| dc.description.abstract | Over the past several years, solution of issues of quality of development, modernization, reconstruction and maintenance of international railway corridors has been in focus, considering the changing needs of an individual country’s residents and common needs of railway users in general. The development of railway transport systems influences the quality of life in separate countries and regions, as defined by complex equilibrium of economic, social and political factors. The railway transport sector in countries in Central and Eastern Europe is outdated in the technical, economic, technological and organizational sense, lagging far behind modern and efficiently interacting railway transport systems of Western and Northern Europe. Their main weaknesses include low train speeds, different conditions for the use of railway networks in different countries (differing requirements for infrastructure, projecting standards and rolling stock), low-level services, noise and vibration, insufficient level of traffic safety and environmental protection. The problem of increasing train speeds is of key importance. Development of a joint European high-speed railway network has been started, and Lithuania should join the system as well. The main goal of the Lithuanian railway sector is to increase speeds of passenger and cargo trains on main lines from the current 120 km/h for passenger trains and 90 km/h for cargo trains. The increase of train speeds is not a technical issue only – as modernization of infrastructure requires extensive investments, it becomes an economic task, as well. Modernization and development of the existing railway infrastructure requires immense investments, which have to be based on technical and economic calculations. Implementation of the Lithuanian railway infrastructure and development program will require a minimum of about 305 million litas annually in the 2001–2007 period. The goal of the work is to increase speeds of cargo trains to 100 km/h and that of passenger trains to 160 km/h. Growth of train speeds leads to reduction of passenger or cargo travel time, which produces an economic effect. Railway tracks consist of straight sections and curves. Curves make between 20 and 35 percent of the overall railway length. Increase of train speeds on curves intensifies forces, which act on the track and train passengers, and reduces safety of all kinds of train traffic and the level of passenger comfort. This is due to the existing small curve radius and rising outer rail, which is outfitted in an effort to reduce centripetal and centrifugal forces. Therefore, the increase of train speeds leads to stricter requirements for road construction and maintenance on curves. A key engineering task is to determine curve parameters after changes to the railway track utilization conditions, which depend on a specific country’s topographic conditions, the ratio between the traffic of passenger and cargo trains, economic, social and political factors. On curved railway lines used by both cargo and passenger trains, it is necessary to verify the ratio of cargo and passenger train speeds. The cost of increasing railway curve radius is equivalent to the cost of constructing a new railway line, therefore, it is important to determine whether it is more expedient to reconstruct existing curves or build new lines for passenger trains only. (In Lithuania, railway transport accounts for merely 2.7 percent of passenger carrying among other means of transportation, therefore, building of new lines for passenger traffic only is not projected). Meanwhile, traffic of passenger trains determines most requirements set for railway infrastructure (speed limits, station equipment and parameters of track plan and longitudinal section) and prospects for expansion of the rolling-stock depot. All reasons stated above determine the relevance and validity of the doctoral dissertation. Aim and tasks of the work The aim of the work is to determine the influence of railway track parameters upon train speeds on curves, as well as to analyze and propose rational solutions for increasing train speeds on main lines of Lithuanian railways. The following tasks were set out to achieve the aim: • To analyze and assess the experience of foreign countries in similar researches and specify it to meet the specific needs of Lithuanian conditions; • To analyze main factors influencing train speeds on curves of railway tracks; • To develop an analytical algorithm for the selection of railway track curves to define the influence of existing parameters of curves upon train speeds. To design improved methods for researching existing railway track curve parameters in an effort to increase train speeds; • To carry out pilot research of selected railway lines in order to analyze factual train speeds on railway track curves and determine the effect of existing curve radiuses, rising outer rail and positions of curve on the line upon them. To present an analysis and assessment of research data; • To propose mathematical models for solving tasks to increase railway speeds on existing railway lines; • To determine the economic effect caused by the implementation of research results. Scientific novelty and originality of research The work discusses main factors influencing train speeds. With the help of a detailed analysis of the experience of foreign countries in railway development, modernization, reconstruction and maintenance and research of priority railway lines in our country, the author has developed an algorithm for grouping railway track curves, which enables to determine, for the first time, the volumes of work for reconstruction of railway track plan curves and the necessary investments required to satisfy users’ needs and improve life of the population. Under the proposed methods for researching railway track curves, the author researched for the first time in Lithuania and summarized – with the help of the „TRAUKA“ software – the factors defining curved sections of railway tracks that are necessary for improvement of solutions for train speed increase. The author suggests applying mathematical modeling when addressing tasks of optimizing parameters of railway track curves in modernization of railway lines. The economic effect of travel time savings for passengers has been calculated. Main factors restricting train speeds on mixed-traffic railway lines are small-radius flat curves of railway track plan, their parameters and the position of the curve on railway line. Therefore, special research was carried out to substantiate parameters of railway track curves for reconstruction of existing railway lines to facilitate higher train speeds. The author suggests that problems arising with the increase of train speeds should be addressed through assessment of railway track curve radius, rising outer rail, curve position on line and factual train speeds determined with the help of the special computer software „TRAUKA“. The author reasons that economic issues of railway reconstruction should be solved and decisions should be made using the analysis and conclusions of research of railway track curves. Research object and methods The dissertation analyzes the influence of railway track curve radius, rising outer rail and position of curve on line upon projected train speeds. Two priority railway lines in Lithuania were analyzed by the aspect. The abovementioned object of research was analyzed using theoretical, analytical and mathematical statistical methods. Computer software „TRAUKA“ was used for experimental research. Significance of scientific work The significance of scientific work performed is that the proposals were taken into consideration during modernization of main lines of Lithuanian railways, which led to saving of expenses related with travel time economy, and volumes of railway track curve reconstruction are linked with topographic conditions of Lithuania and specific characteristics of railway traffic are assessed (the share of haul volumes and tonnage of passenger trains in the general tonnage is forecast). | lit |
