A dynamic model for traffic network flow

Concerning the link properties in traffic networks, we introduce a dynamic equation of road flow into each link, and thereby propose a dynamic model for network flow. Using this model, we investigate the evolutions of inflow, outflow and flow on each link caused by a small perturbation of the network inflow under different route choice rules. Numerical results show that the dynamic model can reasonably capture the basic characteristics of network flow.     

An extended heterogeneous car-following model accounting for anticipation driving behavior and mixed maximum speeds

The optimal driving speeds of the different vehicles may be different for the same headway. In the optimal velocity function of the optimal velocity (OV) model, the maximum speed $v_{\max }$ is an important parameter determining the optimal driving speed. A vehicle with higher maximum speed is more willing to drive faster than that with lower maximum speed in similar situation. By incorporating the anticipation driving behavior of relative velocity and mixed maximum speeds of different percentages into optimal velocity function, an extended heterogeneous car-following model is presented in this paper. The analytical linear stable condition for this extended heterogeneous traffic model is obtained by using linear stability theory. Numerical simulations are carried out to explore the complex phenomenon resulted from the cooperation between anticipation driving behavior and heterogeneous maximum speeds in the optimal velocity function. The analytical and numerical results all demonstrate that strengthening driver's anticipation effect can improve the stability of heterogeneous traffic flow, and increasing the lowest value in the mixed maximum speeds will result in more instability, but increasing the value or proportion of the part already having higher maximum speed will cause different stabilities at high or low traffic densities.     

A least-effort principle based model for heterogeneous pedestrian flow considering overtaking behavior

In the context of global aging, how to design traffic facilities for a population with a different age composition is of high importance. For this purpose, we propose a model based on the least effort principle to simulate heterogeneous pedestrian flow. In the model, the pedestrian is represented by a three-disc shaped agent. We add a new parameter to realize pedestrians' preference to avoid changing their direction of movement too quickly. The model is validated with numerous experimental data on unidirectional pedestrian flow. In addition, we investigate the influence of corridor width and velocity distribution of crowds on unidirectional heterogeneous pedestrian flow. The simulation results reflect that widening corridors could increase the specific flow for the crowd composed of two kinds of pedestrians with significantly different free velocities. Moreover, compared with a unified crowd, the crowd composed of pedestrians with great mobility differences requires a wider corridor to attain the same traffic efficiency. This study could be beneficial in providing a better understanding of heterogeneous pedestrian flow, and quantified outcomes could be applied in traffic facility design.     

A new lattice hydrodynamic traffic flow model with a consideration of multi-anticipation effect

We present a new multi-anticipation lattice hydrodynamic model based on the traffic anticipation effect in the real world.Applying the linear stability theory,we obtain the linear stability condition of the model.Through nonlinear analysis,we derive the modified Korteweg-de Vries equation to describe the propagating behaviour of a traffic density wave near the critical point.The good agreement between the simulation results and the analytical results shows that the stability of traffic flow can be enhanced when the multi-anticipation effect is considered.     

一种改进的两车道交通流格子模型

通过引入新的流量转移函数，改进了两车道交通流格子模型，克服了现有模型隐含的车辆向后运动缺陷.推导了模型的线性稳定性条件.数值模拟结果显示，对于轻度车流扰动，改进的模型可以满意地描述车辆换道过程和趋势. 关键词： 两车道交通流 交通流格子模型 稳定性条件     

A macro traffic flow model with probability distribution function

In this paper, we introduce three probability distribution functions into the dynamic equation and propose a macro traffic flow model to investigate the impacts of the probability distribution functions on the evolutions of traffic flow under three typical states (i.e., uniform flow, shock, rarefaction wave, and small perturbation). The numerical results indicate that the probability distribution functions do not change the density and speed distributions of uniform flow, produce a two-layer shock but have no prominent effects on rarefaction wave, and have little effect on small perturbation.     

Effect of looking backward on traffic flow in an extended multiple car-following model

In this paper, a new car-following model is proposed by incorporating the backward looking effect under certain conditions and multiple information of preceding cars in traffic flow. And the neutral stability condition of this model can be obtained by using the linear stability theory. Numerical simulation shows that the proposed model is theoretically an improvement over previous ones.     

