Safety of the express freight train running over a long-span bridge

Purpose-Express freight transportation is in rapid development currently.Owing to the higher speed of express freight train,the deformation of the bridge deck worsens the railway line condition under the action of wind and train moving load when the train runs over a long-span bridge.Besides,the blunt car body of vehicle has poor aerodynamic characteristics,bringing a greater challenge on the running stability in the crosswind.Design/methodology/approach-In this study,the aerodynamic force coefficients of express freight vehicles on the bridge are measured by scale model wind tunnel test.The dynamic model of the train-long-span steel truss bridge coupling system is established,and the dynamic response as well as the running safety of vehicle are evaluated.Findings-The results show that wind speed has a significant influence on running safety,which is mainly reflected in the over-limitation of wheel unloading rate.The wind speed limit decreases with train speed,and it reduces to 18.83 m/s when the train speed is 160 km/h.Originality/value-This study deepens the theoretical understanding of the interaction between vehicles and bridges and proposes new methods for analyzing similar engineering problems.It also provides a new theoretical basis for the safety assessment of express freight trains.

Simulation study on the influence of longitudinal dynamic force on extreme-long heavy-haul trains

Purpose–The objective of this study is to investigate the impact of longitudinal forces on extreme-long heavy-haul trains,providing new insights and methods for their design and operation,thereby enhancing safety,operational efficiency and track system design.Design/methodology/approach–A longitudinal dynamics simulation model of the super long heavy haul train was established and verified by the braking test data of 30,000 t heavy-haul combination train on the long and steep down grade of Daqing Line.The simulation model was used to analyze the influence of factors on the longitudinal force of super long heavy haul train.Findings–Under normal conditions,the formation length of extreme-long heavy-haul combined train has a small effect on the maximum longitudinal coupler force under full service braking and emergency braking on the straight line.The slope difference of the long and steep down grade has a great impact on the maximum longitudinal coupler force of the extreme-long heavy-haul trains.Under the condition that the longitudinal force does not exceed the safety limit of 2,250 kN under full service braking at the speed of 60 km/h the maximum allowable slope difference of long and steep down grade for 40,000 t super long heavy-haul combined trains is 13‰,and that of 100,000 t is only 5‰.Originality/value–The results will provide important theoretical basis and practical guidance for further improving the transportation efficiency and safety of extreme-long heavy-haul trains.

Monitoring energy usage of heavy-haul iron ore trains with on-board energy meter for improving energy efficiency

Purpose-For billing purposes,heavy-haul locomotives in Sweden are equipped with on-board energy meters,which can record several parameters,e.g.,used energy,regenerated energy,speed and position.Since there is a strong demand for improving energy efficiency in Sweden,data from the energy meters can be used to obtain a better understanding of the detailed energy usage of heavy-haul trains and identify potential for future improvements.Design/methodology/approach-To monitor energy efficiency,the present study,therefore,develops key performance indicators(KPIs),which can be calculated with energy meter data to reflect the energy efficiency of heavy-haul trains in operation.Energy meter data of IORE class locomotives,hauling highly uniform 30-tonne axle load trains with 68 wagons,together with additional data sources,are analysed to identify significant parameters for describing driver influence on energy usage.Findings-Results show that driver behaviour varies significantly and has the single largest influence on energy usage.Furthermore,parametric studies are performed with help of simulation to identify the influence of different operational and rolling stock conditions,e.g.,axle loads and number of wagons,on energy usage.Originality/value-Based on the parametric studies,some operational parameters which have significant impact on energy efficiency are found and then the KPIs are derived.In the end,some possible measures for improving energy performance in heavy-haul operations are given.

