Tieqiao Tang

AN EXTENDED OV MODEL WITH CONSIDERATION OF DRIVER'S MEMORY

In this paper, the optimal velocity (OV) model is extended to take account of the effect that the drivers memory has on the car-following behavior. The stability condition of the proposed model is obtained by using linear stability theory. The modified Korteweg-de Vries (mKdV) equation is obtained and solved. Traffic flows in the headway-sensitivity space are classified into three types as stable, metastable and unstable. Both analytical and simulation results show that introduction of drivers memory in the acceleration can improve the stability of traffic flow. It is also found that the stable region will be enlarged with the increase of the past information considered. Finally, numerical tests show that properly considering drivers memory can improve the stability of traffic flow.

THE EFFECTS OF BUS STOP ON TRAFFIC FLOW

In this paper, we use the traffic flow model proposed by Tang et al. [Physica A 387, 6845 (2008)] to study the effects of bus stop on traffic flow. Our numerical tests show that bus stop will have great effects on the stability of traffic flow and that the effects are related to the initial density and the number of bus stops. The numerical results are accordant with the real traffic, which shows that the model proposed by Tang et al. can describe some complex traffic phenomena resulted by bus stop.

A DYNAMIC MODEL FOR THE HETEROGENEOUS TRAFFIC FLOW CONSISTING OF CAR, BICYCLE AND PEDESTRIAN

Based on the properties of the heterogeneous traffic flow consisting of car, bicycle and pedestrian, we in this paper present three individual-following models with the consideration of the friction effects, where the individual can here be referred to as car, bicycle or pedestrian in a unified manner. Using the relationship between the micro and macro variables, we obtain a dynamic model for heterogeneous traffic flow with the consideration of the friction effects. The analytical and numerical results show that the bicycle friction effect will reduce the car flow and speed and that the pedestrian friction effect will reduce the bicycle flow and speed, but the reductions are related to the bicycle and pedestrian density.

A MACRO MODEL FOR BICYCLE FLOW AND PEDESTRIAN FLOW WITH THE CONSIDERATION OF THE HONK EFFECTS

Based on the interactions among car, bicycle and pedestrian, we in this paper present a bicycle-following model and a pedestrian-following model with the consideration of the honk effects. Using the relationship between the micro and macro variables, we obtain a macro model for bicycle flow and pedestrian flow. The numerical results show that the honk effects can enhance the bicycle and pedestrian speeds and flows.

Vehicle's exhaust emissions under car-following model

In this paper, we explore each vehicles exhaust emissions under the full velocity difference (FVD) model and the car-following model with consideration of the traffic interruption probability during three typical traffic situations. Numerical results show that the vehicles exhaust emissions of the second model are less than those of the first model under the three typical traffic situations, which shows that the second model can reduce each vehicles exhaust emissions.

A SIGNAL LIGHT MODEL AND ITS STABILITY ANALYSIS

Based on the effects that signal light has on car-following behavior, this paper developed a new signal light model. Numerical tests show that our model can reproduce the cluster, the dissipation and the propagation of the stopping waves and starting waves resulted by signal light. Finally, linear stability analysis and simulation show that our model is always stable.

An improved cooperative adaptive cruise control (CACC) algorithm considering invalid communication

For the Cooperative Adaptive Cruise Control (CACC) Algorithm, existing research studies mainly focus on how inter-vehicle communication can be used to develop CACC controller, the influence of the communication delays and lags of the actuators to the string stability. However, whether the string stability can be guaranteed when inter-vehicle communication is invalid partially has hardly been considered. This paper presents an improved CACC algorithm based on the sliding mode control theory and analyses the range of CACC controller parameters to maintain string stability. A dynamic model of vehicle spacing deviation in a platoon is then established, and the string stability conditions under improved CACC are analyzed. Unlike the traditional CACC algorithms, the proposed algorithm can ensure the functionality of the CACC system even if inter-vehicle communication is partially invalid. Finally, this paper establishes a platoon of five vehicles to simulate the improved CACC algorithm in MATLAB/Simulink, and the simulation results demonstrate that the improved CACC algorithm can maintain the string stability of a CACC platoon through adjusting the controller parameters and enlarging the spacing to prevent accidents. With guaranteed string stability, the proposed CACC algorithm can prevent oscillation of vehicle spacing and reduce chain collision accidents under real-world circumstances. This research proposes an improved CACC algorithm, which can guarantee the string stability when inter-vehicle communication is invalid.

The Effects Of Taxi On Traffic Flow

Taxi will come to one complete halt during the boarding/alighting period and might produce stop-and-go without passengers, so it often produces traffic interruption on the single-lane system. Tang et al. pointed out that the traffic flow model [Chin. Phys. 18, 975 (2009)] can be used to directly describe various micro phenomena resulted by traffic interruption on the single-lane system, if we properly define the traffic interruption probability, so in this paper we adopt this model to study the micro phenomena resulted by taxi on the single-lane system. The numerical results show that this model can describe the effects that taxi has on the trails of each vehicles motion and the evolutions of the flow and the density on the single-lane system, but that these effects are relevant to the initial conditions of the whole system.

Effects of the Spatial Distance between Two Adjacent Bus Stops on Traffic Flow

Bus-stop is one important compositions of urban traffic system and often produces some traffic interruptions since the buses should stop at the bus stop. In urban traffic system, there are often multi bus stops on a road, so the distance between bus stops will have great effects on traffic flow and produce some complex traffic phenomena. In this paper, we use the traffic flow model to further study the properties of the traffic flow on a ring road with two bus stops. The numerical tests show that our model can describe the effects of the distance between two adjacent bus stops on the stability of traffic flow and reproduce some complex traffic phenomena under the action of difference distances, which just show that our model is reasonable.