Currently in Bulgaria, the main railway lines (corridors) are being modernised to increase train speed up to 160/200 km/h, which necessitates adoption of modern European traffic control systems (ERTMS/ETCS, classified as so-called class A systems). The remaining sections continue to operate mainly relay-based systems for ensuring safety of train traffic (the so-called class B systems). These systems include, first, station centralised traffic control systems, most of which are currently route relay-based ones. On the railways of Bulgaria, two classes of route relay-based centralised traffic control systems (RRCTCS) are operated, using respectively, the relays of so called «first class of reliability», and the relays of the so called «not first class of reliability». The inevitable increase in the age of RRCTCSs makes it necessary to assess their technical condition and technical suitability to clarify strategies for their further operation. Such an assessment is difficult due to the lack, first, of statistical data on the failures and reliability parameters during operation as per types of systems and their constituent elements and, second, of manufacturers’ recommendations on the service life of RRCTCS. The service life and residual service life, as well as the useful and residual life of RRCTCSs could, in the author’s opinion, be assessed according to the following criteria: • Electrical and mechanical useful life/wear of the components. • Reliability parameters of the relay components. • Electrical and mechanical useful life or the condition of the external and internal cabling. • Operating costs required to maintain RRCTCS within the range of predefined technical parameters. The article analyses and evaluates the average useful life and the average residual life of RRCTCS based on the first two criteria. It is concluded that neither electrical nor mechanical wear resistance of components is among leading characteristics for assessing useful and residual life. Two approaches are used to consider some of reliability parameters of the relay components: deterministic and probabilistic one, which are based on the «intensity of dangerous failures» characteristic of the relay of the first reliability class. Based on that characteristic, the probability of a dangerous failure of the first-class relays in operation was calculated for 58 Bulgarian RRCTCSs of N-68 type with non-routed manoeuvres, as well as the probability of their safe operation; the latter probability is proposed to be used to calculate the average residual life of the relay, and based on that, to calculate the average residual life of RRCTCSs of that type. By early 2021, the estimated maximum of the latter is 11 years. The consequences of implementing two strategies in subsequent years are considered: a) «nothing is done» and b) «RRCTCS useful life/age management» (based on the program of gradual decommissioning of N-68 type RRCTCSs and of re-equipment of relevant stations). This is also a prerequisite for safety management of train traffic. It is argued that an average useful life of RRCTCS could be estimated as no more than 60 years in operation. Considering additional factors, this period should be understood as a predicted value of the expected time after which the corresponding RRCTCS will reach the limit state and will be decommissioned. The average useful life and the average residual life should be considered the best guideline for the expected age limit for this type of RRCTCS.

The development of high-speed rail requires introduction of new telecommunications technology implemented in an integrated digital technological communication system (IDTC). Features of building such systems comprise provision of switching optical data channels using photonic switches (PS). Switching processes in PS occur at the photon (optical) level. A feature of construction of PS is the use of multi-tier topologies, performed using binary switches (BSs). BS is the simplest switching element with the number of input/output ports equal to one or two. The concepts for constructing PS are based on the technology of the well-known switching circuits using BS whose architecture and topology are assigned the names of their creators (Benes, Spanke, Spanke–Benes architecture, Clos network, etc. With an increase in PS capacity, its structure becomes more complicated: the number of links in the switching circuit, the total number of BSs, the length of switching routes, and the redundancy factor increase. In addition, it becomes necessary to calculate the probabilities of the occurrence of internal blocking in switching circuits, speed of switching optical signals, the value of attenuation of the optical signal in PS circuit, etc. The objective of the study was to develop methods of analysis and synthesis of switching circuits of photonic switches using the example of a circuit of Spanke architecture of a given capacity with calculation of the probabilities of occurrence of internal blocking. The authors used general scientific and engineering methods of mathematical modelling, probability and queuing theory and an example of an algorithm for analysing the structures of Spanke topology with capacities from 4×4 to 128×128. Their topological and probabilistic characteristics (the number of links in the switching circuit, the total number of BS, the length of the switching routes, the probability of occurrence of internal blocking in PS circuits) have been determined. The results of calsulations are presented in the form of tables. The developed methods of analysis and synthesis can be used in the study of similar switching circuits built using BS.