Dynamic effect of heavy-haul train on seismic response of railway cable-stayed bridge

This paper focuses on understanding and evaluating the dynamic effect of the heavy-haul train system on the seismic performance of a long-span railway bridge. A systematic study on the effect of heavy-haul trains on bridge seismic response has been conducted, considering the influence of vehicle modeling strategies and dynamic characteristics of the seismic waves. For this purpose, the performance of a long-span cable-stayed railway bridge is assessed with stationary trains atop it, where the heavy-haul vehicles are modeled in two different ways: the multi-rigid body model with suspension system and additional mass model. Comparison of the bridge response in the presence or absence of the train system has been conducted, and the vehicle loading situation, which includes full-load and no-load, is also discussed. The result shows that during the earthquake, the peak moment of the main girder and peak stress of stay cables increase by 80% and by 40% in the presence of fully loaded heavy-haul trains, respectively. At the same time, a considerable decrease appears in the peak acceleration of the main girder. This proves the existence of the damping effect of the heavy-haul train system, and this effect is more obvious for the fully loaded vehicles. Finally, this paper proposes an efficient vehicle modeling method with 2 degrees of freedom(DOF) for simplifying the treatment of the train system in bridge seismic checking.

Dynamic performance of heavy-haul combined train applying emergency braking on straight line

A heavy-haul train-track coupled model is developed. Taking the emergency braking of the 2×104 t combined train as example, the train longitudinal impulse, the coupler dynamic behaviors and wheel-rail interactions of vehicles distributing in the different positions are analyzed. The results indicate that under the coupler compressing forces, the couplers of middle locomotives may tilt to the free swing limits, which induces the unidirectional tilt of their connected wagon couplers. Consequently, the coupler longitudinal forces produce the lateral components, and then affect the wheel-rail dynamic interaction. The performance of the middle locomotive and their neighboring freight wagons deteriorate significantly, becoming the most dangerous parts in the combined train. The wagons disconnecting with the locomotives can basically keep their couplers to stabilize in the centering positions, even though the maximum coupler longitudinal force acts on it. And its corresponding running safety also has little changes.

System integration and innovation of operating 20 kt combined heavy-haul train on Datong-Qinhuangdao line

Datong-Qinhuangdao line, as the first electrified double-track heavy-haul line dedicated to coal transport in China, extends from Datong in the west, and reaches Qinhuangdao in the east, opened to traffic in December, 1992, totaling 653 km with the designed annual traffic volume of 1×108 t. In order to meet the demands of national economic development, the transport capacity of the line must be enhanced greatly. Depending on independent innovation, MOR, for the first time in the world,realizes the integration between GSM-R and Locotrol, the integration between 800 MHz digital radio and Locotrol, and the integration between a single set of Locotrol and SS4 locomotive. Meanwhile, CR develops equipment portfolio for heavy-haul through combining 2 high power locomotives of HXD series (means harmony) with controllable EOT. Relying on integration and innovation, it succeeds in operating 20 kt-level combined heavy-haul train on Datong-Qinhuangdao line, which tripled the annual traffic volume of the line from 1×108 t in 2002 to 3×108 t in 2007.

Research on Optimization of Freight Train ATO Based on Elite Competition Multi-Objective Particle Swarm Optimization

In view of the complex problems that freight train ATO (automatic train operation) needs to comprehensively consider punctuality, energy saving and safety, a dynamics model of the freight train operation process is established based on the safety and the freight train dynamics model in the process of its operation. The algorithm of combining elite competition strategy with multi-objective particle swarm optimization technology is introduced, and the winning particles are obtained through the competition between two elite particles to guide the update of other particles, so as to balance the convergence and distribution of multi-objective particle swarm optimization. The performance comparison experimental results verify the superiority of the proposed algorithm. The simulation experiments of the actual line verify the feasibility of the model and the effectiveness of the proposed algorithm.

China-Europe Freight Train Promotes Bilateral Trade

On October 8,the'Belt and Road'Leading Group office published the'ChinaEurope Freight Train Development Plan',which is a fiveyear plan in accordance with China’s13th'Five-Year Plan'.The document formulated the major tasks for the construction of China-Europe freight train project for the next five years,and clarified three space layouts,including the China-Europe

An Algorithm for the Optimal Matching Speeds of Pass enger and Freight Trains in Mixed Operations

This paper models the calculation of the optimal matching speeds of passenger and freight trains with various stage control methods for speed in mixed operations, presents a algorithm for the solution and justifies it with a practical example.

