The aim of the presented paper is to show the results of shape optimization of railway polynomial transition curves (TCs) of 5th, 7th, and 9th degrees through the use of the full vehicle model and new criteria of assessement concerning the jerk value. The search for the proper shape of TCs means that in this work, the evaluation of TC properties is based on select quantities and the generation of such a shape through the use of mathematically understood optimization methods. The studies presented have got a character of the numerical tests. For this work, advanced vehicle models describing dynamical track-vehicle and vehicle-passenger interactions as well as optimization methods were exploited. In the software vehicle model of a 2-axle freight car, the track discrete model, non-linear descriptions of wheel-rail contact are applied. This part of the software, the vehicle simulation software, is combined with a library optimization procedure into the final computer program.
Due to different reasons a significant modal shift from railway to road transport took place over last decades. The basic reasons are pointed in the paper introduction together with contradicting transport policy taking into account environmental and economical challenges. Political vision to stimulate modal shift from road and air to railway cannot become true without achieving railway technical and operational interoperability. Paper describes wide range of technical barriers between individual intraoperable railway systems in civil engineering structures, traction power supply, control command and signalling and the ways, which are being applied to ensure stepwise converging of the technical solutions taking into account safety and technical compatibility, as well as other essential requirements, namely: reliability, accessibility, health and environment.
The acoustic climate assessment needed for the selection of solutions (technical, legal and organisational), which will help to minimise the acoustic hazards in the analysed areas, is realised on the basis of acoustic maps. The reference computational algorithms, assigned to them, require very thorough preparation of input data for the considered noise source model representing - in the best possible way - the acoustic climate. These input data are burdened with certain uncertainties in this class of computational tasks. The uncertainties are related to the problem of selecting proper argument values (from the interval of their possible variability) for the modelled processes. This situation has a direct influence on the uncertainty of acoustic maps. The idea of applying the interval arithmetic for the assessment of acoustic models uncertainty is formulated in this paper. The computational formalism assigned to the interval arithmetic was discussed. The rules of interval estimations for the model solutions determining the sound level distribution around the analysed noise source - caused by possible errors in the input data - were presented. The application of this formalism was illustrated in uncertainty assessments of modelling acoustic influences of the railway noise linear source on the environment.
Heavy metal (As, Mn, Ni, Sn, Ti) concentrations were determined in soil and plant samples collected in different areas of the railway junction Iława Główna, Poland. Soil and plant samples were collected in four functional parts of the junction, i.e. the loading ramp, main track within the platform area, rolling stock cleaning bay and the railway siding. Four plant species occurring in relatively higher abundance were selected for heavy metals analysis, although in the loading ramp and platform areas only one species could be collected in the amount which makes chemical analysis possible. The selected species included three perennials (Daucus carota, Pastinaca sativa and Taraxacum officinale) and one annual plant (Sonchus oleraceus). The entire area of the railway junction showed elevated concentrations of heavy metals when compared to the control level. It was most pronounced for the platform area and railway siding. The concentration of arsenic, manganese and nickel in plants growing in these parts of the junction exceeded the toxic level. The highest contamination of soil and plants found in the platform area suggested advanced emission process of the analyzed metals from wheel and track abrasion. Literature review showed that the concentration of the investigated metals in soil was generally higher than that found in centers of cities and along traffic roads proving that the railway is an important linear source of soil contamination
The study focused on environmental evaluation of the disposed wooden railway sleeper gasiﬁcation system used for electrical energy production. The aforementioned base technology was referred to the system producing electricity from disposed wooden railway sleepers through combustion. The evaluation was carried out using the LCA technique. The results show that in scope of impact on human health and ecosystems, the technology based on sleeper gasiﬁcation is friendlier to the environment than the alternative technology. The technology of reference produces a lower environmental burden in scope of depletion of non-renewable natural resources. In comparison of the base technology (gasiﬁcation) and the alternative technology (combustion), the end environmental effect shows that in scope of the analysis the base technology, i.e. the technology involving gasiﬁcation of disposed railway sleepers, is more friendly to the environment.
Integration of transport subsystems in transfer nodes of public transport in Poznań based on city railway stations, Poznań, being one of the strongest urban centers in the country, has a significant zone of impact (functional area). A natural consequence of this development model are significant communication issues caused by dynamic development of the suburban area. The solution of those issues is assumed to be basing the public communication system on a railway junction and, on its basis, creating the Poznań Metropolitan Railway. However, to ensure efficient functioning of such a system the need arises to integrate it with other systems of transport using transfer nodes. The aim of this article is to illustrate the potential of creating a polycentric system of multi-modal transfer nodes, based on existing city railway stations (district stations). The study focuses on the perspective of the passenger and the primary research method is the in-depth interview. This enabled to learn the opinion and identify the needs of passengers who use the facilities which are the subject of this study. The study also concentrated on analyzing thee communication behaviors of passengers and analyzing thee functioning of city stations themselves. Additionally, information was also acquired regarding the approximate destination of the passengers’ travel, which further allowed to specify the hypothetical impact range of individual city stations. Results of the study allowed to develop a range of recommendations intended to optimize the functioning of selected city railway stations, from a technical, as well as organization and management perspective. They have the potential to become a basis for developing a concept of sustainable public transport with a metropolitan reach.