The article substantiates the relevance of comprehensive comparison of various versions of vehicles for off-road container transportation. Following the need to identify a specific engineering solution for development of a tracked road train, it is proposed to use the analytic hierarchy process designed to solve problems associated with determining the priorities of the multicriteria hierarchical structure of the goal, as well as in the presence of heterogeneous criteria or dimensional and dimensionless indicators. The comprehensive comparison of vehicles for off-road container transportation is based on the hierarchy of the mobility features, which is considered decisive for the choice of the priority variant of the structural design. The objective of the work is to substantiate the choice of a priority engineering solution for structural design of tracked road trains for off-road container transportation based on a scientifically grounded hierarchy of the mobility features. To attain the objective, a consistent solution of the following tasks is suggested as follows: development of requirements for vehicles and for a hierarchy of operational properties; analysis of existing structural design and layout solutions and justification of the choice of alternative solutions (specific designs of tracked road trains); conduct of a hierarchical synthesis of criteria based on the results of expert assessment; identification of the preliminary priority of alternative solutions; obtaining indicators of operational properties by methods of simulation mathematical modelling and/or full-scale mathematical modelling; choice of the priority engineering solution. The article discusses the feasibility of using tracked road trains both for transportation of a single 45-foot container and for simultaneous transportation of two 20-foot containers with a total mass of 61 tonnes. The analysis of the existing versions of structural design of tracked road trains has shown that only a vehicle of SVG-701 «Yamal» series, developed in the 1980s and which is not currently manufactured, can provide such a payload capacity. Existing modern articulated tracked vehicles cannot provide transportation of such goods. Hence, the relevance of the task of determining the priority engineering solution referring to structural design and layout of tracked road trains at the present stage of development of technology. Tracked single-hinged articulated semi-trailer road train and a doublehinged tracked road train are proposed as variants of structural design and layout versions of tracked road trains for off-road container transportation. Based on the analytic hierarchy process, opinions of experts and the hierarchy of operational properties, it was established that the engineering solution referring to double-hinged tracked road train should be prioritised. However, due to the small difference between the values of indicators used to select the options, it is necessary to conduct further studies to determine the values of the indicators of operational properties and to re-compare the options considering the results obtained.

The customer focus of cargo carriers plays an extremely important role in the highly competitive market of transport and logistics services, influencing the willingness of companies to be flexible in the pricing policy and other parameters of provision of services when forming a personalised offer to a customer, allbowing to attract a range of new customers, to expand the pool of regular customers based on their brand loyalty. One of the modern tools intended to achieve this goal is the customer loyalty program. The objective of the article is to review and summarise the research and series of recent publications [1–4] by the author and other researchers to substantiate provisions of the customer loyalty program based on analysis and assessment of motives and wishes of customers themselves. To achieve this objective, besides the method of monographic analysis of publications on this topic, the practical part of the research was based on a customer survey. The object of the study was the RZD-Express service for transportation of groupage cargo provided by JSC RZD Logistic company, the subject of the study was the loyalty of private consignors. The task of survey of respondents was to study consumer preferences and motives for choosing such a service, to analyse their willingness to recommend this service to their entourage, the intention to maintain long-term relations with the company, as well as customers’ expectations from interaction with the company. The interpretation of the results of the survey shows the interest of respondents in availability of such a marketing tool as a loyalty program. The study permitted to suggest a system of indicators for the assessment of loyalty program, as well as to put forward proposals for formation of provisions of the loyalty program to improve quality of transport services.

The introduction of low-cost long-distance passenger trains will improve transport availability, expand the geography of routes, increase train departure frequency, resulting thus in growth of passenger turnover and carriers’ incomes. From the standpoint of national economy, the emergence of trains of that kind will contribute to better transport mobility of population, labour market balance, tourist attractiveness of the country and its regions, to increase in GDP thanks to multiplicative effect. As a result of active implementation of state support measures for development of regional aviation, construction of high-speed highways, introduction of car sharing services, in recent years there has been a significant increase in competition in the long-distance passenger transportation market. Each segment of this market requires meeting the needs and expectations of a certain type of customer, reflecting the age, education, type of activity, income, physical condition of a passenger. The competitiveness of a particular type of transportation in the modern world, is based, first, on the widespread growth in the value of time as of a significant resource of human life, and consequently in speed of movement along all the route (from door to door) since life expectancy, in addition to extensive factors (hightech healthcare, healthy nutrition, etc.) evolves at the expense of intensive factors also which certainly include the saving of time for movement. The objective of this article is to describe the business model of a low-cost long-distance railway passenger carrier, to analyse technical, technological, organizational factors that form the model using the methods of economic analysis, observation, and comparison. It is concluded that key conditions for functioning of the model of a low-cost long-distance passenger carrier comprise among others operation of modern energy-efficient rolling stock, flexibility and promptness in development of the route network, identification of the travel frequency and the composition of low-cost trains.