Wheel Profile Optimization of Speed-up Freight Train Based on Multi-population Genetic Algorithm

The geometric shape of the wheel tread is mathematically expressed,and geometric parameters affecting the shape of the wheel were extracted as design variables.The vehicle dynamics simulation model was established based on the vehicle suspension parameters and track conditions of the actual operation,and the comprehensive dynamic parameters of the vehicle were taken as the design objectives.The matching performance of the wheel equivalent conicity with the vehicle and track parameters was discussed,and the best equivalent conicity was determined as the constraint condition of the optimization problem;a numerical calculation program is written to solve the optimization model based on a multi-population genetic algorithm.The results show that the algorithm has a fast calculation speed and good convergence.Compared with the LM profile,the two optimized profiles effectively reduce the wheelset acceleration and improve the lateral stability of the bogie and vehicle stability during straight running.Due to the optimized profile increases the equivalent conicity under larger lateral displacement of the wheelset,the lateral wheel-rail force,derailment coefficient,wheel load reduction rate,and wear index are reduced when the train passes through the curve line.This paper provides a feasible way to ensure the speed-up operation of a freight train.

A review on design and testing methodologies of modern freight train draft gear system

Rolling stock connection systems are key to running longer and heavier trains as they provide both the connections of vehicles and the damping,providing the longitudinal suspension of the train.This paper focuses on the evolution of both connection and stiffness damping systems.Focus is on freight rolling stock,but passenger draw gears are also examined.It was found that connection systems have evolved from the buff and chain system used in the pioneer railways of the 1800s to the modern auto-coupler connection systems that are in-service worldwide today.Refined versions of the buff and chain coupling are,however,still in use in the EU,UK,South America and India.A wide range of auto-coupler systems are currently utilised,but the AAR coupler(Janney coupler)remains the most popular.A further variation that persists is the SA3 coupler(improved Wilson coupler)which is an alternative auto-coupler design used mainly throughout the former Soviet Union.Restricting the review to auto-coupler systems allowed the paper to focus on draft gears which revealed polymer,polymer-friction,steel spring-friction,hydraulic draft gears and sliding sill cushioning systems.Along with the single compressive draft gear units balanced and floating plate configurations are also presented.Typical draft gear acceptance standards are presented along with modelling that was included to aid in presentation of the functional characteristics of draft gears.

Theoretical and Experimental Study on The Speed-up of Freight Train with Mixed Marshaling of Light and Heavy Vehicle

To study the influence of the speed-up of a freight train with mixed marshaling of light and heavy vehicles on the dynamic behavior,a dynamic model of the freight train was established based on the modular method of cyclic variables,and the dynamic behavior of the freight train was simulated and analyzed under different marshaling patterns,speeds and line conditions.On-site speed-up test with different marshaling freight trains was carried out,and the stability and ride-index of the train before and after the speed-up were compared and analyzed.The feasibility of increasing the speed of freight trains with mixed marshaling of light and heavy cars was demonstrated theoretically and experimentally.The results show that the theory is in good agreement with the test,which can effectively reflect the dynamic behavior of the vehicle.The dynamic behavior of the freight train in the study meets the requirements of increasing speed to 90 km/h.This paper provides a theoretical basis and method for railway freight transportation and the speed-up of freight vehicles.

基于多目标进化的超限超重货物运输专列路径优化方法

针对超限超重货物运输专列路径优化问题,引入限界改造和桥梁加固要素,以铁路运能损失、运输时间和运输费用的最小化为优化目标,构建铁路超限超重货物运输专列路径优化模型;考虑专列同时运送多件超限超重货物的特点,设计货物综合投影算法,并以Pareto支配关系框架下的NSGA-Ⅱ多目标进化算法为基础,结合基于移动不可行解的自适应惩罚函数的约束处理技术及超限超重货物运输专列开行特征,提出一种基于多目标进化的铁路超限超重货物运输专列路径优化算法。实例分析结果表明:该方法能高效合理地处理路径优化任务中的多个目标;与常用的3种约束多目标算法相比,设计的优化算法能使计算耗时降低0.24%~29.94%、超体积指标值提高4.25%~13.11%,并得到一组收敛性和多样性更好的相对最优方案。该方法克服了传统专列路径优化中单纯依靠经验或从备选方案中择优的弊端,可为铁路超限超重货物运输专列路径决策提供技术支持。

