A new lattice model of traffic flow with the consideration of individual difference of anticipation driving behavior

In this paper, we propose a new lattice model of traffic flow with the consideration of individual difference of anticipation driving behavior. The linear stability condition and the mKdV equation are derived from linear stability analysis and nonlinear analysis, respectively. Furthermore, numerical simulation shows that the anticipation driving behavior can increase the cell number of low density, which means that more cars can run freely and traffic congestion can be suppressed efficiently by taking the anticipation driving behavior into account in lattice model. Moreover, with the coefficient of the anticipation driving behavior increasing, the low density region turns wide corresponding to individual difference of anticipation driving behavior.     

Nonlinear analysis of lattice model with consideration of optimal current difference

Based on Li’s lattice model, a new lattice model considering the influence of optimal current difference information is presented. The linear stability criterion of this model is obtained by employing the linear stability theory. The results show that the new consideration contributes to the stabilization of traffic systems. The modified Korteweg-de Vries (mKdV) equation is derived by using the nonlinear analysis method. The occurrence of traffic jamming transitions could be thus described by the kink-antikink soliton solution for the mKdV equation. From the simulation results of space–time evolution of the vehicle density, it is shown that the traffic jam is suppressed efficiently with considering the information of optimal current difference, and the analytical results is in good agreement with the simulation ones.     

Kink–antikink density wave of an extended car-following model in a cooperative driving system

We propose an extended optimal velocity model applicable to cooperative driving control system by considering the headway of arbitrary number of cars that precede and the relative velocity. The stability condition of the extended model is obtained by using the linear stability theory. The modified Korteweg-de Vries (mKdV) equation is derived to describe the traffic behavior near the critical point by applying the nonlinear analysis. Thus the traffic jams can be described by the kink–antikink density wave which is the solution of the mKdV equation. The simulation results confirm the analytical results and show that the traffic jams are suppressed more efficiently with considering not only the headway of more vehicles ahead but also the relative velocity.     

Analysis of a modified two-lane lattice model by considering the density difference effect

In this paper, a modified lattice hydrodynamic model of traffic flow is proposed by considering the density difference between leading and following lattice for two-lane system. The effect of density difference on the stability of traffic flow is examined through linear stability analysis and shown that the density difference term can significantly enlarge the stability region on the phase diagram. To describe the phase transition of traffic flow, the Burgers equation and mKdV equation near the critical point are derived through nonlinear analysis. To verify the theoretical findings, numerical simulation is conducted which confirms that traffic jam can be suppressed efficiently by considering the density difference effect in the modified lattice model for two-lane traffic.     

An extended multi-anticipative delay model of traffic flow

An extended multi-anticipative delay model is proposed by introducing multiple velocity differences and incorporating the reaction-time delay of drivers. The stability condition of the new model is obtained by applying the linear stability theory, and the modified Korteweg–de Vries (mKdV) equation is derived by the use of the nonlinear analysis method. The analytical and numerical results show that both the reaction-time delay of drivers and the information of multiple velocity differences have an important influence on the stability of the model, and that the stabilization of traffic flow is enhanced by appending the velocity difference information of multiple vehicles ahead or by decreasing the delay time.     

Effect of the optimal velocity function on traffic phase transitions in lattice hydrodynamic models

The original lattice hydrodynamics models of traffic flow are extended to take into account the complex acceleration behavior of drivers. A new optimal velocity function which considers the stepwise acceleration effect and fits the observed data better is introduced. The stability conditions of these two models are obtained by using the linear stability theory. It is shown that the modified optimal velocity function has a remarkable influence on the neutral stability curve and the traffic phase transitions. In a certain vehicle’s density and driver’s sensitivity region, tri-stable states will occur. In addition, the properties of the multiple phases also depend on the asymmetry of the optimal velocity function and the stage number of multi-phase transitions is closely related to the turning points of the optimal velocity function. The validity and correctness of the analytical results is confirmed by numerical simulations.     

A new lattice model of two-lane traffic flow with the consideration of optimal current difference

In this paper, a new lattice model of traffic flow is proposed with the consideration of the optimal current difference for two-lane system. The linear stability condition is derived through linear stability analysis, which shows that the optimal current difference term can improve the stability of traffic flow. The mKdV equation is obtained through nonlinear analysis. Thus the space of traffic flow is divided into three regions: the stable region, the metastable region and the unstable region respectively. Moreover, numerical simulation confirms that the traffic jam can be suppressed efficiently by considering the optimal current difference effect in extended lattice model of two-lane traffic flow.     

