The safety of freight trains motion that have empty cars in their composition is in many cases determined by the stability of the motion of these cars. The problem is that the intense horizontal non-stationary-periodic oscillations arise due to the conicity of the wheel treads with the weak connection of the wheelsets with the side frames of the three-piece bogie of the freight car at a certain (critical) speed of motion. These oscillations begin to threaten the safety of train motion when the car's speed exceeds its critical value by 20-25 km/h. Numerically, the conicity is determined by the angle between the generatrix of the conical surface and the axis of the cone. The results of experimental studies and theoretical calculations show that within creasing conicity of the wheel treads of freight cars, the value of the critical speed decreases substantially. The article describes a method of an estimation of an equivalent conicity of wheel treads of cars with the worn out surface of rolling. The method is based on calculating the coefficients of a polynomial over even grades of the lateral oscillations amplitude of a single freely moving wheelset in the tangent segment of the track. Coefficients of the polynomial contain factors determined by the function of the difference in the radii of the worn wheel in sections equidistant from the vertical axis passing through the middle position of the point of contact between the wheel and the rail on the wheel tread. This method will help to further clarify the timing of car's wheel-turning on the condition of ensuring the safety of empty freight trains, taking into account the actual condition of the rolling surfaces of the wheel treads.

The article is analyzing the possibility of using an additional parameter for the calculation of the formation of one-group trains, allowing to take into account the costs associated with the motion of rolling stock. A study was carried out at a number of railway sections of the Belarusian Railways aimed at identifying factors that affect the sectional speed of freight trains. The analysis of the obtained results made it possible to conclude that there is a relationship between the train category and its sectional speed. Depending on the traffic intensity and capacity of the site, the difference between the sectional speeds of transit and sectional trains in the investigated areas was from 2 to 18 %. In the development of the train formation plan, it is proposed to apply a new additional parameter for saving costs for cars and locomotives in transit trains Rn . Authors propose formulas for calculating the value of this parameter. The influence of some factors was analyzed including the train composition and mass, the length of the section, the power of the car stream on cost savings when using the proposed parameter in the calculations. The application of the parameter of cost savings in the cars and locomotives in transit trains makes it possible to justify the allocation of separate streams of car traffic for independent purposes, which would be considered economically unprofitable when developing a train formation plan based on calculations performed by traditional methods.

The monitoring of railway rails damage on the railway network of the JSC “Russian Railways” as well as operational and polygon tests are conducted with the purpose of assessing the impact of operating conditions on the intensity of rails damage, obtaining initial data for forecasting rails failures. The increased intensity of rails wear on sites with a complex plan and profile leads to the fact that with a continuous change from the track, rails which have an underutilized service life of more than 20 % are retrieved. Polygon tests on the Test Loop of the JSC “VNIIZhT” near the Scherbinka station can provide the repeatability and reliability of the results, comparative tests are carried out under identical conditions and their duration is several times less than when tested at experimental sites under operational conditions. The results of the polygon tests of new differentially heat-strengthened rails did not reveal any advantages in the wear resistance of special purposed rails (laid in the recommended radius of the curve for its application) when comparing the rails of domestic manufacturers. Metal shelling out on the rolling surface of rails is the main reason for the removal of rails from test batches. The origin and development of defects of this kind is due to both violations of the technology of manufacturing rails, and because of violations of the current maintenance of the track. The metal stock in the area of the rail head of R65 type due to the increase in its dimensions positively affects the extension of the lifetime of the rails, reducing the cost of the life cycle and the rail itself, and the design of the track as a whole. When carrying out a separate study in order to obtain results characterizing the stability of high-quality rails to contact fatigue damage, it is advisable to optimize the conditions of the polygon tests, bringing them closer to operational ones. When forming the test results, it is necessary to expand the list of criteria for assessing the wear resistance of rails, supplementing it with the size of the wear area at the time of a certain operating time of the tonnage, with the introduction of this criterion into the appropriate methods for the polygon (operational) tests.

