Bus Rapid Transit System in Istanbul: A Success Story or Flawed Planning Decision?

Abstract

There is a growing tendency in cities around the world to invest in Bus Rapid Transit (BRT) systems in an attempt to improve the capacity and quality of public transport services. The appeal of BRTs is based on their ability to combine the service level of rail transit systems with the flexibility of buses at relatively lower investment costs, and this was the motivation behind the opening of such a system in the Turkish city of Istanbul in 2007. This system has attracted mixed opinions as to its performance, as while passenger ridership figures are extremely high, proving the effectiveness of the system, there is an argument that the corridor should have been developed with rail technology, and that the BRT is failing to meet the demand. The paper presents a comprehensive analysis of this system, assessing its planning and performance through a comparative analysis of a number of BRTs in the world and Istanbul's metro and tram systems. The analysis confirms the success of the system in terms of passenger statistics, but also highlights a number of problems in certain planning decisions that should be addressed, thus taking the discussion beyond a simplified comparison of bus and rail technologies.     

Estimating Freight Transport Price Elasticity in Multi-mode Studies: A Review and Additional Results from a Multimodal Network Model

Abstract

The paper presents a detailed comparative review of price/cost elasticity estimates published in a number of studies on multi-mode freight transport demands. It attempts to determine which factors could explain the wide diversity of estimates: data aggregation, diversity of markets, and methodology. It also presents new estimates for rail, road, and waterway modes, derived from a multimodal freight network model of the Rhine area market. Direct and cross-elasticities are estimated for 11 groups of commodities and per distance category. The results are critically assessed by comparison with the reviewed studies. The paper concludes with a few recommendations about meaningful uses of existing estimates and the need for additional experiments with different methodologies applied on a common data basis.     

Statistical mechanics for analytic planning: an application to domestic air traffic in China

Abstract

Statistical mechanics has shown its usefulness when assessing the topology of many networks, including those of infrastructure. Its principles take into account the large-scale and network-wide effects of changes in its key parameters, which in turn may provide critical input when planning for infrastructure projects. One objective would be to modify the pattern of capacity expansions inside a system to make it less exposed to local shortfalls in demand. To illustrate our point, we shall use domestic air traffic in China; airports are spatially distributed and they also need to respond to the potential demand that they face locally. Airlines that control parts of the traffic system are identified as agents. A relationship between the agent's behavior and the system-wide level of variance in traffic flows can be established by regression analysis. It is shown how intervention on these agents would reduce negative traffic variance while enhancing a more balanced, less costly growth of the system itself.     

Flexible strategic planning of transport systems

Abstract

This paper presents a decision support methodology for long-range planning of transport systems that exhibits strategic flexibility and stochastic system parameters. Unlike one-off strategic decisions, flexible decisions should be dynamically reformulated with time. The proposed methodology is based on the construction of a tree structure of multiple interlinked tactical planning problems, each associated with a scenario in the tree, where problems under scenarios at intermediate dates incorporate in their formulation the solution of the corresponding problems associated with past (future) connected scenarios. The resulting tree structure of interconnected planning decisions becomes a strategic-tactical decision support system that allows managers to formulate suitable flexible strategic decisions that mitigate the consequences associated with downside scenarios while taking advantage of the upside opportunities. The methodology is applied to the planning of a fleet deployment through charter contracts where contract prices depend on both market behavior and the duration of the contract itself.     

考虑弹性需求的城市枢纽间多方式时刻表优化

针对城市客运枢纽间综合运输通道协同性欠缺、运输效率低等问题,提出考虑弹性需求的城市客运枢纽间多方式时刻表协同优化方法。基于多项Logit模型对枢纽间乘客出行方式选择行为进行建模,分析各方式时刻表变动对出行需求的影响;以乘客等待总时间,时刻调整总数量,时刻调整总时间最小为优化目标,考虑弹性需求、时间窗、容量限制等约束,构建枢纽间多方式时刻表协同优化模型,并基于非支配排序遗传算法,结合客流加载仿真过程设计模型求解算法;最 后,以“北京南站-北京首都国际机场”多方式通道为例检验模型的有效性。结果表明,时刻表优化方案的实施使各方式产生了较为明显的需求弹性变化效果,模型求解得到10种时刻表优化方案,其评价结果整体优于传统模型,最终筛选方案可缩短乘客等待时间10.36%。     