基于一维AlexNet卷积神经网络的铁路货车轴承故障识别

铁路货车是我国货物运输的一种重要交通工具,轮对及滚动轴承是铁路货车的关键部件之一,与其他普通轴承相比,铁路货车轴承由于结构复杂、承载力大、故障特征频率难于精确计算,一般基于信号处理的特征提取加分类器的传统智能诊断算法,对专家经验要求高。在此基于AlexNet神经网络,提出基于改进一维卷积神经网络智能诊断模型,通过引用改进的卷积核增强神经网络的非线性表达能力。以353130B铁路货车轴承为研究对象,使用实验室轴承实验机分别对正常轴承、外圈故障、内圈故障、滚子故障4种类型信号进行采集识别研究,研究结果显示该网络对轴承故障的识别率可达99%,具有优秀的故障识别特性,表明该模型具备良好的泛化价值,对铁路货车轴承故障识别检测有重要的研究价值。

关于打通铁路网运输能力堵点对策探究

国铁企业落实党中央部署要求并加快推进铁路货运市场化改革,采取有效措施尽快打通铁路网运输能力堵点,有效降低物流成本。通过分析路网总体规模、旅客运输供给能力、货物运输保障能力等铁路网运输能力现状,剖析铁路网运输能力堵点及成因。在此基础上,提出加强铁路网运输能力经验借鉴,探析打通铁路网运输能力堵点对策,即:畅通普速干线通道,加强煤运通道能力保障,强化中欧班列通道能力,完善港口铁路通过能力,增强西部陆海新通道线路能力,完善枢纽点线配套能力,强化铁路货运设施设备卸车能力等方面,在助力降低全社会物流成本中发挥“火车头”的重要作用。

贸易便利化与沿线城市产业结构升级——基于中欧班列的准自然实验

中欧班列的国际货运属性导致其对中国贸易便利化和技术创新的影响有别于一般国内铁路。基于2004—2021年中国地级市的数据,将中欧班列开通视为“准自然实验”,运用多期双重差分法探究贸易便利化对沿线城市产业结构升级的影响。结果显示:第一,中欧班列开通能够推动沿线城市产业结构朝着高级化方向发展,在进行三种稳健性检验后结果仍然显著。第二,技术创新、融资支持和数字智能三种机制能对开通城市的产业结构升级产生显著的正向影响。第三,中欧班列对沿线城市产业结构升级的推动作用主要存在于非中心城市。未来城市应利用贸易便利化这一有力“引擎”,通过提升融资便利与数字智能水平,充分发挥交通基础设施在促进创新要素流动中的作用,为沿线城市产业结构调整提供支撑。

基于PSENet区域分割的列车车厢号定位研究

针对自然场景中行驶列车的车厢号采用现有文本定位方法容易存在严重畸变,从而导致漏检率高的问题,提出一种基于区域分割的列车车厢号精确定位方法。该方法所采用的网络模型基于PSENet,首先采用引入通道域注意力的ResNet50网络提取特征,使模型更加关注卷积通道信息,从通道域的角度对权重进行再分配,提高车厢号的定位精度;然后采用特征金字塔和自底向上路径增强模块融合多尺度特征图,将浅层网络中的强定位特征传播到深层网络,以从复杂环境中准确定位车厢号区域,降低车厢号的漏检率;最后采用基于广度优先算法的渐进尺度扩展模块对融合的特征图进行目标区域的从小尺度到大尺度的拓展分割,使用结合集合相似度度量Dice系数的损失函数对分割结果进行分类回归,输出定位结果。实验结果表明:通过在真实列车车厢号图像数据集上进行训练验证,本文提出的网络模型在铁路货运列车车厢号定位精度达到97.47%,召回率为94.14%,综合F1分数为95.78%,预测单张图约需0.2 s。相比于基础PSENet对车厢号的定位精确率提升3.78%,召回率提升1.71%,总体上车厢号的F1分数提升2.73%。研究成果可为列车车厢号自动检测识别系统提供一种高精度的车厢号检测定位方法。