The activities of economic entities operating in a specific territory depends to the highest degree on the action of transport factors comprising the existing economic links and resource provision of those territories. At the same time, it is necessary to highlight a special role of the economic and technological capacity in sustenance of the territorial economy. The economic and technological capacity is an indicator of its material basis as well as of the success of development of the material and innovative base of a particular territory. At the same time there exists a certain cognitive gap in understanding the impact of transport infrastructure on the potential of the territory that makes relevant the continuation of the research to theoretically understand that impact. The objective of this work is to theoretically substantiate the influence of the transport industry on the activities of economic entities of the territories considering the economic and technological capacity of a territory. The integrated approach and empirical and theoretical method used in the work have allowed to conduct the research based on aggregated characteristics of transport industry and open statistical data and to describe the impact there-of on the economic and technological capacity of a territory. To achieve comparable results within the framework of the single national economic and transport system that helps to level the influence of country’s specific features, the analysis referred to the main indices of the activity of territorial districts of the Russian Federation including rates of development of the transport system, general dynamics of the changes in the length of routes and roads and the role of investment in the activity of the transport industry. Results and prospects of the activity of the transport industry were determined regarding territorial interactions of economic entities. The suggested approach to the analysis of the relationship between economic and technological capacity of the territories and transport systems is offered as a basis for further research since being sufficiently universal and once further developed and adapted to relevant conditions it can be decomposed or scaled up regarding study of smaller territorial entities or, on the contrary, of selected countries.

Seven main priorities for development of rail cargo transportation are emerging in the context of an active intensification of scientific and technological development cycles, widespread digitalisation of business processes and an increase in competition in the transport industry. A key element of increasing the attractiveness of rail cargo transportation is its innovative, scientific, and technological development, especially in terms of increasing customer focus. Today, the principles of customer focus in the field of railway transportation of goods are among core factors in competitiveness of railway carriers. This issue is particularly relevant for the Russian Federation that owns a high potential for development of transit routes thanks to its advantageous geographic location. This fact determines attractiveness of railway transportation for cargo haulage customers. The image of future scientific and technological development of railway cargo traffic is formed under the influence of such trends as development of heavy-haul rail traffic, international container transportation, proactive introduction of digital technologies for interacting with customers and monitoring the condition of rolling stock, the provision of services within a single transport and information space, increase in margins and environmental safety of transportation. Digital transformation of the transportation process is among high priorities, which is explained through the importance of maintaining safety of transportation, increasing the transit capacity of the railway network and development of an integrated system for ensuring openness of data to provide customers with all the necessary information. Another priority area serves to increase the economic efficiency of cargo traffic by achieving growth in the share of high-margin goods. Such goods may include pharmaceutical and perishable products, information and communication, electronic and radio-electronic products, etc. An increase in the share of such transportation with a decrease in the volume of coal/oil transportation also has a positive effect on external appearance of the railway company for external investors. The image of the future of rail cargo transportation is largely dependent on various external and internal factors having effect on the industry. Besides, it depends on the emerging macro-trends in the global economy, which determine a certain vector for development of the railway industry. The study, to achieve its purposes, has widely used qualitative research methods and bibliometric analysis of scientific literature, international strategic and program documents of the industry and its companies.

Optimisation of organisation of transportation technological process, in the context of digitalisation and technological progress, is currently an urgent task following its significant impact on efficiency and competitiveness of transportation business. Currently, development of the economic environment requires a significant restructuring of organisational aspect of activity of the transport industry. An efficient transport and logistics process allows us to reduce time associated with cargo handling, cargo delivery, paperwork, etc. Automated storage systems can be mounted at facilities of different area, from largest warehouses of enterprises to compact storage premises. Favourable conditions created so allow to increase attractiveness of the transport industry. Though, the full implementation of information technology requires a systematic and scientific approach to organisation of transportation. Given the trend towards growth in international container transportation, expansion of global distribution networks, as well as development of scheduled transportation systems and the length of routes, which is particularly relevant for Russia, the issue of tracking positioning and controlling over the current state of the cargo becomes an important condition for improving safety and quality of transportation. The objective of the study was to develop a systematic approach to organisation of transportation technological processes for a multimodal transport system based on information technologies. Based on the study of organisation, engineering, technological, infrastructure factors, including those related to transition to electronic document exchange and electronic cargo positioning tracking, the paper offers a basic systematisation of more promising factors. The introduction and use of innovative and effective methods of organising cargo transportation will reduce time required to process cargo transported in a container, and to promptly pass the container through control and supervisory procedures.

