Optimization study of station track utilization in high-speed railroad based on constraints of control in random origin and process

Purpose-The purpose of this paper is to eliminate the fluctuations in train arrival and departure times caused by skewed distributions in interval operation times.These fluctuations arise from random origin and process factors during interval operations and can accumulate over multiple intervals.The aim is to enhance the robustness of high-speed rail station arrival and departure track utilization schemes.Design/methodologylapproach-To achieve this objective,the paper simulates actual train operations,incorporating the fluctuations in interval operation times into the utilization of arrival and departure tracks at the station.The Monte Carlo simulation method is adopted to solve this problem.This approach transforms a nonlinear model,which includes constraints from probability distribution functions and is difficult to solve directly,into a linear programming model that is easier to handle.The method then linearly weights two objectives to optimize the solution.Findings-Through the application of Monte Carlo simulation,the study successfully converts the complex nonlinear model with probability distribution function constraints into a manageable linear programming model.By continuously adjusting the weighting coefficients of the linear objectives,the method is able to optimize the Pareto solution.Notably,this approach does not require extensive scene data to obtain a satisfactory Pareto solution set.Originality/value-The paper contributes to the field by introducing a novel method for optimizing high-speed rail station arrival and departure track utilization in the presence of fluctuations in interval operation times.The use of Monte Carlo simulation to transform the problem into a tractable linear programming model represents a significant advancement.Furthermore,the method's ability to produce satisfactory Pareto solutions without relying on extensive data sets adds to its practical value and applicability in real-world scenarios.

Heavy Metal Pollution in Soils on Railroad Side of Zhengzhou-Putian Section of Longxi-Haizhou Railroad, China

The pollution status and horizontal distribution of heavy metals (Ni, Pb, Cr, Zn, Cu, and Cd) in the soil on railroad side along the Zhengzhou-Putian section of Longxi-Haizhou Railroad were studied by collecting soil samples along a sampling section perpendicular to the railroad at the distances of 0, 10, 20, 30, 50, 100, 200, 300, and 500 m from the railroad edge. The concentrations of heavy metals in the sampling soils were higher than those of the control site. The concentrations of Pb, Zn, and Cd were found to be the highest in the soils at the railroad edge, and then decreased with increasing distance from the railroad. The highest concentrations of Ni, Cr, and Cu in soils were located at about 10-30 m from the railroad. Compared with the single factor pollution index (SFPI) of heavy metals calculated for the control site, the average SFPI from the sampling sites decreased in the order of Cr > Cd > Pb > Zn > Ni > Cu. There were notable negative correlations between the integral pollution index (IPI) of soil heavy metals at all sampling sites and the distances from the railroad. According to three IPIs calculated from the background values of heavy metals in och-aquic Cambisols, the heavy metal concentrations in the control soil, and the 2nd levels for soil heavy metals in GB15618-1995, the study area could be divided, based on the distances from the railroad, into four pollution zones: heavy pollution zone (0-10 m), medium pollution zone (10-50 m), slight pollution zone (50-100 m), and warning zone (100-500 m), respectively.

Pendulum systems for harvesting vibration energy from railroad tracks and sleepers during the passage of a high-speed train: A feasibility evaluation

We evaluate the feasibility of recovering energy from the vibrations of track and sleepers,during passage of a high-speed train,by means of a pendulum harvester.A simple mathematical model of the parametric pendulum is employed to obtain numerical predictions,while measured data of vibration tests during the passage of a Thalys high-speed train are considered as input forcing.Since a sustained rotation is the most energetic motion of a pendulum,the possibility of achieving such state is evaluated,taking into account the influence of initial conditions,damping and other factors.Numerical simulations show that rotating pendulum harvesters with sufficiently low viscous damping could be able to generate a usable average power on the order of 5–6 W per unit.Considering a modular arrangement of devices,such energy is enough to feed variety of rail-side equipment,as wireless sensors or warning light systems.However,a suitable choice of initial conditions could be a difficult task,leading to the need of a control action.

Systematization of features and requirements for geological survey of railroad subgrades functioning in cold regions

The operation of a railway track in cold regions results in the premature deformation of subgrade soils caused by significant temperature fluctuations and ecological imbalance.Identification and calculation of the thawing degree of permafrost soils,frost heaving of clays,and groundwater flooding require careful engineering and geological surveying.The paper describes the unique,long-standing experience of the university scientists connected with maintaining the Russian EastSiberian and Trans-Baikal Railways'facilities.Specific features of and requirements for the surveying,depending on the geological and climatic conditions,are identified.

