The effects of transportation system improvements on urban performances with heterogeneous residents

Through developing a spatial equilibrium model for a linear monocentric city with a bi-modal traffic corridor (i.e., highway and public transit), this paper examines the effects of transportation improvements (including the decreases of the fixed travel cost, the travel time and monetary cost per unit distance) on urban spatial structure and the utilities of the two resident classes, namely car-available-residents (CARs) and car-unavailable-residents (CURs). As a result, it is demonstrated that the city size increases with the improvements of vehicle-highway system and the degree of CARs’ travel mode choice rationality, but the improvement of public transit may produce a shrinkage rather than an expansion in city size. From the aspect of utility, both CARs and CURs benefit from the improvement of vehicle-highway system; however, the improvement of public transit might have an adverse effect on the utility of CARs. These findings would provide valuable reference for the future transportation and urban planning.     

Stochastic Route Choice Equilibrium Assignment for Travelers with Heterogeneous Regret Aversions

Most route choice models assume that people are completely rational. Recently, regret theory has attracted researchers’ attentions because of its power to depict real travel behavior. This paper proposes a multiclass stochastic user equilibrium assignment model by using regret theory. All users are differentiated by their own regret aversion. The route travel disutility for users of each class is defined as a linear combination of the travel time and anticipated regret. The proposed model is formulated as a variational inequality problem and solved by using the self-regulated averaging method. The numerical results show that users’ regret aversion indeed influences their route choice behavior and that users with high regret aversion are more inclined to change route choice when the traffic congestion degree varies.     

Cost-sharing in directed networks: Experimental study of equilibrium choice and system dynamics

This study reports the results of an experiment on directed networks with positive externalities induced by cost-sharing. Subjects participated in a network game in which they had to choose between private and public transportations. If a player chose public transportation, then she shared the travel cost equally with other players making the same choice, whereas if she chose private transportation, then her travel cost was fixed. Travel costs on the private route were manipulated across the two experimental conditions. In one condition, these costs were homogeneous among players; in the other condition, they were heterogeneous among players and only privately known. We found that half (none) of the player groups in the homogeneous (heterogeneous) condition converged toward the efficient equilibrium. Examination of the system dynamics shows that convergence toward efficiency was facilitated by: (1) the existence of an intermediate equilibrium choice; and (2) strategic teaching by which a farsighted player chooses strategies with poor short-term payoff in order to shift group decisions to the efficient equilibrium and thereby increase her own long-term benefit.     

基于预知OD的城市路网交通流路径优化研究

针对城市路网交通流分布不均引起的交通拥堵问题,提出了在预约出行交通背景下基于预知OD的交通流路径优化方法。首先,分析了预约出行交通背景下预知OD的数据环境;其次,根据动态用户均衡准则,对预知的OD进行流量分配,给出预约出行车辆的路径;接着,使用预测控制的方法,结合路网上预约车辆的状态,以路网上路段的饱和度和未预约车辆的行程时间最小化为目标,从系统和用户两个角度对未预约车辆的路径进行实时的诱导,通过连续时域的滚动优化控制,优化交通流的路径;最后,对本方法的实现和应用做了思考和探索,对本研究做了总结。     

基于行程费用的城市物流配送通道选择模型

从时间质量的角度出发,指出行程时间最小化和行程时间可靠性最大化是城市物流配送通道选择的两个重要目标。定义行程费用等于行程时间费用和行程时间可靠性费用的加权平均值。在此基础上,建立了基于行程费用的物流配送通道选择模型。最后,对北京市实际路网进行了实例分析。     

Modes of Commuting in Mumbai: A Discrete Choice Analysis

Using a nested multinomial logit model (NMNL), this paper estimates the choice probabilities and demand elasticities of various modal alternatives for Mumbai using 1990 trip origination and destination data. The results indicate that with an increase in the cost of private transit system, market share is reduced. The result of this experiment is highly elastic private commuting mode demand. In addition, reduction in the market share of own vehicles is larger than that of hired vehicles. The increase in the cost of mass transit system reduces its share but is inelastic. Decrease in the market share of one mode is accompanied by increase in the market share of others. Income has a positive effect on the market share of private transit modes, particularly on the own vehicles' share. Other explanatory variables such as distance have a negative effect on mass transit system and duration has a negative elasticity for all modes of transportation.     