Using fuzzy integral for evaluating subjectively perceived travel costs in a traffic assignment model

A good traffic assignment model can be a powerful tool to describe the characteristics of traffic behavior in a road network. The traffic assignment results often play an important role in transportation planning, e.g., an optimal and economical network design. Many traditional traffic assignment models rely heavily on the travel cost function established by Wardrop’s principles; however, the Wardrop’s travel cost function has been proven to be weak for explaining the uncertainty and interactivity of traffic among links. This study tries to construct a traffic assignment model that is different from Wardrop’s in many aspects. First, it considers the cross-effect among the links. Second, a fuzzy travel cost function is established based on the possibility concept instead of precise calculation of traffic volumes. Third, the techniques of fuzzy measure and fuzzy integral are applied to calculate the subjectively perceived travel costs during traffic assignment. Furthermore, in order to validate our model, a detailed network with 22 nodes and 36 links is used to illustrate it. Study results show that our model explains more interactivity and uncertainty of traffic among links when compared with the traditional model of Wardrop’s.     

Analytical studies on the instabilities of heterogeneous intelligent traffic flow

It has been widely reported in literature that a small perturbation in traffic flow such as a sudden deceleration of a vehicle could lead to the formation of traffic jams without a clear bottleneck. These traffic jams are usually related to instabilities in traffic flow. The applications of intelligent traffic systems are a potential solution to reduce the amplitude or to eliminate the formation of such traffic instabilities. A lot of research has been conducted to theoretically study the effect of intelligent vehicles, for example adaptive cruise control vehicles, using either computer simulation or analytical method. However, most current analytical research has only applied to single class traffic flow. To this end, the main topic of this paper is to perform a linear stability analysis to find the stability threshold of heterogeneous traffic flow using microscopic models, particularly the effect of intelligent vehicles on heterogeneous (or multi-class) traffic flow instabilities. The analytical results will show how intelligent vehicle percentages affect the stability of multi-class traffic flow.     

基于季节ARIMA模型的GSM话务量建模和预报

本文用季节模型对天津移动GSM网的话务量进行了建模分析和预报,研究表明用季节模型对移动话务量进行建模分析和预报是可行的,同时在文中我们还给出了带两个周期季ARIMA模型的一般表达式,并用这种带多个周期的模型对实际的网络业务进行了建模和预报。     

Hölder continuity of solutions to elastic traffic network models

This paper aims to study stability and sensitivity analysis for quasi-variational inequalities which model traffic network equilibrium problems with elastic travel demand. In particular, we provide a Hölder stability result under parametric perturbations.     

不同行为风格下路段行人与机动车行为博弈分析

针对路段过街行人与机动车的博弈决策行为,考虑不同交通行为风格下行人的过街特征和驾驶人的驾驶行为习惯等影响因素,开展路段行人交通行为风格调查,掌握不同交通行为风格下路段行人的过街特征,构建非合作动态人车博弈模型.通过分析不同策略下行人与驾驶人的收益,求解纳什均衡,得到不同策略下行人与驾驶人的最优策略.为解决路段行人与机动车冲突提供新的思路.     

Notes on conditional previsions

The personalist conception of probability is often explicated in terms of betting rates acceptable to an individual. A common approach, that of de Finetti for example, assumes that the individual is willing to take either side of the bet, so that the bet is “fair” from the individual’s point of view. This can sometimes be unrealistic, and leads to difficulties in the case of conditional probabilities or previsions. An alternative conception is presented in which it is only assumed that the collection of acceptable bets forms a convex cone, rather than a linear space. This leads to the more general conception of an upper conditional prevision. The main concerns of the paper are with the extension of upper conditional previsions. The main result is that any upper conditional prevision is the upper envelope of a family of additive conditional previsions.     

Binary integer modeling of the traffic flow optimization problem,in the case of an autonomous transportation system

Our research aimed to optimize the transportation processes through the binary integer modeling of cooperative vehicle control by linking the dynamic traffic assignment approach and controlling the autonomous transport system. Our paper’s main contribution is a model transforming the optimal vehicle control problem into binary integer formulation, optimizing transport processes at the system level, and representing safety and dynamics related constraints on the vehicle level. Two small numerical case studies have illustrated the applicability and effectiveness of the model.     

