Corresponding Angle Feedback in an innovative weighted transportation system

The optimal information feedback has a significant effect on many socioeconomic systems like stock market and traffic systems aiming to make full use of resources. In this Letter, we study dynamics of traffic flow with real-time information. The influence of a feedback strategy named Corresponding Angle Feedback Strategy (CAFS) is introduced, based on a two-route scenario in which dynamic information can be generated and displayed on the board to guide road users to make a choice. Our model incorporates the effects of adaptability into the cellular automaton models of traffic flow and simulation results adopting this optimal information feedback strategy have demonstrated high efficiency in controlling spatial distribution of traffic patterns compared with the other three information feedback strategies, i.e., vehicle number and flux.     

Effects of prediction feedback in multi-route intelligent traffic systems

We first study the influence of an efficient feedback strategy named the prediction feedback strategy (PFS) based on a multi-route scenario in which dynamic information can be generated and displayed on the board to guide road users to make a choice. In this scenario, our model incorporates the effects of adaptability into the cellular automaton models of traffic flow. Simulation results adopting this optimal information feedback strategy have demonstrated high efficiency in controlling spatial distribution of traffic patterns compared with the other three information feedback strategies, i.e., vehicle number and flux. At the end of this paper, we also discuss in what situation PFS will become invalid in multi-route systems.     

含重叠路段交通系统中信息反馈策略的比较研究

智能交通系统可以实时反馈路况信息、诱导出行,进而缓解交通拥堵.在时间反馈和平均速度反馈两种信息服务策略下,考虑重叠路段的影响,利用元胞自动机模型对人们的路径选择行为进行了模拟.结果表明,在含有重叠路段的网络中,相对时间反馈策略而言,平均速度反馈策略可以更有效地降低人们的出行时间,其优势在重叠部分长度占路径长度的比例很小和较大时十分明显,且随路径长度的增加而上升.在提高路网的利用效率方面,平均速度反馈策略的优势随路径长度的增加而逐渐下降,随重叠部分长度的增加而先降后升. 关键词： 交通流 元胞自动机 智能交通系统 信息反馈策略     

利用智能决策的双通道交通流

考虑依据信息反馈进行智能决策的双通道交通流问题, 获得一定信息时，好的决策可以使效率提高.多个体资讯的分析及经验的反馈、判断、再适应是一个多个体复杂适应系统的本质性质，交通流也明显带有以上特性.研究表明，如果机械地利用不好的反馈信息，系统将会存在很大的振荡；智能地利用反馈信息，可以提高系统利用效率.因此，应在尽可能地提供好的反馈信息的同时合理地利用它们. 关键词： 元胞自动机 信息反馈 机械决策 智能决策     

New Feedback Control Model in the Lattice Hydrodynamic Model Considering the Historic Optimal Velocity Difference Effect

A feedback control model of lattice hydrodynamic model is proposed by taking the information of the historic optimal velocity into account for the traffic system. The modern control theory is applied for the linear stability condition with feedback control signal. The result shows that the stability of traffic flow is closely related to the information of the historic optimal velocity. Furthermore, numerical simulations conform that the new feedback control did increase the stability of traffic flow efficiently, which is in accord with theoretical analysis.     

Routing strategies in traffic network and phase transition in network traffic flow

The dynamics of information traffic over scale-free networks has been investigated systematically. A series of routing strategies of data packets have been proposed, including the local routing strategy, the next-nearest-neighbour routing strategy, and the mixed routing strategy based on local static and dynamic information. The capacity of the network can be quantified by the phase transition from free flow state to congestion state. The optimal parameter values of each model leading to the highest efficiency of scale-free networked traffic systems have been found. Moreover, we have found hysteretic loop in networked traffic systems with finite packets delivering ability. Such hysteretic loop indicates the existence of the bi-stable state in the traffic dynamics over scale-free networks.      

