Introduction. The article examines the key scientific and technical problems arising at design and construction of the KS-400 overhead contact line for Russian high-speed railways and presents their solutions based on the results of numerical simulations and stage-by-stage tests. At high train speed, electric current loads increase and dynamic interaction between pantographs and catenary becomes more complex. To provide a required quality of current collection, an extensive study of the parameters affecting mechanical, electrical and thermal processes in the pantograph-catenary interaction system must be carried out. The aim of the presented study is to ensure reliable operation of the overhead contact line assemblies and components in the wide range of operational conditions.

Materials and methods. Numerical simulation methods have been employed in the design of the KS-400 overhead contact line. The contact line is simulated with a detailed finite element model and the pantographs are modeled using multibody dynamics approach. Numerical models employ a three-dimensional nonlinear formulation. Dynamic problems are directly solved in the time domain by numerical integration of the system of finite element equations over time. Contact interaction between catenary and pantographs is modeled using the penalty method. The compliance of the overhead contact line parameters and the individual hardware components with regulatory requirements is confirmed by mechanical, electrical, thermal and other types of tests.

Results. The KS-400 overhead contact line assemblies and components have been designed based on the results of numerical simulation. It has been shown that the obtained indicators of current collection quality are within the allowable margins. The main technical solutions for the KS-400 overhead contact line and the key stages of its design and construction are presented in the article.

Discussion and conclusion. To date, large amount of design, research and development work on implementing the KS-400 overhead contact line for Russian high-speed railways have been carried out. The prototype hardware components have been manufactured. A pilot overhead contact line section has been built at the Experimental Loop of the Railway Research Institute. The tests due are currently underway. In order to confirm operational compatibility of the KS-400 with other railway subsystems and to check the quality of current collection at high train speed, further field tests are scheduled at the Kryukovo – Novaya Tver experimental site which is a part of the designed Moscow – St. Petersburg high-speed railway.

Introduction. The active use of geosynthetic materials in the modernisation of railway track in order to enhance its mechanical stability leads to a significant increase in the electrical ballast layer resistance. This presents challenge for electri- fied AC railways, as it disrupts the normal flow of reverse traction currents and leads to dangerous potential differences between the rail and the ground. The aim of the study is to develop and verify a physical-mathematical model for the as- sessment of potential difference between the rail and the ground on electrified AC railways sections for a quantitative assessment of rail potential and analysis of the effect of the ballast prism structure on its distribution.

Materials and methods. In order to solve the problem, the authors developed a refined physical-mathematical model based on the finite element method, which allows to consider the spatial heterogeneity of the electrical parameters of the pipe. The model integrates the resistance of various structural elements of the track: rails, sleepers, ballast and roadbed. Field experiments were conducted on the Experimental Loop of the Railway Research Institute to validate the model.

Results. Experimental studies confirmed the adequacy of the developed model. The calculation results demonstrated a high degree of consistency with the field measurements data of the potential distribution along the way. As a result of the work carried out, a tool has been created for solving applied problems related to determining the potential difference between the rail and the ground.

Discussion and conclusion. Comparison of the experimental and calculated data of the refined physical-mathematical model shows that the developed model is presented as an effective tool for predicting potentially dangerous sections at the ballastless track superstructure design.

Introduction. The development of high-speed main line with the speed up to 400 km/h is strictly connected with the major problem of insufficient normative technical documentation which regulates methodology of railway design calculation, including stability from extreme temperature and strength under its combined action with rolling stock. The aim of the article is to develop methodology for assessing the stress-strain state of a continuous welded rail track on a ballastless track based on strength and stability, as well as to assess temperature release risks and loss of rail string strength.

Materials and methods. In order to calculate continuous welded rail track for stability the authors employed method which involves accounting for rail string initial unstressed unevenness of the most unfavorable shape. Finite element method was used to estimate continuous welded rail track strength.

Results. The calculations show that the permissible temperature increase of rail string in comparison with fixing temperature under the terms of stability may be equivalent to 111 °С, and permissible temperature decrease of the rail string is 98 °С, which is comparable to the traditional track design on a ballast.

Discussion and conclusion. Ballastless design of the superstructure, required by documentation, has greater stability capacity in comparison with traditional design on a ballast. Technical solutions of ballastless track design of superstructure on pointless sections placed on roadbed nearly eliminate risks of mechanical safety violation both in terms of strength and stability. As a part of experimental operation of high-speed railway line on Sablino – Tosno space interval and Alabushevo – Novaya Tver section, analytically calculated temperature increase value of rail string in terms of fixing temperature under the terms of stability and temperature decrease value of rail string in comparison with the fixing temperature under the terms of strength using finite element modelling should be proven experimentally.

Introduction. The Eastern Polygon, which covers Trans-Baikal and Far Eastern Russian railways, is characterised by increased freight traffic with an expected growth in the near future. The operation of traction power supply devices in certain areas is associated with a high current load, including reverse traction network. Special measures are required to secure the network and keep it operational.