The objective of the study is to develop a practically applied methodology and a mathematical model that considers the requirements for transportation of dangerous goods, the technical condition of rolling stock, modes of work and rest of drivers on the routes of intercity transportation, customers’ requirements, and the interests of the trucking company. The functioning of motor pool while transporting dangerous goods is presented as the relationship between transportation of goods and performance of technical maintenance. A proposed approach to planning takes into account the correspondence of the effective number of technical maintenances to the standard required value for a certain period for vehicle fleet carrying out transportation of oil products; compliance of rolling stock output with the volume of oil products that might be delivered and unloaded in the current month; compliance of time of movement of drivers to a specialised resting place on the intercity route with time established for the modes of work and rest. The mathematical model makes it possible to determine output of the motor pool in each month, considering that transportation of oil products, started last month, ends only in the current one. The mathematical model of operating the vehicle fleet during transportation of oil products includes assumptions related to fulfilment of the requirements for motor pool and the driver, which are specified in the Agreement concerning the International Carriage of Dangerous Goods by Road, Decision of the Customs Union Commission dated 09.12.2011 No. 877 (revised on 21.06.2019). Special attention was paid to planning of vehicle operations when volumes of oil products transported are growing during the construction and renewal of roads. The algorithm of the methodology was used to plan operation of motor pool when transporting BND 90/130 bitumen from the city of Omsk in intercity traffic and was the basis for making management decisions on the implementation of the suggested indicators in a motor transport enterprise practice.

Based on the analysis of the route network of railway transport, airports and road traffic, the article provides an assessment of transport accessibility of the resorts of the Black Sea coast aimed at increasing mobility of population and develop tourism The structure of the tourist flow is considered in the context of the modes of transport. More than 50 % of tourists come to the Black Sea coast of Russia by their own cars, which indicates insufficient use of air transport and leads to an excessive load on the highways and the ecology of Kuban and Krasnodar region. Polls have shown that the main reasons for the use of road transport by tourists are the lack of direct air transport flights from some major cities in Russia and insufficient transport connectivity within the Black Sea coast. The article defines the directions for opening of new domestic routes from three regional airports. To solve the problem of transport connectivity, it is proposed to develop maritime traffic using hydrofoils, which will increase the mobility of tourists within the coast area and attract additional tourist flow.

Currently, improvement of public transport of general use is among priority areas for development of urban transport systems. Convenient public transport routes, combined with modern rolling stock and a developed transport infrastructure, allow solving most transport problems and ensure high mobility of residents and guests of a city. The objective of the research, main results of which are described in the paper, was to build an efficient urban public transport network in monotowns of Russia to ensure sustainability of functioning of public passenger transport intended for general use. The article presents an option for solving the problem of functioning of public transport in single-industry towns. Very often, in such cities (with enterprises pronouncedly influencing urban planning), there are two mutually exclusive transport networks, namely, municipal one and contracted one (contracted by an enterprise and intended for shift rotation). As a result, contracted routes are not optimal, municipal carriers suffer losses, transport companies do not meet the schedule, switch to a less capacious type of vehicles, and consequently people are dissatisfied with the work of public transport in the city. To solve these problems, it is proposed to combine the municipal and contracted networks into a single transport network of the city.