Life Cycle Assessment of Creosote-Treated Wooden Railroad Crossties in the US with Comparisons to Concrete and Plastic Composite Railroad Crossties

Creosote-treated wooden railroad crossties have been used for more than a century to support steel rails and to transfer load from the rails to the underlying ballast while keeping the rails at the correct gauge. As transportation engineers look for improved service life and environmental performance in railway systems, alternatives to the creosote-treated wooden crosstie are being considered. This paper compares the cradle-to-grave environmental life cycle assessment (LCA) results of creosote-treated wooden railroad crossties with the primary alternative products: concrete and plastic composite (P/C) crossties. This LCA includes a life cycle inventory (LCI) to catalogue the input and output data from crosstie manufacture, service life, and disposition, and a life cycle impact assessment (LCIA) to evaluate greenhouse gas (GHG) emissions, fossil fuel and water use, and emissions with the potential to cause acidification, smog, ecotoxicity, and eutrophication. Comparisons of the products are made at a functional unit of 1.61 kilometers (1.0 mile) of rail-road track per year. This LCA finds that the manufacture, use, and disposition of creosote-treated wooden railroad crossties offers lower fossil fuel and water use and lesser environmental impacts than competing products manufactured of concrete and P/C.

Suggestion of Maintenance Criteria for Electric Railroad Facilities Based on Fuzzy TOPSIS

This paper is on the suggestion of maintenance items for electric railway facility systems.With the recent increase in the use of electric locomotives,the utilization and importance of railroad electrical facility systems are also increasing,but the railroad electrical facility system in Korea is rapidly aging.To solve this problem,various methodologies are applied to ensure operational reliability and stability for railroad electrical facility systems,but there is a lack of detailed evaluation criteria for railroad electrical facility system maintenance.Also,maintenance items must be selected in a scientific and systematic method.Therefore,railroad electrical facility systems are selected for study.Design StructureMatrix(DSM)is utilized to establish considerations tailored to the maintenance characteristics,and the Fuzzy-TOPSIS methodology is utilized for determining the maintenance detail evaluation item baseline weights,a multi-criteria decision-making problem.Studies show that degradation,insulation items have the highest weight of 14.63%,and capacity items have the lowest weight of 5.34%.The results of this may be contributed to the underlying research in carrying out maintenance activities to ensure the reliability and safety of railroad electrical facility systems.

Railroad capacity tools and methodologies in the U.S. and Europe

A growing demand for passenger and freight transportation, combined with limited capital to expand the United States （U.S.） rail infrastructure, is creating pressure for a more efficient use of the current line capacity. This is further exacerbated by the fact that most passenger rail services operate on corridors that are shared with freight traffic. A capacity analysis is one alternative to address the situation and there are various approaches, tools, and methodologies available for application. As the U.S. continues to develop higher speed passenger services with similar characteristics to those in European shared-use lines, understanding the common methods and tools used on both continents grows in relevance. There has not as yet been a detailed investigation as to how each continent approaches capacity analysis, and whether any benefits could be gained from cross-pollination. This paper utilizes more than 50 past capacity studies from the U.S. and Europe to describe the different railroad capacity defini- tions and approaches, and then categorizes them, based on each approach. The capacity methods are commonly di- vided into analytical and simulation methods, but this paper also introduces a third, ＂combined simulation- analytical＂ category. The paper concludes that Europeanrail studies are more unified in terms of capacity, concepts, and techniques, while the U.S. studies represent a greater variation in methods, tools, and objectives. The majority of studies on both continents use either simulation or a combined simulation-analytical approach. However, due to the significant differences between operating philosophy and network characteristics of these two rail systems, European studies tend to use timetable-based simulation tools as opposed to the non-timetable-based tools commonly used in the U.S. rail networks. It was also found that validation of studies against actual operations was not typically completed or was limited to comparisons with a base model.