Maintaining railway turnout operability is crucial for ensuring railway transport safety. Electric heating of railway turnouts is a significant technical and economic issue. The classical heating is characterised by high power consumption. For this reason, research is needed to optimise the current system. This paper presents results of a numerical analysis and of experimental researches. The numerical analysis was carried out using the ANSYS software. There was conducted a numerical comparative analysis of energy loss during heating performed using two different heaters. Including the classical method and a heater thermally insulated from a rail. In the first step, heating of a working space filled with a substitute snow model was considered. The snow-covered surface area was held within the working space of the turnout. It was assumed that the snow substitute material had thermal properties approximately the same as real light snow. It was also assumed that the material is in the solid state which would not undergo a phase change. In the next step, a real snow model that included the phase change process was taken into account. The energy efficiency and heat distribution in the turnout have been analysed and compared. The experimental researches were carried out in a physical model. The results showed that the use of a contactless heater results in creating a larger area over which emitted heat affected snow in the working space. Consequently, more snow was melted around the contactless heater than the classic one. This experimental observation supported the results of the numerical analyses presented previously.
To study the impact of suspended equipment on the ride comfort in a railway vehicle, a rigid flexible general model of such a vehicle is required. The numerical simulations is based on two different models, derived from the general model of the vehicle, namely a reference model of a vehicle with no equipment, and another model with six suspended elements of equipment mounted in various positions along the carbody. The objective of this paper arises from the observation that the literature does not contain any study that highlights the change in the ride comfort resulting exclusively due to the influence of equipment. The influence of the suspended equipment on the ride comfort is determined by comparing the ride comfort indices calculated in the carbody reference points, at the centre and above the two bogies, for a model with six elements of equipment and a model of the vehicle with no equipment.
The paper focuses on a nonlinear model to represent the mechanical behaviour of a mix coil spring – rubber used in the secondary suspension of passenger rail vehicles. The principle of the model relies on overlapping of the forces corresponding to three components – the elastic component, the viscous component and the dry friction component. The model has two sources on non-linearity, in the elastic force and the friction force, respectively. The main attributes of the model are made visible by its response to an imposed displacement-type harmonic excitation. The results thus obtained from the applications of numerical simulation show a series of basic properties of the model, namely the dependence on amplitude and the excitation frequency of the model response, as well as of its stiffness and damping.
The article investigates the influence of the carbody vertical flexibility on the ride comfort of the railway vehicles. The ride comfort is evaluated via the comfort index calculated in three reference points of the carbody. The results of the numerical simulations bring attention to the importance of the carbody symmetrical vertical bending upon the dynamic response of the vehicle, mainly at high velocities. Another conclusion is that the ride comfort can be significantly affected as a function of the symmetrical bending frequency of the carbody. Similarly, there are improvement possibilities for the ride comfort when the best selection of the stiffness in the longitudinal traction system between the carbody and bogie and the vertical suspension damping is made.
This paper evaluates the level of the vertical vibrations in a railway vehicle carbody generated by the track irregularities and examines the position of the critical point from the comfort perspective. The issue is reviewed on the basis of both a „rigid carbody” model and a „flexible carbody” model, which considers the first two carbody bending modes. The model errors are calculated as a function of the speed behaviour, and the results prove that the comfort performance of a railway vehicle evaluated on the „rigid carbody” model basis are overestimated compared to the ones derived from the implementation of the „flexible carbody” model, mainly at the centre of the carbody. Similarly, a correct estimation of the critical point position in the level of vibrations requires the modelling of the structural vibrations of the vehicle carbody.
The mechanical characteristics of the railway superstructure are related to the properties of the ballast, and especially to the particle size distribution of its grains. Under the constant stress-strain of carriages, the ballast can deteriorate over time, and consequently it should properly be monitored for safety reasons. The equipment which currently monitors the railway superstructure (like the Italian diagnostic train Archimede) do not make any “quantitative” evaluation of the ballast. The aim of this paper is therefore to propose a new methodology for extracting railway ballast particle size distribution by means of the image processing technique. The procedure has been tested on a regularly operating Italian railway line and the results have been compared with those obtained from laboratory experiments, thus assessing how effective is the methodology which could potentially be implemented also in diagnostic trains in the near future.