A weighted mean velocity feedback strategy in intelligent two-route traffic systems

Information feedback strategies can influence the traffic efficiency of intelligent traffic systems greatly.Based on the more practical symmetrical two-route scenario with one entrance and one exit,an improved weighted mean velocity feedback strategy(WMVFS) is proposed,which is not sensitive to the precision of global position system(GPS) devices.The applicability of WMVFS to different weight factors,aggressive probabilities,densities of dynamic vehicles,and different two-route scenarios(symmetrical scenario and asymmetrical scenario with a speed limit bottleneck) is analyzed.Results show that WMVFS achieves the best performance compared with three other information feedback strategies when considering the traffic flux and stability.     

考虑最邻近前车综合信息的反馈控制跟驰模型

拥堵控制中, 通过车辆运行状态感知与控制的交互融合, 实现对车辆有效控制的过程, 具有信息物理融合系统的典型特征. 本文基于Konishi等的研究工作, 从交通信息系统与交通物理系统融合的角度, 进一步考虑优化速度差和安全间距对车流的影响, 在耦合映射跟驰模型中, 提出了一种考虑最邻近前车综合信息的交通拥堵反馈控制方案. 运用反馈控制理论, 给出了头车速度发生变化时交通流保持稳定的条件, 并与前人工作进行了比较. 理论分析与数值模拟结果一致表明, 耦合映射跟驰模型在本文提出的控制方案下能更有效地抑制交通拥堵. 关键词： 交通流 交通拥堵控制 耦合映射跟驰模型 信息物理融合系统     

基于智能交通系统的耦合映射跟驰模型和交通拥堵控制

基于智能交通诱导信息，提出一种改进的耦合映射跟驰模型，用于描述单车道的交通流动力学特性及其拥堵控制.利用反馈控制理论，给出了在头车速度发生变化时交通流保持稳定的条件.分析结果表明，考虑前方更多车辆的信息对交通流有致稳作用，亦即稳定性条件明显减弱.数值模拟证实了理论分析的正确性，通过与他人相关工作的比较得知，考虑智能交通诱导信息能够更有效地抑制交通拥堵. 关键词： 交通流 智能交通系统 耦合映射跟驰模型 交通拥堵控制     

Optimal traffic networks topology: A complex networks perspective

We investigate and analyse an optimal traffic network structure for resisting traffic congestion with different volumes of traffic. For this aim, we introduce a cost function and user-equilibrium assignment (UE) which ensures the flow balance on traffic systems. Our finding is that an optimal network is strongly dependent on the total system flow. And the random network is most desirable when the system flow is small. But for the larger volume of traffic, the network with power-law degree distribution is the optimal one. Further study indicates, for scale-free networks, that the degree distribution exponent has large effects on the congestion of traffic network. Therefore, the volume of traffic and characteristic of network determine the optimal network structure so as to minimize the side-effect produced by traffic congestion.     

A comprehensive study of advanced information feedbacks in real-time intelligent traffic systems

In the intelligent transportation system, an effective feedback strategy is of crucial importance to the improvement of traffic condition and transport capability. Based on the seven previously introduced feedback strategies, a new one is introduced, called vacancy length feedback strategy (VLFS). The simulation results in the symmetrical two-route scenario with two exits suggest that VLFS is the optimal one among all the feedback strategies. It outperforms others in terms of the value, stability, average flux and balance of the vehicle number, and also exceeds others for the convenience of its application in the real traffic condition. The later simulation results in the asymmetrical two-route scenario with one exit also prove that VLFS is the best.     

Bandwidth allocation strategy for traffic systems of scale-free network

In this Letter, the bandwidth resource allocation strategy is considered for traffic systems of complex networks. With a finite resource of bandwidth, an allocation strategy with preference parameter α is proposed considering the links importance. The performance of bandwidth allocation strategy is studied for the local routing protocol and the shortest path protocol. When important links are slightly favored in the bandwidth allocation, the system can achieve the optimal traffic performance for the two routing protocols. For the shortest path protocol, we also give a method to estimate the network traffic capacity theoretically.     