基于级联干扰观测器的货运列车分布式控制研究

针对货运列车在多源扰动下的跟踪控制问题,提出一种基于级联干扰观测器的固定时间替换滑模控制方法。首先构建了考虑车间作用力的多质点动力学模型,针对匹配与非匹配扰动同时存在的情形,设计了一种级联结构扰动观测器同时估计多源扰动,放宽了传统扰动观测器要求“扰动缓慢变化”的前提条件。基于扰动观测信息,将非匹配扰动下的列车动力学模型转化为匹配模式。最终,提出了一种基于替代滑模法的分布式控制策略。仿真结果表明,所提的级联干扰观测器能够在0.5 s内准确估计多源干扰;相比于传统的列车跟踪控制研究,所提出的控制策略能够在快速处理多源扰动带来的一系列失稳问题,在保障车间作用力稳定的同时,实现了速度-位移双指标鲁棒跟踪控制;相对于传统控制方法系统收敛时间提高5 s以上,体现了较好的实时性与鲁棒性。

面向实时需求的高铁快运列车运输组织方案协同优化研究

近年来,我国电商行业高速发展,快递需求随之快速增长。高铁快运凭借其运量大、速度快、能耗低的特点,成为现代快递运输的重要方式。在保证高铁快运产品时效性的基础上,为解决现阶段我国高铁快运列车时刻表、停站方案与货物装配方案三者协同优化研究不足而导致的高铁运力资源利用效率较低的问题,建立二次0-1混合整数规划模型。借鉴铁路阶段计划的思想,将全天分为多个时段,以每个时段的货运需求为导向,针对下个时段的高铁快运货物装配方案和新增快运列车停站方案和时刻表进行协同优化。针对已知新增快运列车数量的情况,建立了考虑货物时效性的新增列车的停站方案、时刻表和装配方案协同优化模型(简称协同优化模型)。针对模型约束进行线性化处理,并根据模型特点设计并使用两阶段求解方法,利用LINGO软件求解。以宁杭高铁线路为例,针对9:00-12:00的列车运行图进行优化分析。从结果来看,协同优化模型相比于传统优化方法,可以同时减少列车在途时间和货物在途时间,保证运力资源的充分利用。对比两阶段求解的求解结果可以发现,相比第1阶段,第2阶段得到的货物在途时间更短,货物装配方案更合理,由此可见两阶段求解方法也是合理且有效的。研究结果可以为进一步优化高铁快运列车运输组织方案,提高运输效率提供参考。

双线束铁路集装箱中心站“列车-轨道”分配策略研究

为了满足铁路集装箱中心站日益增长的作业需求,部分中心站已建成或规划在建第二线束,多线束的建设会大幅提升中心站的作业能力,但相应的也可能会产生线束间的作业均衡和集装箱的场内转运问题。以最小化线束间轨道门吊的工作量差异和集装箱场内转运数量为目标,考虑轨道的时空容量、列车的进出站时间要求及装卸作业要求等约束以保证列车按时完成作业,建立双目标整数规划模型来研究双线束集装箱中心站内的“列车-轨道”分配问题。设计启发式规则生成初始可行解,并利用存档式多目标模拟退火算法处理双目标优化问题,以得到一组帕累托近似最优解。设计算例验证了算法的可行性和有效性,并研究了装卸线的数量和轨道门吊的配置对实验结果的影响。结果表明:本文提出的双线束铁路集装箱中心站“列车-轨道”分配策略能够有效均衡线束间的工作量并降低集装箱场内转运数,灵敏度分析结果能够为未来双线束集装箱中心站的规划建设提供借鉴。