考虑容量限制的多公交车型运行计划优化模型

车容量限制是公交运行计划编制的重要约束.以单条公交线为研究对象,综合考虑了不同公交车型的技术经济性能、车容量大小、车辆数限制和客流需求的时变特征等因素,建立同步优化公交车型和时刻表的规划模型,以确定线路的发车时刻表和选择车型的最优组合.建立了以公交企业运营成本和公交乘客出行成本最小为目标,带有0-1决策变量的非线性整数规划模型,针对该模型多目标函数的求解特点,采用枚举法求解每辆车的发车时刻,应用遗传算法求解车型选择的序列.最后以北京市某公交线为案例进行分析,优化后的发车时刻表和车型配置方案具有较好的运营效果.算例结果表明,采用多车型方案较传统的单一车型方案更具经济性,乘客的出行成本可减少13.9%,企业的运营成本可减少3.5%.     

基于换乘站停站时间延长的城市轨道交通末班车时刻表优化

在城市轨道交通网络中,提高末班车乘客换乘成功性对其夜间出行有重要意义.通过压缩末班车区间运行时间与非换乘站停站时间,延长换乘站停站时间,建立以换乘成功客流量最大为目标的时刻表优化模型,实现末班车双向衔接成功.将模型刻画为混合整数线性规划问题,通过对模型简化,利用CPLEX分支切割算法进行求解.最后,以武汉地铁网络为案例,验证模型的有效性.结果表明,模型可利用CPLEX快速求得精确解.末班车停站时间延长可有效提高末班车间换乘衔接成功性;在末班车收车时间可推迟情形下,推迟收车时间可进一步提升末班车换乘效果.     

基于站外限流与时刻表调整的地铁换乘站大客流协同控制

针对高峰期地铁换乘站站台容易发生拥挤问题,在分析乘客进站及换乘走行过程的基础上,构建了站外限流与列车时刻表协同优化模型。该模型可在满足站台安全容量约束下尽可能降低站外限流率,实现站外站内乘客加权人均等待时间最小。采用混沌遗传算法求解模型,并以惠新西街南口站为例,对本文模型、优化前方案和既有只限流方法进行对比分析。结果表明:与优化前方案相比,模型所得方案可满足站台安全容量约束,加权人均等待时分减少了21.2%;与只限流方法相比,模型可使站外平均限流率从36%下降到7.3%,加权人均等待时分减少了43.8%,且模型方案的各项指标在乘客走行时分发生波动的情形下表现更稳定。     

Hydrodynamic experiment of submerged floating tunnel under regular wave and current actions during construction period

Submerged floating tunnel (SFT) is an innovative cable-supported structural system for crossing deep and long-distance ocean environments. In the complex ocean environment, the construction of SFT needs to consider wave and current forces. Specific construction measures and control also require in-depth study and understanding of the dynamic response of SFT under such environmental loads. In this study, the dynamic response of SFT and cable forces under the action of waves alone and wave-current interactions are investigated by using a large wave-current basin. A total of 138 regular wave and wave-current cases were conducted during the experiments, and the influence of waves and wave-current interactions on the dynamic response of SFT and cable forces are discussed in detail by combining experimental data with corresponding analysis. Results show that the wave height, current velocity, and ratio of wavelength to structure size are important factors affecting the dynamic response of SFT and cable forces. The multi-anchor cable arrangement used in the present experimental tests distribute cable force more effectively and reduce the potential safety hazard caused by cable breakage. This study can provide a useful reference for the construction and control of the single SFT segment under construction in a complex ocean environment, especially under the interaction of waves and currents.     

