Hua Kuang

Traffic accidents on a single-lane road with multi-slowdown sections

In this paper, an extended cellular automaton model is proposed to simulate the complex characteristics of traffic flow and the probability of the occurrence of traffic accidents by considering the modified conditions for determining whether traffic accidents happen and the effect of multi-slowdown sections on a highway. The simulation results show that the multi-slowdown sections can lead to multiphase coexistences (i.e. free flow phase, congestion phase and saturation phase) in traffic system. The fundamental diagram shows that the number of slowdown section does not influence the mean velocity and the mean flow under the periodic boundary condition, but the existence of slowdown sections can effectively reduce the occurrence of traffic accident. In particular, it is found that the probability of car accidents to occur is the largest at the joint of the normal-speed section and slowdown section, and the underlying mechanism is analyzed. In addition, to design the appropriate limited speed and reduce the differences between the normal speed and limited speed will alleviate traffic congestion and reduce the occurrence of traffic accidents obviously.

Asymmetric effect on single-file dense pedestrian flow

In this paper, an extended optimal velocity model is proposed to simulate single-file dense pedestrian flow by considering asymmetric interaction (i.e. attractive force and repulsive force), which depends on the different distances between pedestrians. The stability condition of this model is obtained by using the linear stability theory. The phase diagram comparison and analysis show that asymmetric effect plays an important role in strengthening the stabilization of system. The modified Korteweg–de Vries (mKdV) equation near the critical point is derived by applying the reductive perturbation method. The pedestrian jam could be described by the kink–antikink soliton solution for the mKdV equation. From the simulation of space-time evolution of the pedestrians distance, it can be found that the asymmetric interaction is more efficient compared to the symmetric interaction in suppressing the pedestrian jam. Furthermore, the simulation results are consistent with the theoretical analysis as well as reproduce experimental phenomena better.

Heterogeneous Effect and Pattern Formation on Pedestrian Queue Dynamics

Based on the optimal velocity model, an extended optimal velocity model is proposed to simulate the movement characteristics of multi-types pedestrian queue by considering the differences among pedestrians (e.g., the differences in age and sex, etc.) and the asymmetric interaction. For the random distribution of pedestrian queue, the evolution rules of pedestrian movement and the formation mechanism of space-time pattern under two different boundary conditions are investigated. The numerical simulations show that the model can better describe the space-time distribution of pedestrian movement from microcosmic viewpoint and reproduce such important phenomena as the formation, dispersion of jams and multi-clusters movements.

Effects of the Visibility on Traffic Flow

Based on the NaSch model, an extended cellular automaton model is proposed to simulate traffic flow by considering the effects of visibility. Under the open boundary condition, the influences of the injection probability, disappearance probability and visibility are discussed. The simulation results show that the injection probability and disappearance probability within a certain range have an important effect on the flux, density and velocity. And traffic jams often occur in poor visibility areas, which can become a road bottleneck. Furthermore, in order to effectively decrease the occurrence of traffic jams, the injection probability and disappearance probability should be set up reasonably.

Effect of Multi-Slowdown Sections on Traffic Flow

Based on the NS model, an extended cellular automaton model is proposed to simulate complex characteristics and energy consumption of traffic flow with some slowdown sections on a highway by considering the number, speed limit and distribution of slowdown sections. The simulation results show that the present model can exhibit a multi-phase coexistence phenomenon, i.e., the freely moving phase, the maximum flow phase and the jamming phase coexist in traffic system. The fundamental diagram shows that the number of slowdown section has no influence on the mean velocity and flow. However, energy consumption increases with increase of the number of slowdown section at low density. In addition, it can be found that the speed limit and distribution of different slowdown sections have an important effect on traffic flow and energy consumption, and the underlying mechanism is also analyzed.

Asymmetric Effect on Jamming Transition in Biham-Middleton-Levine Traffic Model

Asymmetric effect on the dynamical jamming transition in Biham-Middleton-Levine (BML) model with random sequential update rule is studied. The numerical simulations show that under periodic boundary condition, the system exhibits a sharp transition from freely moving phase to completely jamming phase, and the critical density is smaller than that of original BML model with synchronous update rule. For the asymmetry of system size, it can be found that the critical density is independent of the system size only when the width W and the length L are larger than some critical values respectively. Furthermore, the phase diagram shows that the asymmetric effect of the number of vehicles in two different directions plays a key role in reducing the occurrence of jam, and the underlying mechanism is analyzed.

Energy Consumption in Traffic Flow with a Slowdown Section

Based on the Nagel-Schreckenberg model, an extended cellular automaton model is proposed to simulate the characteristics of the energy consumption in traffic flow with a slowdown section by considering the stochastic noise, the length and speed limit of the slowdown section. The simulation results show that the energy consumption is determined by the length Ls of the slowdown section as well as the speed limit Vs of the slowdown section. The smaller Vs and the larger Ls can effectively alleviate energy consumption. Through vehicle accidents and energy consumption analysis, an important conclusion is drawn that Vs =1 may be an optimum design to drive safely and reduce energy consumption from traffic control. Furthermore, the stochastic braking probability P has also an important effect on energy consumption.

Analytical Solution of Congested Traffic Pattern Formation for a Viscous High-Order Model

In this paper, a new viscous vehicular flow model proposed by Song et al is discussed from the perspective of the capability to reproduce nonlinear traffic behavors observed in real traffic. The linear stability condition for stationary and equilibrium flow is derived. Near the neutral stability curve, the Korteweg–de Vries (KdV) equation describing congested traffic pattern is derived with use of the reduction perturbation method. And the corresponding analytical soliton solution is obtained.