A viscous continuum traffic flow model with consideration of the coupling effect for two-lane freeways

In this paper, the viscous continuum traffic flow model for a single lane is extended to the traffic flow for two-lane freeways. The proposed model is a higher-order continuum model considering the coupling and lane changing effects of the vehicles on two adjacent lanes. It results from integrating the Taylor series expansion of the viscous continuum traffic flow model proposed by Ge (2006 Physica A 371 667) into the multi-lane model presented by Daganzo (1997 Transpn. Res. B 31 83). Our proposed model may be used to describe non-anisotropic behaviour because of lane changing in multi-lane traffic. A linear stability analysis is given and the neutral stability condition is obtained. Also, issues related to lane changing, shock waves and rarefaction waves, local clustering and phase transition are investigated through a simulation experiment. The simulation results show that the proposed model is capable of explaining some particular traffic phenomena commonly observable in real world traffic flow.     

交通流的一维元胞自动机敏感驾驶模型

在一维交通流元胞自动机NaSch模型的基础上，优先考虑驾驶员的不确定性敏感预期行为， 将随机延迟过程放在确定性减速之前，从而建立一种新的一维元胞自动机交通流模型：敏感驾驶模型 （简称SDNaSch模型），并根据所给出的车辆状态演化的并行更新规则作了数值模 拟，模拟得到的基本图表明，与NaSch模型相比，道路交通量有较大提高，接近于实测数据 ，说明新模型能更贴切地描述交通现象；某些密度区域流量出现两个分支，表明在临界点附 近存在亚稳态；而且会出现畅行相与阻塞相的相分离界面. 从车辆速度分布演化的时空斑图 ，可以看到宽幅运动阻塞相的出现以及畅行相→宽幅运动阻塞相和宽幅运动阻塞相→畅行相 的相变. 接着，计及实际交通情况，考虑行驶车辆中一部分是敏感驾驶，而其余车辆按NaSc h模型规则行驶，数值模拟结果进一步证明，敏感驾驶因素对车流的作用是很大的，随着敏 感驾驶车辆的增多，道路容量也随之提高. 关键词： 交通流 元胞自动机模型 亚稳态 相分离 交通相变     

交通流量序列混沌特性分析及DFPSOVF预测模型

以实际采集的交通流量序列作为研究对象, 分别应用互信息法和虚假邻点法确定其延迟时间和最佳嵌入维数, 完成交通流量序列的相空间重构. 通过计算交通流量序列的饱和关联维数和最大Lyapunov指数判定其混沌特性. 以最小均方(LMS)算法为基础, 构建了一种基于Davidon-Fletcher-Powell方法的二阶Volterra模型(DFPSOVF), 其应用了一种可随输入信号变化而实时变化的基于后验误差假设的可变收敛因子技术. DFPSOVF模型避免了在Volterra模型中采用LMS自适应算法调整系数时参数选择不当引起的问题. 将DFPSOVF模型应用于具有混沌特性的短时交通流量预测, 结果表明: 当模型记忆长度与交通流量序列的嵌入维数选择一致时, 模型的预测精度较高, 可以满足交通诱导和交通控制的需要, 为智能交通控制提供了新方法、新思路及工程应用参考. 关键词： 交通流量 混沌 DFPSOVF模型 预测     

A new car-following model with consideration of roadside memorial

In this Letter, a car-following model with consideration of roadside memorial is proposed. The numerical results show that the proposed model can qualitatively describe the impacts of roadside memorial on traffic flow and the traffic risk coefficient. It is also shown that roadside memorial can enhance the traffic safety.     

交通灯控制下城市主干道双车道多速元胞自动机交通流模型研究

提出一个城市主干道双车道多速元胞自动机交通流模型，此模型采用开放性 边界条件，在考虑诸多实际因素影响情况下，研究了主干道中车站的设置、交通灯绿信比对 车流量和车流速度的影响.计算机模拟所得到的基本图（流量 速度图）能较好地反映在交 通灯控制下城市主干道交通流真实状况. 关键词： 元胞自动机模型 交通流 主干道     

Multiple car-following model of traffic flow and numerical simulation

On the basis of the full velocity difference (FVD) model, an improved multiple car-following (MCF) model is proposed by taking into account multiple information inputs from preceding vehicles. The linear stability condition of the model is obtained by using the linear stability theory. Through nonlinear analysis, a modified Korteweg-de Vries equation is constructed and solved. The traffic jam can thus be described by the kink--antikink soliton solution for the mKdV equation. The improvement of this new model over the previous ones lies in the fact that it not only theoretically retains many strong points of the previous ones, but also performs more realistically than others in the dynamical evolution of congestion. Furthermore, numerical simulation of traffic dynamics shows that the proposed model can avoid the disadvantage of negative velocity that occurs at small sensitivity coefficients λ in the FVD model by adjusting the information on the multiple leading vehicles. No collision occurs and no unrealistic deceleration appears in the improved model.     