Stabilization of traffic flow in optimal velocity model via delayed-feedback control

Traffic jams may occur due to various reasons, such as traffic accidents, lane reductions and on-ramps. In order to suppress the traffic congestion in an optimal velocity traffic model without any driver’s delay taken into account, a delayed-feedback control of both displacement and velocity differences is proposed in this study. By using the delay-independent stability criteria and the H_∞-norm, the delayed-feedback control can be determined to stabilize the unstable traffic flow and suppress the traffic jam. The numerical case studies are given to demonstrate and verify the new control method. Furthermore, a comparison is made between the new control method and the method proposed by Konishi et al. [K. Konishi, M. Hirai, H. Kokame, Decentralized delayed-feedback control of an optimal velocity traffic model, Eur. Phys. J. B 15 (2000) 715–722]. The results show that the new control method makes the traffic flow more stable and improves the control performance.     

Four species CA model for facing pedestrian traffic at rush hour

A model for the facing pedestrian traffic on a passage with a partition line at rush hour is developed. The model is described by a bi-directional cellular automaton (CA) model with four species. The CA model is not stochastic but deterministic. If the passage is congested and the local density is superior to the threshold, walkers to the east and to the west try to move separately changing their lane as the traffic rule is imposed on pedestrians at a high density. Walkers move freely ignoring the partition line at a low density. The traffic-rule effect at rush hour is taken into account in addition to the excluded-volume effect and bi-directionality. The pedestrian behavior under the traffic rule is clarified.     

Instability of cooperative adaptive cruise control traffic flow: A macroscopic approach

This paper proposes a macroscopic model to describe the operations of cooperative adaptive cruise control (CACC) traffic flow, which is an extension of adaptive cruise control (ACC) traffic flow. In CACC traffic flow a vehicle can exchange information with many preceding vehicles through wireless communication. Due to such communication the CACC vehicle can follow its leader at a closer distance than the ACC vehicle. The stability diagrams are constructed from the developed model based on the linear and nonlinear stability method for a certain model parameter set. It is found analytically that CACC vehicles enhance the stabilization of traffic flow with respect to both small and large perturbations compared to ACC vehicles. Numerical simulation is carried out to support our analytical findings. Based on the nonlinear stability analysis, we will show analytically and numerically that the CACC system better improves the dynamic equilibrium capacity over the ACC system. We have argued that in parallel to microscopic models for CACC traffic flow, the newly developed macroscopic will provide a complete insight into the dynamics of intelligent traffic flow.     

Novel travel cost functions based on morning peak commuting equilibrium

This paper derives two novel travel cost functions by formulating a morning commuting equilibrium model that incorporates traffic congestion based on fundamental traffic flow diagram. The travel cost functions have components to represent traversal cost, waiting queuing costs and early arrival penalty. It is found that the equilibrium travel cost is a concave function of the total demand in the uncongested regime but an increasing linear function of the total demand in the congested regime.     

A continuous-time linear complementarity system for dynamic user equilibria in single bottleneck traffic flows

This paper formally introduces a linear complementarity system (LCS) formulation for a continuous-time, multi-user class, dynamic user equilibrium (DUE) model for the determination of trip timing decisions in a simplified single bottleneck model. Existence of a Lipschitz solution trajectory to the model is established by a constructive time-stepping method whose convergence is rigorously analyzed. The solvability of the time-discretized subproblems by Lemke’s algorithm is also proved. Combining linear complementarity with ordinary differential equations and being a new entry to the mathematical programming field, the LCS provides a computational tractable framework for the rigorous treatment of the DUE problem in continuous time; this paper makes a positive contribution in this promising research venue pertaining to the application of differential variational theory to dynamic traffic problems.     

Sensitivity analysis for the asymmetric network equilibrium problem

We consider the asymmetric continuous traffic equilibrium network model with fixed demands where the travel cost on each link of the transportation network may depend on the flow on this as well as other links of the network and we perform stability and sensitivity analysis. Assuming that the travel cost functions are monotone we first show that the traffic equlibrium pattern depends continuously upon the assigned travel demands and travel cost functions. We then focus on the delicate question of predicting the direction of the change in the traffic pattern and the incurred travel costs resulting from changes in the travel cost functions and travel demands and attempt to elucidate certain counter intuitive phenomena such as ‘Braess' paradox’. Our analysis depends crucially on the fact that the governing equilibrium conditions can be formulated as a variational inequality. This work was supported by the Program of University Research, U.S. Department of Transportation (Project number DTRS 5680-C-00007).