Robust stop-skipping patterns in urban railway operations under traffic alteration situation

In this paper an operation mode which is based on the stop-skipping approach is studied in urban railway lines under uncertainty. In this mode, each train follows a specific stop schedule. Trains are allowed to skip any intermediate stations to increase the commercial speed and to save energy consumption. As the commercial speed increases, the number of required trains in operation reduces and results eliminating unnecessary costs. To that end, a new mathematical model is proposed to reach the optimum stop schedule patterns. In the planning step, based on the traffic studies, the headway distributions are computed for different weekdays, and holidays. However, in practice, because of many unexpected events, the traffic may alter from what is planned. Therefore, in this condition, a robust plan is required that is optimized and immunized from uncertainty. In this paper, a new robust mathematical model, as well as two heuristic algorithms including (1) a decomposition-based algorithm and (2) a Simulated Annealing (SA) based algorithm is proposed. Finally, an Iranian metro line is studied and the optimum patterns are presented and analyzed.     

A stochastic optimization model for transit network timetable design to mitigate the randomness of traveling time by adding slack time

Transit network timetabling aims at determining the departure time of each trip of all lines in order to facilitate passengers transferring either to or from a bus. In this paper, we consider a bus timetabling problem with stochastic travel times (BTP-STT). Slack time is added into timetable to mitigate the randomness in bus travel times. We then develop a stochastic integer programming model for the BTP-STT to minimize the total waiting time cost for three types of passengers (i.e., transferring passengers, boarding passengers and through passengers). The mathematical properties of the model are characterized. Due to its computational complexity, a genetic algorithm with local search (GALS) is designed to solve our proposed model (OPM). The numerical results based on a small bus network show that the timetable obtained from OPM reduces the total waiting time cost by an average of 9.5%, when it is tested in different scenarios. OPM is relatively effective if the ratio of the number of through passengers to the number of transferring passengers is not larger than a threshold (e.g., 10 in our case). In addition, we test different scale instances randomly generated in a practical setting to further verify the effectiveness of OPM and GALS. We also find that adding slack time into timetable greatly benefits transferring passengers by reducing the rate of transferring failure.     

基于规则格网公路DEM精度分析

简述了规则格网DEM的精度影响因素,重点讨论了规则格网DEM精度的理论模型(Li,1993b),利用数字地面模型完成了武汉新洲凤刘连接线路线设计,对精度进行了预测,并与实际统计结果进行了分析。     

The multi-objective railway timetable rescheduling problem

Unexpected disruptions occur for many reasons in railway networks and cause delays, cancelations, and, eventually, passenger inconvenience. This research focuses on the railway timetable rescheduling problem from a macroscopic point of view in case of large disruptions. The originality of our approach is to integrate three objectives to generate a disposition timetable: the passenger satisfaction, the operational costs and the deviation from the undisrupted timetable. We formulate the problem as an Integer Linear Program that optimizes the first objective and includes $\epsilon$-constraints for the two other ones. By solving the problem for different values of $\epsilon$, the three-dimensional Pareto frontier can be explored to understand the trade-offs among the three objectives. The model includes measures such as canceling, delaying or rerouting the trains of the undisrupted timetable, as well as scheduling emergency trains. Furthermore, passenger flows are adapted dynamically to the new timetable. Computational experiments are performed on a realistic case study based on a heavily used part of the Dutch railway network. The model is able to find optimal solutions in reasonable computational times. The results provide evidence that adopting a demand-oriented approach for the management of disruptions not only is possible, but may lead to significant improvement in passenger satisfaction, associated with a low operational cost of the disposition timetable.     

地铁综合监控系统中的环境监控系统时间表实现方法

阐述了地铁综合监控系统软件平台中的BAS(环境监控系统)时间表功能,以及综合监控和环境监控系统联合实现BAS时间表的方法。BAS时间表是地铁环控系统的主要功能之一,能够灵活编排的BAS时间表,为运营单位提供了便捷的操作方法。     

结合列车时间表的地铁换乘同步性优化

既有开行方案的调度编排理论较少考虑换乘客流的协调同步性和列车承载能力,本文提出基于列车时刻的地铁换乘同步性优化模型,其特点是根据不同客流量的到达规律和接驳列车容量限制,以接驳列车为实时追踪对象,将离散客流准确地划分到有效时间域内,并将客流拥挤情况和换乘线时刻表协调问题考虑到优化模型中。