The practice capacity of a railway junction depends, in addition to the effective operation’s conditions, by the potential risk factors related to the design plan of the railway station. With the aim of an approach based on the “fuzzy sets” it is possible to determine the numeric value of the practice capacity by the logic – qualitative relations between the features of the railway junction and the potential risk factors. This methodology permits to try out the absolute value of a suitable vector β, (less then the unit) for the utilization of the theoretic capacity in conditions of maximum reliability of the system related to the aspect of safety (technique “fail safe”).
The process of wheel - rail interaction is largely determined by dynamic properties of the car, improvement of which is possible by improving design of the bogie and its basic elements. The article analyses and discusses the problems that have arisen in recent years in the course of operation of bogie 18-100. Tribological and mechanical properties of a friction wedge-type oscillation damper are studied.
The paper analyzes the prospects for the formation and implementation of digital data transmission technologies on railways of Kazakhstan, taking into account the potential for the development of high-speed railway transport (HSRWT), as well as new approaches for solving the development problems of advanced automated dispatch control systems (ADCS). It was shown that the solution of these problems is possible by automatization of the train traffic coordination based on the use of the potential of the GPRS data transmission technology. The work further developed models and algorithms used in ADCS of the railway transport. There has been carried out the formalization of the tasks of navigation data transmission for ADCS and for the subsystems of the railway rolling stock movement coordination, including HSRWT using GPRS data transmission technology. Also, the article describes a modernized algorithm for simulation of the GPRS channels operation in ADCS. The proposed algorithm differs from the existing ones by the ability to make predictive estimates for determination of the railway rolling stock location. Also, the developed algorithm provides opportunities for coordination of the trains movement, taking into account the optimization of the GPRS resources use.
The equipment mounted on the carbody chassis of the railway vehicles is a critical component of the vehicle in terms of ride comfort. The reason for that is their large mass, able to visibly influence the vibrations mode of the carbody. The paper examines the influence of the equipment upon the mode of vertical vibrations of the carbody in the high-speed vehicles, reached on the basis of the frequency response functions of the acceleration in three carbody reference points – at the centre and above the bogies. These functions are derived from the numerical simulations developed on a rigid-flexible coupled model, with seven degrees of freedom. As a rule, the results herein prove the influence of the equipment mounting mode (rigid or elastic), along with the speed regime, upon the level of vibrations in the carbody reference points, at the resonance frequency of the symmetrical bending mode. Similarly, it is also demonstrated how the equipment mass and the damping degree of the suspension system affect the level of the vibrations in the carbody.
Automation of data processing of contactless diagnostics (detection) of the technical condition of the majority of nodes and aggregates of railway transport (RWT) minimizes the damage from failures of these systems in operating modes. This becomes possible due to the rapid detection of serious defects at the stage of their origin. Basically, in practice, the control of the technical condition of the nodes and aggregates of the RWT is carried out during scheduled repairs. It is not always possible to identify incipient defects. Consequently, it is not always possible to warn personnel (machinists, repairmen, etc.) of significant damage to the RWT systems until their complete failure. The difficulties of obtaining diagnostic information is that there is interdependence between the main nodes of the RWT. This means that if physical damage occurs at any of the RWT nodes, in other nodes there can also occur malfunctions. As the main way to improve the efficiency of state detection of the nodes and aggregates of RWT, we see the direction of giving the adaptability property for an automated data processing system from various contactless diagnostic information removal systems. The global purpose can be achieved, in particular, through the use of machine learning methods and failure recognition (recognition objects). In order to improve the operational reliability and service life of the main nodes and aggregates of RWT, there are proposed an appropriate model and algorithm of machine learning of the operator control system of nodes and aggregates. It is proposed to use the Shannon normalized entropy measure and the Kullback-Leibler distance information criterion as a criterion of the learning effectiveness of the automated detection system and operator node state control of RWT. The article describes the application of the proposed method on the example of an automatic detection system (ADS) of the state of a traction motor of an electric locomotive. There are given the test data of the model and algorithm in the MATLAB environment.
Railway buffers during the operation are staying in almost permanent contact with each other, creating friction node in the point of contact of two railway buffer heads. In consequence of overcoming track curves, turnouts and unevenness of track, the railway buffer heads moves relative to each other causing friction, which results in its wear. When the wear is excessive, it might be a reason to withdrawn vehicle from service, it causes flattening of buffer head, and in consequence its abnormal cooperation. To avoid this phenomenon the buffer heads should be covered with graphitized grease, but this method has many disadvantages. Accordingly, it was found that it would be beneficial to cover the buffer head with bronze using laser cladding. In this article the metallographic and mechanical analysis of the newly created top layer of railway buffer head are presented. In article the results from tribological tests conducted on Amsler test bench are also presented. Based on test results described in article concluded that the layer of bronze coat on working surface of railway buffer head can be beneficial from operational point of view.