partially. From this gas-kinetic equation, we systematically derive the related macroscopic traffic equations. The corresponding partial differential equations for the vehicle density and average velocity are directly related to the quantities characterizing individual driver–vehicle behavior, and, as we show by calibration of the model, their optimal values have the expected order of magnitude. Therefore, the model allows to investigate the influences of varying street and weather conditions or freeway control measures. We point out that, because of the forwardly directed interactions, the macroscopic equations contain non-local instead of diffusion or viscosity terms. This resolves some of the inconsistencies found in previous models and allows for a fast and robust numerical integration, so that several thousand freeway kilometers can be simulated in real-time. It turns out that the model is in good agreement with the experimentally observed properties of freeway traffic flow. In particular, it reproduces the characteristic outflow and dissolution velocity of traffic jams, as well as the phase transition to “synchronized” congested traffic. We also reproduce the five different kinds of congested states that have been found close to on-ramps (or bottlenecks) and present a “phase diagram” of the different traffic states in dependence of the main flow and the ramp flow, showing that congested states are often induced by perturbations in the traffic flow. Finally, we introduce generalized macroscopic equations for multi-lane and multi-userclass traffic. With these, we investigate the differences between multi-lane simulations and simulations of the effective one-lane model.

Dynamic Model of Peak Period Traffic Congestion with Elastic Arrival Rates

Abstract: The paper develops a dynamic model of peak period traffic congestion that considers a limited number of bottlenecks. The model predicts the temporal distribution of traffic volumes with an elastic demand model. In response to changes in the traffic conditions travelers can switch to a different mode, divert to an alternate route, or shift the trip forward or backward in time to avoid a long delay. A simple example would be the case of two parallel routes with travelers jointly selecting route and departure time. The choice of route and mode are dependent on travel times and travel costs. The choice of departure time is based on the trade-off between travel time and schedule delay which is the difference between the actual and the desired arrival times. The delays at the bottlenecks are modeled with a deterministic queueing model that determines 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 the distribution of traffic is derived...

Some possibilities for using traffic control to influence trip distribution and route choice

Abstract: If the generalized cost to a vehicle of travelling along each link in a road network is a suitable known increasing function of the traffic flow on that link, and the number of journeys made per unit time between each point of entry to the network and each point of exit from it is a suitable known decreasing function of the generalized cost to a vehicle of travelling between the two points concerned, or is in accordance with a suitable gravity model, then the techniques of trip distribution and traffic assignment, together with suitable assumptions about drivers' choice of route, enable estimates to be made of the number of journeys between each entry point and each exit point, and the flow of traffic on each link. When all or part of the network is subject to traffic control, the relationships between travel cost and traffic flow on some or all of the links in the network depend on the control parameters, and these can therefore be used to influence the number of journeys made through the network and the routes taken. In this paper, a theoretical framework is developed for such use of traffic control when the method of control is linked traffic signals. The estimated numbers of journeys and traffic flows given by trip distribution and traffic assignment are treated as functions of the traffic control parameters so that these parameters can be chosen so as to improve the traffic pattern with respect to a suitable criterion. An examination is made of the possibility of using trip distribution, traffic assignment and traffic signal calculation techniques to investigate what the results of choosing traffic signal settings in this way might be. A numerical example is given for a simple situation in which a beneficial result could be achieved. /Author/