THE ROLE OF RAILROAD IN THE DEVELOPMENT OF THE AMERICAN WEST—Railroad,Migration and Urban Growth

This paper explores the role of geographical expansion of railroads,one of the most important Fransporta-tion vehicles,in the history of American west development,analyses its implication on the unprecedented mi gration move-ment and the resulted urbanization i n the west and concludes with the fact that the appropriate interference b y the governm-net,especially in the early period,is vital to regional development pra ctice,because of market failure at t he initial stage,infrastructure constructio n conducted by the government always plays as the first impetus to any regional develop-ment process.Only through this brid ge,can some physical factors,such a s population,be attracted to feed th e back-ward area.As a result,cities grow fa st and the region develops well.The e xperience can be shared by all countr ies.Be-sides reviewing the history of west development in America,focusing on t he relationship between railroads e xpansion and urban growth,which was realized thr ough population migration.Acomparison on the particular pattern of regional develop-ment between U.S and China is made as well at the end.It is noted that despite of the common first impetus,govern-ment subsidies and the common final r esult,urbanization,the path for th e America is bottom-up,whereas that for China is top down,that is to say,developme nt should originate from big cities,then to towns,and finally radiate in to rural ar-eas.

Thermal state of ice-rich soils on the Tommot-Yakutsk Railroad right-of-way

This paper summarizes the results of investigations carried out in the northern section of the Tommot-Yakutsk Railroad in eastern Siberia, underlain by ice-rich permafrost. The ongoing permafrost and geotechnical research program in support of railroad construction includes assessment of the ground thermal state on the right-of-way and adjacent areas based on long-term field observations using the method of terrain thermal physics. These studies focus on the upper permafrost within the depth of annual temperature variation. In undisturbed areas, inter-annual variability of the ground thermal state shows little response to recent climatic variations. However, forest clearing and surface disturbance during right-of-way construction cause an increase in permafrost temperature, deepening of the active layer, thaw settlement, and water accumulation along the embankment. The active layer is thickest along the sun-exposed left berm and is thinnest along the more shaded right berm. Measures to prevent thaw-related embankment problems are recommended.

Integrated geophysical surveys on railroads in permafrost areas

The zones of thawed ground in the permafrost area are most dangerous from engineer-geologist effect point of view. Detection of such zones, as making forecast of their movement is the main task of engineer-geologist survey been held in railway industry. This paper presents general issues concerning railway construction and operation in permafrost areas. Comprehensive geophysical methods to monitor the development of thawed soils axe considered in detail. The main physical parameters which help define permafrost and thawed soil patches are described. Author of current paper pointed out main factors, allowing predicting potential areas of development of thawed grounds. They offered set non-destructive methods： GPR investigations, seismic survey and elec- tric exploration. Whole sets of geophysical data： electric resistivity, velocity of S-wave and P-wave （and their correlation）, allow us with high confidence specify characteristics and state of soil either under the line of road, or near it. At the same time the meth- od allows to predict direction of further development of thawed ground area.

2018 Railroad Tie Survey

This article reports results of a survey of railroad tie management conducted by the Association of American Railroads (AAR) reflecting 2017 practices. Similar surveys were previously conducted for 2013 and 2008 practices. North American railroads purchase approximately 23 million new wood crossties annually. Most ties are used to replace worn ties. Through this survey, the AAR seeks to provide clarity to its member railroads, the regulators, and other interested parties, regarding how the railroads’ tie purchase preferences and used tie management choices have been changing in response to changing technologies and regulations. Technology changes include use of borate preservatives to dual-treat wood ties to provide longer service life in high decay environments, non-wood ties made of concrete or plastic, and energy conversion methods for used ties such as gasification and torrefaction. Passage of the EPA Non-Hazardous Secondary Materials (NHSM) rule in 2011, including updates in 2013, 2016, and 2018, is reducing the potential for recycling used ties as fuel. However, the EPA is also promoting use of biological materials, such as wood, to produce energy without increasing carbon dioxide (CO2) levels in the atmosphere, thus reducing human caused climate change. Purchase and tie management trends are indicated by the survey results. Approximately 95% of all ties purchased are preservative-treated wood. Due to demonstrated longer service life in high decay zones for wood ties that are dual treated with borate and either creosote or copper naphthenate, the fraction of concrete and plastic tie purchases has decreased while the faction of dual treated wood tie purchases has increased. Recycling used ties for energy remains the most common practice, at 66% of ties, but has declined from 81% in 2013. Reuse of ties for other treated wood uses, such as landscape and agricultural type purposes, remains common at approximately 18%. Landfill disposal remains uncommon, but seems to be increasing at 6% of removed ties. The shift away from recycling for energy is thought to result from the both impact of the EPA NHSM rule and the low cost of natural gas. The smaller market tie users, mainly the short line railroads in contrast to the Class 1 railroads, manage far fewer ties per company, but purchase and manage approximately 31% of all ties. The short lines recycle to landscape and agricultural uses at about half the rate of the Class 1s and dispose in landfills at a much higher rate of 76% versus 1.2% for the Class 1s. This difference is thought to result from the economics and availability of local versus distant management options.