海南自贸港背景下海口市对外客运量预测研究

针对典型的海岛型城市海口市,综合考虑经济、政策、基础设施等多维度定性、定量影响因素,构建系统动力学模型,预测2020-2035年海口市对外客运需求量。预测结果显示,未来15年海口市对外客运需求呈稳步上升趋势,预计在2035年对外客运总量将突破8000万人次。GDP敏感性分析结果表明,当增速大于9%时,当前设施建设计划需要进一步加强,提前提高交通设施的供给能力;就业引进人口敏感性分析得出,人才引进规模控制在100万人左右可实现最大的经济效益,比60万人、140万人分别高出6.9%、5.1%;两种主要对外交通方式(机场和高铁)建设时序敏感性分析结果表明,机场开通相比高铁可拉动需求增长提高6.3%,这充分说明航空是海岛型城市对外出行的主要方式。     

时间阈值对公交不平等评价结果的影响

时间阈值对公交可达性计算结果的影响,是否进一步影响到公交不平等评价结果,尚不明 确。以浙江省海宁市为例,用一种改进的两步移动搜索法(E2SFCA)计算公交可达性,得到 10~90 min共9个时间阈值下研究区域的总体、市区和农村公交服务的基尼系数,比较了不同时间 阈值下的基尼系数差异;按市区和农村两个群组对总体基尼系数进行分解,分析在时间阈值下群 组内和群组间不平等对总体公交不平等的影响。结果发现：随时间阈值增大而基尼系数逐渐减 小,公交不平等评价由“差距悬殊”变为“相对合理”;总体公交不平等的主要来源为群组内不平等 且贡献率在10~40 min时逐渐下降,在50~90 min时逐渐上升。研究表明,不同时间阈值会使公交 不平等评价结果出现偏差甚至得到相反的结论,有必要进一步研究消除时间阈值影响的方法。     

基于混合算法的联合运输路径优化

为了求解联合运输网络的最优运输方式组合问题,采用遗传算法并使用整数编码方式对城市节点进行编码,摒弃了传统的二进制编码方式,有效地缩减了编码长度并简化了编解码工作;城市节点链的运输方式组合与节点间运输方式转换使用动态规划方法来确定;至于联合运输网络数据,在建立多重图数据结构基础上,采用结构体数组与链式存储结构相结合的方式来存储。通过仿真实验表明,该方法可行,能够在较短的时间和可预期的迭代次数内找到最优解。      

交通领域碳足迹研究综述

气候变化问题引起了全球的高度重视,碳减排和碳循环得到了广泛关注.碳足迹的研究就是在全球气候变暖的背景下提出,它是节能减排的基本量化参数.在碳足迹研究的基础上,对交通领域碳足迹进行专项研究,了解交通领域实现低碳化的潜力和主要影响因素,有利于实现交通领域的节能减排,对实现交通与环境的和谐具有重要作用.文中回顾了交通领域的碳足迹的主要研究,介绍了碳足迹的定义、计算方法以及国内外交通领域现有的研究成果,并对国内外研究进行比较分析,针对我国目前交通碳足迹研究现状和存在的问题,确定进一步的发展方向.目前国内外关于交通领域的碳足迹研究都只是关注交通活动的某一方面,在对碳足迹进行研究时,应扩大研究范围,从多个角度进行,并开拓新的研究方向.      

公共白行车租赁站点调度需求量模型研究

为降低城市公共自行车调度过程中调度员凭经验确定各站点调度需求量的盲目性,提高调度科学性并缩减调度时间和成本,将城市公共自行车租赁站点调度需求量模型描述为最优化整数规划问题,考虑系统的稳定性和调度触发时间,以高峰时段系统的整体稳定性最强、调度启动时间最晚为目标建立公共自行车租赁站点调度需求量模型.针对该模型特点设计了十进制编码、二人竞赛选择、算术交叉、非均匀变异的遗传算法对模型进行求解.通过调度实例验证模型和算法的可行性,得到各租赁站点的最优调度需求量.结果表明,按照该模型求解出的调度需求量进行调度能够延迟高峰时段的调度启动时间至1.33h,较站点均一化存放率调度延迟0.67h,极大地延缓了调度启动时间并缩减调度工作量.