Analysis of operational data for defective and highly defective rails showed that up to 25 % is the contact-fatigue defects. In connection with the development of heavy haul traffic on the Russian railways, it is relevant to determine the influence of cars with increased axial loads of 25 and 27 tf on the contact fatigue life of rails. The solution of this problem is set forth in this article. The Brown-Miller model of multi-axial fatigue was used in the calculation. This model is integrated into the Fatigue software system, which is tied to the Marc calculation system through Pat-ran. Since under operating conditions the wheel moves (rolls) along the rail on meandering trajectory, in computer modeling weight coefficients were taken into account that characterize the percentage of wheels in the cross-sectional areas of the rail. Calculations of contact fatigue life took into account the variability of vertical loads from the impact on the track of trains formed from innovative open cars with axial loads of 23.5, 25 and 27 tf under operating conditions, loaded with real loading blocks. According to the analysis of calculated data with an increase in axial loads from 23.5 to 25 tf, it is necessary to expect a decrease in the service life of rails in contact fatigue resistance by 19 %, with a further increase in axle loads of up to 27 tf per 32 %. Considering that the share of freight cars with axial loads of 25 tf does not exceed 15...20 %, then on the routes of its use the service life of rails should be expected to decrease by 3...4 %. The method proposed by the authors for predicting the contact fatigue life of rails with increasing axial loads is advisable to improve in part of the experimental determination of the fatigue and strength characteristics of rail steel from the degree of hardening of the rolling surface, its probabilistic properties and the use of the integral distribution law for vertical forces, taking into account the structure of the freight traffic passing through the section. The work was carried out according to the RFBR project 17-20 01088.

With the introduction of polygon site technologies, the extension of locomotive circulation areas has increased the complexity of solving the problems of regulating the fleet of locomotives. Determination of the required rational size of the irreducible reserve of locomotives at the stations of its turnover is currently carried out in order to extinguish the influence on the export of the inaccuracies in the planning and inadequate depth of the forecast of the car traffic flows. Substantially this determination is made on the basis of expert assessments and does not have sufficient methodological justification. In order to exclude the loss of the traffic threads in the schedule, it is necessary to create a rational irreducible reserve of locomotives at the stations of its turnover. To solve this problem, a mathematical model of train operation has been developed on locomotive circulation areas, taking into account the daily fluctuations of train traffic, possible deviations in predicting composition formation and other factors. Performing mass calculations for various conditions will allow determining the rational size of the irreducible reserve of locomotives at the stations of its turnover and eliminate the losses associated with the cancellation of the schedule threads due to the lack of provision of finished trains by locomotives. Extensive full-scaled tests were made to determine the difference between actual and planned train traffic, which allowed determining regularities in the formation of planned values of train traffic for use in the simulation model. An algorithm for constructing a simulation model has been developed that provides for the amount of a irreducible reserve of locomotives for different conditions: changing values of the average daily train traffic in the even and odd directions of traffic, traffic incompatibility, the degree of uneven daily traffic, errors in planning (planning quality), etc. The software of the simulation model was developed and its debugging was made to perform mass calculations. The study of the problem of determining the rational size of the irreducible reserve of locomotives at the stations of its turnover was carried out with the support of the Russian Railways and the Russian Foundation for Basic Research. Project No. 17-20-01136.

The article is substantiated the necessity of intro-and dynamics of change are proposed to be implemented within ducing the mechanism of predictable maintenance of railway trans-the framework of a specially created decision support system. It port infrastructure into the practice of the transportation process. was also proposed to use the mathematical apparatus of queuing The functions of object monitoring, diagnostics of their condition theory to implement the tasks of analyzing and synthesizing the structure and functions of the system for organizing maintenance of transport infrastructure facilities. Within the framework of this tool, a mathematical model for the synthesis of maintenance systems for railway infrastructure facilities was constructed and analyzed, and a network of queuing systems describing monitoring, diagnostics and maintenance of these facilities was considered. The analysis technique of the infrastructure objects includes the procedure for structuring the railway transport object in the form of a combination of queuing systems and queuing networks, analysis of their parameters, analysis and optimization of information flows in queuing networks. The features of the application of the developed model for the solution of three practical problems are analyzed: technical and commercial inspection of trains at the sorting station reception, identification and correction of wheelset defects on thermal anomalies, development of a system for diagnosing the negative dynamics of freight cars. A model is described that allows calculating the main parameters (service intensity, service time and location in network) for a network that includes the source of applications (the transportation process), the diagnostic subsystems (as part of the decision support system - DSS) and the maintenance depoes.