Clinical Analysis of GPT Alteration of Constructors for Qinghai-Tibetan Railroad at Different Altitude Areas

Objective: To observe the effect of hypoxia on the liver function of constructors at high altitude. Method: Select 221 constructors aged 23～42 as subjects, who had worked for 3～6 months at 4500 m. Collect venous blood from fasting subjects and determine GPT by new Lai’s Method from “The Nationwide Clinical Inspection Operating Rules". Results: The study indicated that the GPT of 45 subjects among Group 1 were abnormal, with the proportion of 20.3%. The peak of GPT appeared when subjects exposed to high altitude of 4500m for 1 month, and the mean value was 83.76±9.23.The GPT of workers were higher than that of administers at different altitude (p<0.05). And the GPT of subjects at 4500 m were higher than those at 3500 m (p<0.05). We can find a degrading tendency with the increasing of working time (p<0.05). There was significantly statistic difference between two groups. Conclusions: The study confirmed that hypoxia could cause the change of liver function mildly and moderately. And there was a positive correlation between the degree of hypoxia and liver function. But, the change began to become a decreasing trend when people went on working longer. We also found that the change of liver structure and function at high altitude correlated with several factors else, including labor, individual difference, methods and sensitivity to the test. However, the explanation of its key mechanism deserves further investigation.

Impact of permafrost change on the Qinghai-Tibet Railroad engineering

Permafrost along the Qinghai-Tibet Railroad produces the great change under the influence of climate change, such as the decreasing of permafrost table, the rising of permafrost temperatures, etc. Climate effect on permafrost is the long-term process. Engineering action makes rapidly permafrost the large extent change. On the basis of analyzing the permafrost change under the climate change and engineering action, the thermal regime and spatial distribution of permafrost are predicted for air temperature rising 1℃ and 2℃ after 50 years in this paper. The results show that climate change results in the larger change for the thermal regime and spatial distribution of permafrost. Permafrost change will produce the great effect on the Qinghai-Tibet Railroad engineering, not only resulting in the decreasing of permafrost table beneath the roadbed, but also resulting in thawing settlement due to the thawing of ground ice near permafrost table. The idea of cooling roadbed and active protecting permafrost for the Qinghai-Tibet Railroad engineering could adjust and control the permafrost thermal state, some better methods are provided to ensure the engineering stability in the areas of warm permafrost and high ice content.

Characterization and impact analysis of freezing and expansion disease of roadbed in seasonal freezing zone: A case of heavy railroads

The freezing and expansion diseases of railroad roadbeds are prevalent in areas that experience seasonal freezing.This study aims to investigate the features of the freezing and expansion mechanism of seasonal frozen railroad roadbeds and the effects of the freezing and expansion diseases on the roadbeds.This article presents a study of the Shuo-Huang Heavy Duty Railway.Initially,on-site monitoring tests were conducted to analyze the roadbed temperature,water content and deformations due to freezing.Through these tests,the pattern of development of the roadbed freezing and swelling was understood,and the effect of this on the vibration response of the roadbed was investigated.Subsequently,load-free freezing tests were performed to investigate the freezing and expansion features of the roadbed.Through on-site monitoring,it has been determined that the seasonal freezing layer is approximately 0.5 m deep.The depth of the frozen expansion on both sides of the road shows clear differences.The frozen and expansion disease significantly amplifies the vibration acceleration of the roadbed,with a tendency towards low-frequency and high-amplitude vibrations.Through indoor testing,we compared the deformation of frozen specimens and their final freeze and expansion rates at different cold-end temperatures and various initial moisture content levels.We find that the initial moisture content has a greater impact on specimen freezing and expansion.The findings in this paper can be used as a reference for researching and addressing roadbed freezing and expansion problems.