Materials and methods. Rosengartovka – Boytsovo – Bikin section of the Far Eastern Railway was chosen as the research object to assess the impact of joint operation of reverse traction AC network devices and railway automation and telemechanics. The section is located on the main electrified course of the Trans-Siberian railway with an AC traction with 25 kV voltage. Comparative analysis of the effectiveness of the most significant measures in terms of impact on improving the security of railway automation and telemechanics devices was carried out when working with a 25 kV reverse traction AC network.

Results. The operation parameters of reverse traction AC network with 25 kV voltage in the study area were determined. The factors of mutual influence on the performance parameters in conditions of real movement of heavy-load trains arising in the operation of the reverse traction network and the degree of their influence on the performance of railway automation and telemechanics devices are estimated.

Discussion and conclusion. According to the results of the research conducted on the section of the Far Eastern Railway, evidence is provided on the possibility of increasing the critical voltage of switching devices up to 2500 V. Technical measures were developed and classified to minimise the impact of 25 kV reverse traction network modes on the operational performance of railway automation and telemechanics devices, indicating the degree of their impact and evaluating the achieved effect.

Introduction. Collector traction motors of sequential excitation are widely used on DC and AC electric locomotives, which disadvantage is their increased tendency to slip. It is necessary to find a modern solution to the urgent task of improving coupling properties of electric locomotives. In this regard, the processes of disrupting and restoring the coupling of wheel pairs of an alternating current electric locomotive with controlled excitation converters of collector traction motors should be considered, providing smooth transitions to sequential and independent excitation characteristics, as well as the pos- sibility of smooth control of excitation currents and traction forces in these modes. The objective of the paper is to develop proposals to improve the coupling properties of electric locomotives.

Materials and methods. The authors propose a methodology for studying the clutch failure of an electric locomotive wheel pair. The processes of interaction of wheel pairs and rails when hitting an oil stain are considered, and the values of traction forces, adhesion forces, and the speed of wheel pair slippage are determined. The study of these processes was carried out using a mathematical model developed in the Matlab/Simulink software package.

Results. The results of processes study in case of clutch failure under one wheel of a wheel pair, as well as in case of clutch failure under both wheels of a wheel pair, showed that the clutch force of the first wheel pair becomes significantly lower than the thrust force of the engine rather than in case of clutch failure under one wheel. This causes a considerable increase in the relative sliding speed of the wheel from 6.9 % when the clutch is broken under one wheel to 9.5 % when the clutch is broken under both wheels. At the same time, the speed of the wheel rotation increases.

Discussion and conclusion. The results obtained in this article may be used for the development of traction force control systems at the adhesion limit and wheel pair slip control systems for AC freight electric locomotives with controlled exci- tation converters for commutator traction motors.

Introduction. The need to develop and improve the transport and logistics infrastructure of railway, automobile, river, sea, and air transport modes in the current conditions of macroeconomic transformation and limited investment resources requires the identification of evidence-based proposals for the modernisation of existing facilities of the regional terminal and logistics infrastructure, as well as the implementation of additional measures to develop the main infrastructure of the junction. The measures under development should consider the projected volumes of transport and logistics services based on analysis of the dynamics of freight flows, their structure and correspondence directions and ensure an increase in the level of economic connectivity of the Russian Federation. The purpose of this study is to develop a methodological approach to determining the need for the development of regional transport and logistics infrastructure facilities with the identification of limiting “bottlenecks” in the maintenance of relevant freight flows.

Materials and methods. The authors employed the following scientific and methodological approaches, including statistical and econometric methods for analysing the cargo base, balance methods for studying transport and economic relations in the country, methods of planning and traffic flow management, methods of modeling and optimising transport and logistics infrastructure, methods of system analysis of transport and technological systems.

Results. A methodological approach to the development of the existing regional transport and logistics infrastructure has been developed, including methodological principles for assessing the cargo base of the region according to the main cargo nomenclatures using the transport and economic balance, economic and mathematical model of transport and lo- gistics services for freight flows, which ensures the distribution of selected cargo nomenclatures based on transport and economic links across the operated facilities of the transport and logistics infrastructure of the considered region, characterised by specified values of technological parameters, as well as the identification of limiting “bottlenecks” in the main- tenance of relevant freight flows.

Discussion and conclusion. The use of the proposed methodological principles and developed economic and mathematical model would enable to obtain complete and objective information on the sufficiency of the development of the regional transport and logistics infrastructure, determine the limiting (scarce) or excess (reserve) processing capacities of cargo fronts according to the selected nomenclature cargo groups. This gives an opportunity to proceed to the deve- lopment of a gradual range of measures to remodel the existing transport and logistics complex of the region and substan- tiate technological capacities.