Weighted mean velocity feedback strategy in intelligent two-route traffic systems

Information feedback strategies can influence the traffic efficiency of intelligent traffic systems greatly. Based on the more practical symmetrical two-route scenario with one entrance and one exit, an improved Weighted Mean Velocity Feedback Strategy (WMVFS) is proposed, which is not sensitive to the precision of Global Position System (GPS) devices. The applicability of WMVFS to different weight factors, aggressive probabilities, densities of dynamic vehicles, and different two-route scenarios (symmetrical scenario and asymmetrical scenario with a speed limit bottleneck) is analyzed. Results show that WMVFS achieves the best performance compared with three other information feedback strategies when considering the traffic flux and stability.     

A control method applied to mixed traffic flow for the coupled-map car-following model

In light of previous work [Phys. Rev. E 60 4000 （1999）], a modified coupled-map car-following model is proposed by considering the headways of two successive vehicles in front of a considered vehicle described by the optimal velocity function. The non-jam conditions are given on the basis of control theory. Through simulation, we find that our model can exhibit a better effect as p = 0.65, which is a parameter in the optimal velocity function. The control scheme, which was proposed by Zhao and Gao, is introduced into the modified model and the feedback gain range is determined. In addition, a modified control method is applied to a mixed traffic system that consists of two types of vehicle. The range of gains is also obtained by theoretical analysis. Comparisons between our method and that of Zhao and Gao are carried out, and the corresponding numerical simulation results demonstrate that the temporal behavior of traffic flow obtained using our method is better than that proposed by Zhao and Gao in mixed traffic systems.     

反馈控制双车道跟驰模型研究

通过引入合理的换道规则，将单车道反馈控制模型扩展成双车道交通流模型.数值仿真表明，与经典的优化速度双车道模型相比，由于引入适当的反馈控制信息，车辆速度波动变小或消失，系统不会出现严重的堵塞现象.这说明该双车道反馈控制模型能有效地抑制或缓解交通流堵塞. 关键词： 跟驰模型 双车道模型 反馈控制 堵塞抑制     

基于复杂网络的交通拥堵与传播动力学分析

本文运用改进的中观交通流模型,研究了网络拓扑结构对交通拥堵的影响,进而分析复杂网络上的交通传播动力学特征和传播规律.结论有助于提出消除交通拥堵的有效控制策略以及交通规划的合理方案. 关键词： 复杂网络 交通流 交通拥堵 传播特性     

Effective usage of shortest paths promotes transportation efficiency on scale-free networks

With rapid economic and social development, the problem of traffic congestion is getting more and more serious. Accordingly, network traffic models have attracted extensive attention. In this paper, we introduce a shortest-remaining-path-first queuing strategy into a network traffic model on Barabási–Albert scale-free networks under efficient routing protocol, where one packet’s delivery priority is related to its current distance to the destination. Compared with the traditional first-in-first-out queuing strategy, although the network capacity has no evident changes, some other indexes reflecting transportation efficiency are significantly improved in the congestion state. Extensive simulation results and discussions are carried out to explain the phenomena. Our work may be helpful for the designing of optimal networked-traffic systems.     

Traffic flow velocity disturbance characteristics and control strategy at the bottleneck of expressway

In the three-phase traffic flow studies, the traffic flow characteristic at the bottleneck section is a hot spot in the academic field. The controversy about the characteristics of the synchronized flow at bottleneck is also the main contradiction between the three-phase traffic flow theory and the traditional traffic flow theory. Under the framework of three-phase traffic flow theory, this paper takes the on-ramp as an example to discuss the traffic flow characteristics at the bottleneck section.In particular, this paper mainly conducts the micro-analysis to the effect of lane change under the two lane conditions, as well as the effect of the on-ramp on the main line traffic flow. It is found that when the main road flow is low, the greater the on-ramp inflow rate, the higher the average speed of the whole road section. As the probability of vehicles entering from the on-ramp increases, the flow and the average speed of the main road are gradually stabilized, and then the on-ramp inflow vehicles no longer have a significant impact on the traffic flow. In addition, this paper focuses on the velocity disturbance generated at the on-ramp, and proposes the corresponding on-ramp control strategy based on it, and the simulation verified that the control strategy can reasonably control the traffic flow by the on-ramp, which can meet the control strategy requirements to some extent.