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.

Traffic surveillance method and vehicle flow control in a road network

Abstract: The invention relates to a method for traffic surveillance in a road network, wherein the actual or future traffic situation can be detected in one or several points of said network and wherein a distinction is made between three types of traffic situation: free traffic, synchronized traffic and traffic back-up. The invention also relates to a method for controlling the flow of vehicles, wherein surveillance of traffic situation in a segment of the network is carried out and the flow of vehicles in said segment is controlled depending on the traffic situation that has been detected. According to the invention, the traffic surveillance method is designed in such a way that transition from free to synchronized traffic and/or back-up can be detected or forecast on the basis of special criteria. According to the invention, the flow of vehicles in the segment of the road network under surveillance is controlled depending on the detected transition from free to synchronized traffic. The method according to the invention can be used, for example, in expressways.

Virtual Probe Approach for Time-Dependent Arterial Travel Time Estimation

Abstract: Travel time estimation on arterials is a challenging task for traffic engineers due to the interrupted nature of urban traffic flows. Many research efforts have been devoted on this topic, but their successes are limited and most of them can only be used for offline purposes due to the limited availability of traffic data from signalized intersections. With the advancement of intelligent transportation systems, high-resolution detector and signal status data are available but not fully explored. In this paper, we develop an innovative algorithm for time-dependent arterial travel time estimation by tracing a virtual probe vehicle. At each time step, the virtual probe has three possible maneuvers: acceleration, deceleration and no-speed-change. The maneuver decision is determined by its own status and its surrounding traffic conditions, which can be estimated based on the availability of traffic data at intersections. An interesting property of the proposed model is that travel time estimation errors can be self-corrected with the signal status data, because the differences between a virtual probe vehicle and a real probe can be reduced when both of them meet the red signal phase. A field study at an 11-intersections arterial corridor along France Avenue in Minneapolis, MN shows the proposed model can generate accurate time-dependent travel time under various traffic conditions.

An instantaneous kinematic wave theory of diverging traffic

Abstract: Diverging junctions are an important type of bottlenecks, which can reduce capacities and initiate and propagate traffic congestion in a road network. In this paper, we propose a kinematic wave theory for modeling dynamics of non-cooperative diverging traffic, in which traffic dynamics of vehicles to one direction are assumed to be independent of those to other directions instantaneously. During a short time interval, the kinematic wave model of diverging traffic is decoupled into a number of nonlinear resonant systems. From analytical solutions to the Riemann problem of a decoupled system, a new definition of partial traffic demand is introduced, so that diverging flows can be easily computed with the supply-demand method. Then a Cell Transmission Model is proposed to solve the kinematic wave model of diverging traffic by taking into account of the interactions among different traffic streams. Simulation results demonstrate that vehicles follow the First-In-First-Out principle in the long run, and the model converges when we decrease the cell and time-step sizes. In addition, it is shown that traffic streams to different directions segregate in a selfish manner, and the total throughput of a diverging junction is not maximized as in existing diverge models. In the future, more theoretical and empirical studies are needed for a better understanding of this and other diverge models.

Multiple ramp control for a freeway bottleneck

Abstract: MANY CURRENT APPROACHES TO FREEWAY CONTROL USE DETERMINISTIC MODELS OF TRAFFIC FLOW BASED ON THE CONTINUOUS FLOW-DENSITY CURVE. THIS PAPER PROPOSES A CONTROL STRATEGY BASED ON A TWO-STATE TRAFFIC FLOW PATTERN WITH THE PRIMARY CONTROL PARAMETER BEING THE PROBABILITY OF TRANSITION FROM UNCONGESTED FLOW TO CONGESTED FLOW. THE OBJECTIVE OF THE CONTROL IS TO MAXIMIZE THE REWARD ASSOCIATED WITH FREE FLOW. TRIAL SOLUTIONS INDICATE THAT FEASIBLE NUMERICAL VALUES FOR OPTIMUM CONTROL CAN BE EASILY OBTAINED, AND THESE WILL BE DEPENDENT ON THE LENGTH OF THE PEAK PERIOD. THE APPROACH SHOULD HAVE DIRECT APPLICABILITY TO EXISTING SURVEILLANCE AND CONTROL HARDWARE.

Impact Evaluation of a Driving Support System on Traffic Flow by Microscopic Traffic Simulation

Abstract: This article reports on a study that evaluated a driving support system by using a microscopic traffic simulation which was modified by adding the function of perception-response process. In this approach, a dangerous driving situation is assessed by detecting conflict through simulation. The authors defined a safety indicator named TIDSS (Time Integral of Difference of Space distance and Stopping distance) from the time integral of the relative distance between the leading and following vehicle when the leading vehicle brakes suddenly. They contend that this indicator is superior to existing indicators because it can evaluate any type of situation and can include the degree and duration of danger for each vehicle. The authors tested their proposed approach by using it to evaluate the adaptive cruise control system (ACC) and automated platoon system (APS) for heavy trucks on an urban expressway. Many cases with different installation rates of ACC and APS were simulated using the proposed approach, and the relation between installation rate, safety indicators, and traffic flow rate was analyzed. They conclude that the results support the use of ACC to mitigate dangerous situations on the expressway by decreasing the traffic flow rate. Alternately, introduction of APS might mitigate dangerous situations and also increase the traffic flow rate.