The analysis of failure of unhardened and heat-strengthened R65 rails under operating conditions in the tangent sections of the track is presented taking into account the influence of the most important operational factor - the average static axial loads of the rolling stock. Non-reinforced R65 rails in the jointed track on the 12.5 m long wooden sub-rail base were considered based on the results of their single replacement in the entire range of their failures. The work of rails under operating conditions is estimated at average static axial loads of rolling stock as 7.5, 9.5, 16.5 and 19.5 tf (73.55, 93.16, 161.82 and 191.21 kN) at all stages of the tonnage at each load. The influence of the average static axial loads of the rolling stock on rail failure in specific operating conditions has been revealed. The features of the change in the intensity of rail failure are considered at all stages of their operation, both for the specified and for the average network level of the static load. The obtained statistical data on the effect of axial loads of rolling stock on the operation of rails can be used in the practice of track maintenance. In conditions of increasing axial loads up to 25, 27 tf, it is necessary to use rails of the appropriate quality; also it is expedient to create new rails for such operating conditions. It is necessary to perform an evaluation of the real operational qualities of the rails in order to use the rolling stock with the increased axial loads (25, 27 tf) in the transportation process in the most efficient way. In the long term, the results of such studies will be aimed at improving the operation of the systems for running track and railway car complexes.

The article considers the possibility of using a modular concept for placing and fixing various kinds of goods with the help of an innovative method of using fitting stops for transportation by rail fitting platforms. It was noted that an increase in the efficiency of rail transport is facilitated by the expansion of the nomenclature of goods transported on a specialized rolling stock. Conditions for the use of fittings for the transportation of long rails have been analyzed, and also the shortcomings of the existing technology of locating and fastening goods have been revealed. A method is suggested, the application of which will allow expanding the range of goods transported on one of the types of rolling stock - fitting platforms. The conducted researches confirm the technological effectiveness and economic attractiveness of the modular concept of the use of fitting platforms. It is noted that giving the specialized rolling stock the properties of universality will help expand the scope of use of a fleet of cars of this type. Further implementation of the necessary technical and economic calculations and tests is planned for the practical implementation of the developed concept of the transportation of long goods on fitting platforms.

When forecasting the technical state of the parts and units of railway rolling stock in operation, an important task is to determine the shape of the discontinuity in ultrasonic non-destructive testing in order to predict its behavior in further operation (this is especially important if the discontinuity in the results of such control is acceptable). Author proposed a solution for the improvement of the two-frequency defectometry method. A mathematical apparatus was developed and a method for determining the coefficient of the discontinuity shape was elaborate on its basis. The method makes it possible to determine the shape of both a point and an extended discontinuity. The software product NDTRT-07.03.01.18 was developed to automate calculations in determining the shape of discontinuity by a two-frequency method. The article gives a description of the experimental studies carried out to evaluate the reliability of the proposed method. This method can be used in determining the shape of the discontinuity in the details of the rolling stock, in which the defect can have a different shape, for example: cast wheel centers; various shaped castings used in the manufacture of rolling stock units (brackets for locomotive bogies, cast sidewalls for cars), as well as in parts manufactured by the method of plastic deformation, including wheel treads, axles, all-rolled wheels, rolled wheel centers, etc. In these details discontinuities are predominantly planar in nature, but voluminous discontinuities are also encountered - non-deformable nonmetallic inclusions, therefore the developed method can be applied to such objects of rolling stock railways.