北京市写字楼市场空间一体化模型研究——基于UrbanSim的模型标定与情景模拟

城市空间仿真系统(UrbanSim)为构建城市土地利用和交通空间一体化模型提供了基础平台。以写字楼市场为研究对象,基于企业选址和写字楼开发选址的相关理论构建了写字楼市场供给(开发选址)与需求(企业选址)一体化模型,通过地理信息系统(GIS)建立了北京市写字楼开发/价格、企业选址及城市基础设施和公共服务的空间数据库,并在UrbanSim平台上利用这些空间微观数据对写字楼市场一体化模型进行了标定。利用已标定的一体化模型,论文进行了城市政策效果和城市发展的情景模拟,包括轨道交通建设对企业选址和开发选址的影响,以及北京市两个重要的商务办公区(商务中心区和金融街)功能区扩张的预期效果。     

探究电气化铁道供电系统新技术的发展

伴随着我国经济的快速增长以及科学技术的持续提升,电气化铁路供电系统在发展中也获得了新技术以及新突破。同样,科学技术的发展也为人们带来了很大的便利,同时也为运输业带来了较多的机遇以及巨大的挑战。人们在旅行当中对交通的选择呈现出多样化的趋势,他们非常重视交通的安全性以及舒适性。通常情况下,首选的铁路运输属于运输系统当中非常重要的运输方式。在铁路运输当中,供电系统占据非常重要的地位。论文主要简单地介绍电气铁道供电系统新技术的发展情况,希望可以给大家带去一些启发。     

基于SPFA的整车物流运输线路及运输方式的优化及求解

运输成本对物流企业的作用至关重要,而运用计算机辅助技术来解决整车运输线路优化的问题也一直是物流企业关注的重点。文中以安吉整车物流现有的运输网络为研究对象,以运输成本最低为目标,建立运输线路及运输方式的优化模型,并运用改进后的SPFA算法编程进行求解,从而解决运输线路及运输方式的选择问题。希望通过研究在降低物流运输成本方面做出一些有益的探索。     

Fuzzy modelling of static system optimum traffic assignment problem having multi origin-destination pair

Traffic congestion is an unpreventable problem to avoid in a transportation network and it has negative effects on traffic accident, time wasting, traffic delay and safety problem. Besides, in transportation networks, drivers do not want to deal with traffic jam while traversing between specified origin-destination pair. Therefore, traffic assignment (TA) is imperative to improve traffic management, transportation safety, time, and cost savings. System Optimum Traffic Assignment Problem (SOTAP) is a kind of TA model which aims to minimize the total system travel time on the network, and satisfies the flow conservation constraints. To model the SOTAP more realistically, the imprecise parameters can be taken as fuzzy. Therefore, in this paper, we focus on converting the conventional SOTAP to a fuzzy quadratic programming problem (QPP) which is named System Optimum Fuzzy Traffic Assignment Problem (SOFTAP). Here, link travel time is expressed with BPR function as generally used in the literature by converting to fuzzy except link-dependent parameters. Thus, the nonlinear objective function of SOFTAP is expressed in terms of fuzzy link flows and fuzzy link travel times. A solution approach from the literature is modified to the reconstructed SOFTAP.     