高原铁路某特长隧道独头掘进通风技术分析

文章面向高原铁路特长隧道,开展通风技术研究,提出一种基于避车洞通风技术、人行通道通风技术的蓄风房通风策略。基于高原铁路特长隧道通风案例,研究了蓄风房技术。文中研究成果供我国高原铁路特长隧道建设单位、运营单位加以参考、借鉴,以保证特长隧道通风性能,满足相关制度、规范对高原铁路特长隧道的环境要求,并实现铁路通风的节能效果。

A 'GREEN' RAILROAD?

Environmental issues may dictate the success of the Qinghai-Tibet Railway "The environmental requirements in the construction of the Qinghai-Tibet Railway have basically been fulfilled, except for the environmental restoration work in a handful of sections,"

基于多通道数据的高铁司机警觉评估实验设计

高铁司机警觉与行车安全密切相关。为实现司机警觉状态评估,该研究设计了一种基于多通道数据的高铁司机警觉评估实验方案。依托高铁驾驶模拟器,以连续驾驶的方式诱发高铁司机警觉衰退,实验过程中同步采集其脑电、心电、眼动以及简单反应时间和疲劳程度主观量表。基于神经网络、支持向量机等机器学习技术构建司机警觉评估模型技术方案。以司机神经、生理等融合特征为输入,以司机疲劳状态为输出,构建司机警觉评估模型,对提出的实验方案进行探讨,验证提出的实验方案的合理性与可应用性。

小半径隧道盾构施工对铁路桥梁的影响

随着城市轨道交通线网的完善,单一的直线型隧道已不能满足需求,而新建隧道也不可避免地近接建构筑物,势必危及建构筑物,甚至引发严重的安全问题。基于郑州地区某工程,运用有限元软件Midas GTS NX进行数值模拟,研究小半径隧道盾构施工期间隔离桩防护措施的作用效果,并结合监测数据验证数值计算的准确性。研究结果表明:1)在无隔离桩防护措施下,小半径盾构隧道施工会引起地表横向沉降变形,危及铁路线路运营安全;2)在隔离桩防护措施下,小半径盾构隧道施工对铁路桥梁的影响在可控范围内,能有效降低盾构隧道施工引起的铁路桥梁变形及其附加内力,有利于铁路线路的运营安全;3)监测数据与数值计算的对比表明,隔离桩防护措施对于保障铁路线路的运营安全是有效的。本文研究结果可为盾构隧道安全穿越铁路桥梁施工提供重要的工程实用价值。

重大铁路工程施工对沿线生态环境的影响

重大铁路工程施工途经多个地貌单元,地形地貌复杂,生态环境脆弱。基于地理探测器模型,利用遥感数据,选取客观权重赋权法(CRITIC)整合4个指标绿度(NDVI)、湿度(WET)、干度(NDBSI)、热度(LST)构建遥感生态指数。以投入运营的铁路工程为例,剖析其沿线生态环境变化效应及驱动因素。通过客观分析铁路工程沿线生态环境时空变化特征,旨在实现铁路与区域环境的可持续发展。研究为重大铁路工程建设生态环境评价提供方法支撑,为铁路沿线生态修复与保护政策的制定奠定基础。

某型号轨道牵引车悬挂系统隔振性能优化

为提高动力牵引车行驶的稳定性,采用四端参数法推导了车辆系统隔振传递率计算公式,并以隔振传递率峰值最小为目标,对悬挂系统阻尼系数、弹簧刚度等结构参数进行了优化分析。另外,基于Simpack建立了该车的多体动力学模型,以列车垂向振动响应均方根值的最小值为优化目标,计算得到车辆系统的一系悬挂参数最优值。结果表明:阻尼值理论计算和仿真结果之间最优值误差几乎为零,弹簧刚度误差为3.4%,验证了基于四端参数法对该车一系悬挂参数优化理论模型的准确性。此外,当扰频比在0.5以内时,阻尼系数对车辆垂向振动响应的贡献较大;随着一系悬挂系统中减振器阻尼值的增大,车辆系统隔振传递率先减少后增大,弹簧刚度对其影响与之类似。