交通流双车跟驰模型与数值仿真

基于全速度差(FVD)模型,考虑双前车信息的影响,提出了交通流双车跟驰模型.通过线性稳定性分析,得到了改进模型的稳定性条件. 与FVD模型对比研究表明,改进模型的稳定区域有明显增加.数值模拟结果表明,改进模型通过调节次近邻前车信息,可以避免FVD模型中因为反应系数较小时出现负速度的缺陷.同时也表明次近邻前车对交通流存在不可忽视的影响. 关键词： 交通流 双车跟驰模型 模拟     

Stabilisation analysis of multiple car-following model in traffic flow

An improved multiple car-following model is proposed by considering the arbitrary number of preceding cars, which includes both the headway and the velocity difference of multiple preceding cars. The stability condition of the extended model is obtained by using the linear stability theory. The modified Korteweg--de Vries equation is derived to describe the traffic behaviour near the critical point by applying the nonlinear analysis. Traffic flow can be also divided into three regions: stable, metastable and unstable regions. Numerical simulation is accordance with the analytical result for the model. And numerical simulation shows that the stabilisation of traffic is increasing by considering the information of more leading cars and there is unavoidable effect on traffic flow from the multiple leading cars' information.     

Honking noise corrections for traffic noise prediction models in heterogeneous traffic conditions like India

In developing countries like India, the nature of the composition of traffic is heterogeneous. A heterogeneous traffic flow consists of vehicles that have different sizes, speeds, vehicle spacing and operating characteristics. As a result of the widely varying speeds, vehicular dimensions, lack of lane disciplines, honking becomes inevitable. In addition, it changes the urban soundscape of developing countries. In heterogeneous traffic conditions, horn events increase noise level (L_den) by 0.5–13 dB(A) as compared to homogenous traffic conditions. Therefore, the traffic prediction models that are used for homogenous traffic conditions are not applicable in heterogeneous traffic conditions. To increase the accuracy of noise prediction models, in depth understanding of heterogeneous traffic noise is required. Understanding the real traffic noise characteristics requires quantification of some of the basic traffic flow characteristics such as speed, flow, Level Of Service (LOS) and density. In a given roadway, the noise level changes with density and LOS on the road. In this paper, a new factor for horn correction is introduced with respect of Level Of Service (LOS). The horn correction values can be incorporated in traffic noise models such as CRTN, FHWA, and RLS 90, while evaluating heterogeneous traffic conditions.     

A macroscopic traffic model for heterogeneous flow

A new macroscopic heterogeneous traffic flow model is proposed in this paper. Driver anticipation is developed using analogies from Darcy's law and is based on the time and lateral distance headways. An equilibrium velocity distribution for heterogeneous traffic based on traffic alignment is employed. The performance of the Extended Speed Gradient (ESG), Zhang and proposed models is compared for the same traffic conditions using the Roe decomposition technique. The results obtained show the significance of the time and lateral distance headways on the evolution of traffic flow. Further, the proposed model provides a more realistic characterization of traffic flow than the ESG and Zhang models.     

弯道交通流跟驰建模与稳定性分析

为发现弯道道路条件下交通流的演化特性及稳定条件,在全速度差最优模型的基础上,研究了弯道情况下的交通流跟驰模型表达式,并以状态空间法和控制系统的稳定性判据对其进行了稳定性分析,得到弯道情况下交通流的稳定条件,最后进行了数值模拟,验证了模型稳定条件的正确性.研究结果表明在相同的初始交通流密度情况下,弯道道路随着道路弧度的增大,交通流稳定性逐渐降低.     

两车道交通流耦合格子模型与数值仿真

考虑两车道耦合效应的影响和换道效应,提出了改进的两车道交通流耦合格子模型.同时,改进了换道时的流量转移率,这样更符合实际交通情况.通过线性稳定性分析,得到了改进模型的稳定性条件.数值模拟结果也表明,模型通过考虑耦合作用信息,更好地再现了换道情况,同时也表明两车道间的耦合效应对两车道交通流存在不可忽视的影响.