Analyzing the gap between the QOS demanded by PT users and QOS supplied by service operators

This research evaluated the effectiveness of tendered bus public transportation (PT) in improving the attractiveness of that service in order to promote sustainable mobility. This was accomplished by characterizing the gap between the quality of service (QOS) supplied by contract regimes and that which is demanded by passengers. Analysis of a customer satisfaction survey aimed at bus users provided insight into their ranking of 14 QOS parameters while 13 active service contracts were analyzed for their impact on QOS. In-depth interviews with relevant experts completed the complex narrative that is Israel’s policy of privatization in PT. Both qualitative and quantitative analyses helped identify those QOS parameters most in demand by passengers and impacted by contracts. The results show that the gap is minimal, high demand parameters receive increased priority in contracts. In addition this research documented an evolution in the method contracts employed to provide QOS. Late model contracts define an increasingly higher minimum QOS; but also strongly limit the operator’s ability to make service changes. This is a trend which should improve QOS in Israel but reduce the incentive for operator enacted QOS initiatives. Despite its obvious success to date, it might be time to change again the contract regime for the provision of competitive bus services in Israel.     

Understanding the distribution characteristics of bus speed based on geocoded data

Data-driven traffic management and control has attracted much attention recently. This paper conducts a series of coherent analyses based on geocoded data to understand the distribution characteristics of bus operational speed and to explore the potential applications of speed distributions. First, an original bipartite model is adopted for capturing instantaneous speed where the suspended and moving states are considered separately and a two-component mixed Weibull distribution is used to model the speed distribution in moving states. The mixed Gaussian distribution with variable components is found to be capable of expressing the speed distribution patterns of different road sections. Second, elaborate analyses on the basis of speed distribution modelling are conducted: (i) regression analyses are conducted to explore the correlations between parameters of instantaneous speed distributions and traffic related factors; (ii) a powerful clustering method using Kullback-Leibler divergence as the distance measure is proposed to grade the road sections of a bus route. These results can be utilized in fields such as bus operations management, bus priority signal control and infrastructure transformation aiming to improve the efficiency of bus operations systems.     

A European vision for more environmentally friendly buses

This paper deals with EBSF – European Bus System of the Future, 3iBS – the Intelligent, Innovative Integrated Bus Systems and ZeEUS – Zero Emission bUs Systems, three research projects funded by the European Commission, with the aim to develop a new generation of buses. The common task is to develop innovative solutions to increase the attractiveness of this mode and to operate more environmentally-friendly vehicles.Key working areas are more comfortable layouts, advanced ITS-based solutions to improve operations, new engines designed to save fuel and the enhancement of the electric option. Concern for the environment lies behind the majority of these innovations. The innovations are tested in real urban environments and performance assessed through Key Performance Indicators. Within EBSF it was also possible to perform a Transferability Exercise (TE) to assess the theoretical exportability of the innovations to more urban contexts.The research objective of this paper is to critically revise the projects’ results and present them for further applications beyond the European projects field. Results thus far stressed contrasting aspects within a common vision for the development of a new generation of buses. Stakeholders are well aware of the need to comply with the European standards in the field of sustainable mobility. This is shown by the fact that the majority of them are becoming more environmentally aware about the need to renew their fleets. However, because of economical reasons they fail to consider any environmental concerns in the TE, even when these should be crucial in the transfer decisions.     

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.     

Optimally combined headway and timetable reliable public transport system

This paper presents a model-based multiobjective control strategy to reduce bus bunching and hence improve public transport reliability. Our goal is twofold. First, we define a proper model, consisting of multiple static and dynamic components. Bus-following model captures the longitudinal dynamics taking into account the interaction with the surrounding traffic. Furthermore, bus stop operations are modeled to estimate dwell time. Second, a shrinking horizon model predictive controller (MPC) is proposed for solving bus bunching problems. The model is able to predict short time-space behavior of public transport buses enabling constrained, finite horizon, optimal control solution to ensure homogeneity of service both in time and space. In this line, the goal with the selected rolling horizon control scheme is to choose a proper velocity profile for the public transport bus such that it keeps both timetable schedule and a desired headway from the bus in front of it (leading bus). The control strategy predicts the arrival time at a bus stop using a passenger arrival and dwell time model. In this vein, the receding horizon model predictive controller calculates an optimal velocity profile based on its current position and desired arrival time. Four different weighting strategies are proposed to test (i) timetable only, (ii) headway only, (iii) balanced timetable - headway tracking and (iv) adaptive control with varying weights. The controller is tested in a high fidelity traffic simulator with realistic scenarios. The behavior of the system is analyzed by considering extreme disturbances. Finally, the existence of a Pareto front between these two objectives is also demonstrated.     

Integrated optimization of transit priority operation at isolated intersections: A person-capacity-based approach

In this paper, a person-capacity-based optimization method for the integrated design of lane markings, exclusive bus lanes, and passive bus priority signal settings for isolated intersections is developed. Two traffic modes, passenger cars and buses, have been considered in a unified framework. Person capacity maximization has been used as an objective for the integrated optimization method. This problem has been formulated as a Binary Mixed Integer Linear Program (BMILP) that can be solved by a standard branch-and-bound routine. Variables including, allocation of lanes for different passenger car movements (e.g., left turn lanes or right turn lanes), exclusive bus lanes, and passive bus priority signal timings can be optimized simultaneously by the proposed model. A set of constraints have been set up to ensure feasibility and safety of the resulting optimal lane markings and signal settings. Numerical examples and simulation results have been provided to demonstrate the effectiveness of the proposed person-capacity-based optimization method. The results of extensive sensitivity analyses of the bus ratio, bus occupancy, and maximum degree of saturation of exclusive bus lanes have been presented to show the performance and applicable domain of the proposed model under different composition of inputs.     

客车结构杆连接的真实形状对结构计算的影响

本文应用有限元分析法，研究了承载式客车底加中４种基本结构的杆连接的真实形状对结构扭转变形和应力计算的影响。     

客车车身蒙皮的预应力张拉工艺

介绍了客车预应力蒙皮的张拉工艺及其在丹东汽车制造厂的应用情况。采用整张预应力张拉蒙皮，可使客车外蒙皮产生一定的内应力，使其蒙皮表面绷紧，平整光滑，流畅美观；同时可消除客车行驶过程中蒙皮产生振颤噪声和鼓动声，使乘客乘坐舒适。     

大型客车车外噪声测试分析与控制

对大型豪华客车的车外噪声进行了研究，用声强法对车外噪声的主要声源进行了鉴别。对发动机及辅助装备的工作室声学特性进行了测试分析，提出了控制车外噪声的相应策略，并作了遮蔽发动机噪声的模拟试验。     

波哥大市快速公交系统建设经验

南美洲国家哥伦比亚的首都波哥大曾以交通严重堵塞、城市环境恶化而著名,被认为是一个几乎没有希望的城市.从1998年开始,波哥大实行全新的交通改革策略.3年后,它完全改变了对大众运输系统的传统观感,成功建立了一套具有特色的快速公交系统,为全球树立了城市快速公交的"波哥大模式".