The analysis of the accident rate of crane structures indicates that the most common cause of accidents with tower cranes is the wind load. The wind load is considered under working and non-working condition. In the working state, the maximum wind load is considered, at which the operation of the crane with the rated load is ensured. In the non-working state, the calculation is carried out using the coefficient accounting for the change in dynamic pressure depending on the height of the location from the ground surface of the given structural element in the non-working and working states of the crane. However, the regulatory documents as a rule do not consider the random nature of the wind load, although the research materials on changes in wind speed (gusts), proposed in the scientific and technical literature, indicate the interval character of their action. The objective of the research was to study the nature of loading of the tower crane structures, which makes it possible to assess the change in the oscillatory process in the element of the crane metal structure exposed to the action of the wind load. The design scheme proposed in the article considers the change in intensity of the wind load along the height of the crane and the random nature of its change, which together lead to the occurrence of longitudinal, torsional, and bending vibrations. Oscillations of the crane metal structure were considered by the authors as oscillations of an oscillator with given parameters of the oscillation amplitude, system masses (boom and tower), and the weight of the load being lifted. The mechanical state of the system (rigidity and elasticity) was considered as well. Theoretical studies of the system under consideration were carried out in two versions:1) as of an elastic-viscous medium; 2) as of a continuous system. The results obtained made it possible to reveal the physical nature of the oscillatory process and to carry out quantitative assessment of the change in the loading of the metal structures of the tower crane. The theoretical studies allowed to obtain expression, which makes it possible to evaluate the change in the oscillatory process in the element of the crane metal structure exposed to the action of the wind load, which has a random nature of loading.

Due to the increased demands of the world community in accordance with the goals of the concept of sustainable development, supply chain management requires complex decisionmaking models that consider many environmental, economic, and social constraints when implementing various environmentally friendly, green methods and technologies. An effective tool in such conditions is the use of MCDM, multi-criteria decision-making methods. The objective of the research, the results of which are provided in the article, is to analyse the application of MCDM in green logistics and management of green supply chains. The work used a set of methods including system and structural-functional analysis, methods of the theory of fuzzy sets, mathematical statistics, and expert assessments. A general scheme of MCDM implementation is offered and a combined MCDM model is developed for assessing decisions on the choice of green technologies, including a system of indicators for logistics flows, a model for managing logistics flows and a system of tools for green logistics. In the MCDM model, a fuzzy analytical hierarchical process (fuzzy AHP) is used to establish the weight of indicators of logistics flows, eleven MCDM methods are used to rank green logistics tools: SAW, TOPSIS, PROMETHEE, COPRAS, ARAS, WASPAS, MAIRCA, EDAS, MABAC, CODAS, MARCOS. Comparison of the use of various MCDM methods showed a high convergence of the ranking results (Spearman’s rank correlation coefficient is of 0.949). The most consistent are SAW, MARCOS and WASPAS methods, the least consistent are CODAS methods. The results of the design example showed that the most preferable solution is the «use of intermodal technologies and multimodal transportation» (ranked first within all eleven methods), the least preferable solution is the «use of environmentally friendly fuels and lubricants (fuels)» (ranked 12th within 10 methods of 11).

The final part of the article, first published in Rail Business [Zheleznodorozhnoe Delo] journal 110 years ago, introduced to the readers the report of O. A. Struve, presented at the Solemn General Meeting of the members of the Imperial Russian Technical Society on April 15, 1911, on the occasion of the seventy-fifth anniversary of the emergence of railways in Russia, chaired by the Honorary Chairman of the Society His Imperial Highness Grand Prince Alexander Mikhailovich. The second part of the report refers to always relevant issues of calculation of transport accessibility of the regions and connectivity of the country, of cooperation and not competition between railways and water transport, social or commercial nature of investments in transport infrastructure. As figuratively noted the author of the report, «there is no any doubt that each rouble invested in construction of railways while it is a rouble buried in the ground add the value to this ground by much more than this rouble costs». The first part of the report was published in the previous issue of the journal (Vol. 19, Iss. 4 (95)).

A note in Zheleznodorozhnoe delo [Rail Business] journal published in 1911 offered to its readers news about first feasibility study commissioned to build self-propelled cars or, in modern terms, railcars. It was supposed that several models with different engines (including electrical one) will be tested. Despite long discussions about economic efficiency of such vehicles as compared with ordinary multi-coach trains, one could witness rational declarations about their suitability for suburban and city transportation on the routes with smaller passenger turnover.

The article provides a short review of the just published book by Professor Vl. V. Sapozhnikov entitled «Synthesis of Systems of Train Traffic Control at Railway Stations Eliminating Dangerous Failures». The book covers the basics of the synthesis of safety train traffic control systems at railway stations. Control systems at the stage of abstract synthesis are represented in the form of a set of multitudes of finite state machines, the implementation of which excludes the conditions for occurrence of dangerous failures and, accordingly, for occurrence of catastrophic disruptions in work, causing threats to passengers and transported goods. The book is recommended to developers of systems of control of responsible technological processes, computer-aided design systems, testing, technical diagnostics and monitoring of automation devices in transport and industry, as well as to the students, Ph.D. students, academia, specialists in the field of synthesis of control systems.