基于灰色关联的应急物流最优路径选择

面对突发事故,合理运输路径的选择旨在最大程度的提高救援效率。文中选定运输时间、运输距离、行驶困难度、货物运输的安全性和运输组织的有效性五个指标,利用熵值法来确定各评价指标的权重系数,并运用灰色关联理论建立了应急物流的最优路径选择方法。     

基于多种运输方式的第四方物流路径问题研究

建立了基于多种运输方式的第四方物流路径优化模型,通过虚拟运输网络,将第四方物流路径问题转化为一个带时间约束和能力约束的最短路径问题,并给出了基于Dijkstra的启发式算法。算例显示,该算法能方便有效地求解基于多种运输方式的第四方物流路径问题。     

物流实时配送系统优化模型的构建与求解分析研究

为了解决物流实时配送系统过程的具体实施问题,以满足人们不断增长的物流需求,本文主要研究物流实时配送系统问题中,最优的配送中心个数,配送中心的选址,配送运输车辆行程路线安排,探讨寻求解决问题的有效方法,从而构建适当的运筹学数学模型,并对模型的求解进行深入透彻的分析研究,以实现整个集成物流系统的最小成本,从而实现最优化目标。为物流配送企业解决此类问题提供了思路和方法,并在部分企业进行了实证运用。     

A new look at the two-mode problem

This paper considers the second-best policy problem that arises when auto travel is priced below its marginal cost and there is a substitute mass transit mode. We analyze the problem by combining a model of a rail line based on Kraus and Yoshida (J. Urban Econ. 51 (2002) 170) with the highway bottleneck model. The model involves a transit authority which optimizes, in addition to the fare, two dimensions of transit capacity. These are (1) the number of train units serving the route and (2) the capacity of an individual train unit. Under a very weak condition, second-best optimality involves expanding both dimensions of transit capacity. The larger percentage effect is on train capacity.     

Spatial competition under uniform delivered pricing

A Hotelling-type model of spatial competition is considered, in which two firms compete in uniform delivered prices. First, it is shown that there exists no uniform delivered price–location equilibrium when the product sold by the firms is perfectly homogeneous andwhen consumers buy from the firm quoting the lower delivered price. Second, when the product is heterogeneous and when preferences are identically, independently Weibull-distributed with standard deviation μ, we prove that there exists a single uniform delivered price–location equilibrium iff μ≧1/8 times the transportation rate times the size of the market. In equilibrium, firms are located at the center of the market and charge the same uniform delivered price, which equals their average transportation cost, plus a mark-up of 2μ. Finally, we discuss how our result extends to the case of n firms and proceed to a comparison of equilibria under uniform mill and delivered pricing.     

基于改进遗传算法的多式联运路径优化研究

文中以荣森物流公司为研究背景,针对多运输方式多路径问题,提出一种改进的遗传算法,可同时解决运输方式的选择和路径的规划问题。通过建立多式联运路径优化模型,采用多参数编码方式,从而解决该类问题,同时为多式联运的相关决策和组织提供参考依据。     

Mixed Duopoly with Subcontracting

Existing literature on mixed oligopoly focuses on competition among different types of firms but ignores their possible cooperation. We allow cooperation between a public firm and a private firm through subcontracting in a Hotelling mixed‐duopoly model. We find that when subcontracting is possible, the equilibrium without subcontracting is not socially optimal because subcontracting can lower total production costs. And if both firms engage in subcontracting, the existence of a public firm can guarantee the first best equilibrium, whether it is the low‐cost firm or not. But when a private firm is the low‐cost firm, it is more profitable for it to choose vertical foreclosure. And the consequent equilibrium is not socially desirable anymore. Copyright © 2014 John Wiley & Sons, Ltd.     

城市公交线路选择算法优化

为提高城市居民乘坐公交出行的意愿,解决出行路径选择问题。拟从居民乘坐公交车出行的换乘次数最少为前提,提出用广度优先迭代结合Dijkstra算法为居民出行提供最优的公交线路。首先用广度优先迭代找出连接起讫点之间所有的换乘次数最少的公交线路,再使用Dijkstra算法在换乘次数少的线路中找到行程时间最短的线路,使得乘客在整个乘坐公交出行过程中换乘次数最少、乘坐时间最少。采用python编程实现结果验证,与实际结果路线对比,所提供的线路接近于实际运营,证明了该算法的有效性并且运行速度较快。