It is possible to increase the speed of trains on existing railway lines by carrying out reconstruction measures. Such measures may include: electrification, construction of an additional track, modernization of communication facilities, extension of the receiving and sending lines, and the use of inserts on the stage, the introduction of new rolling stock.
   Reconstructive measures to increase the speed of movement on the railway should be designed in such a way that the safety and continuity of train traffic are ensured, the time of passengers on the road is reduced, while ensuring the required transport sizes and the lowest construction and operating costs. To choose the optimal solution to the tasks of designing the reconstruction of the railway is carried out on the basis of mathematical modeling.
   The need to make decisions that do not fully take into account the conditions that determine them, as well as their subsequent impact, is found in all areas of technology, in particular when introducing high-speed traffic on railways. The article proposes a method for solving this problem using a decision support system. It is a computer system designed to analyze and select decisions based on objective data and subjective judgments of the decision maker.
   The essence of the program is to enter a list of possible solutions and specify criteria for comparing alternatives. Next, for each criterion, its type and weight are specified (the evaluation of the importance of the criterion). The requirements for all the proposed options are introduced and a generalized evaluation of each alternative is calculated, taking into account all the criteria and rules. The last step will be to choose the best option for the recons

   In connection with the tendency of population concentration in urban agglomerations, there is an increase in the demand for road transport services. There is an increase in the number of road transport units in cities around the world. As a result, the deterioration of the ecological situation is revealed due to the obsolescence of the fleet, poor quality of fuel and fuel and lubricants, and the peculiarities of engine operating modes in the urban cycle. The ecological situation in cities is complicated by the fact of the high average age of vehicles. At the same time, the experience of European countries shows the prospect of an increase in the number of rolling stock of vehicles, which entails an increase in the environmental load. The deterioration of the environmental situation is influenced not only by the toxicity of emissions from motor vehicles, but also by environmental pollution by noise, vibration and heat.
   According to the hydro meteorological classification, the city of Astrakhan is classified as a polluted industrial city. Emissions from vehicles make a significant contribution to the total volume of pollution. The proximity of highways to residential buildings, the concentration of city traffic on them, regular traffic congestion lead to a deterioration of the ecological situation in the region.
   Taking into account the annual increase in rolling stock in the Astrakhan, it becomes obvious the need to take measures to reduce the environmental load on the urban ecosystem. So, out of the whole range of possible measures, we consider the introduction of the following directions to be the most expedient: optimization of urban public transport routes; widespread use of fuel afterburning technologies; the use of hydrogen fuel for public transport; providing opportunities for the operation of hybrid vehicles and electric vehicles on the territory of the Astrakhan city; expansion of the range of measures in the city to protect against noise and vibration; car fleet renewal; tightening of quality control of fuel, fuels and lubricants, technical condition of vehicles on the territory of the Astrakhan city. This will ensure a decrease in the negative environmental load on the Astrakhan region, increasing the efficiency of movement of passenger and freight traffic.

   Increasing the load-bearing capacity of the sleeper base of the track in the difficult engineering and geological conditions of Siberia is one of the main tasks in the modernization of the eastern polygon. The issue of permissible frost heaving is relevant for the design of anti-spring structures during the construction of new railways, as well as their elimination on existing lines. The existing gradation of permissible frost heaving should be further detailed, taking into account the variety of engineering and geological features of the eastern region.
   Spring thawing is the most dangerous period of the year. As the path thaws, frost heaving decreases. Thawing of frozen soils is accompanied by a decrease in their bearing capacity and the formation of subsidence of the base. As a result, seasonal deformations cause considerable damage to the road infrastructure in Siberia and hinder the smooth and safe movement of trains at set speeds. Therefore, when determining the permissible frost heaving, it is necessary to take into account the spring thawing of the sleeper base.

   The purpose of this work is to find methods to improve the life quality of city residents and guests by improving mobility conditions. According to expert estimates, the total damage due to problems of urban transport systems is 6–8 % of Russia's gross domestic product. Mortality rates due to traffic accidents in Russian cities, compared with many developed countries, are still extremely high.
   The methods of work carried out are: analysis of existing traffic problems in Volgograd, search for methods for solving these problems, practical implementation and evaluation of the quality of the measures carried out through modeling and evaluation of quality and road safety indicators. In Volgograd, over the past five years, only a decrease in the number of dead (from 90 to 58) has been achieved, the number of injured remains relatively stable from 1,200 to 1,600 people per year. In matters of road safety, given the statistics, you need to adopt more European experience than the US experience. The Vision Zero strategy is a benchmark in many countries around the world to improve road safety. A significant role in a large city, both for road safety and for capacity, is played by traffic lights.
   A methodology for improving the life quality of city residents and guests is proposed to improve mobility conditions by creating and developing places of attraction for residents, reducing the dominance of individual passenger transport, ensuring priority to public transport, developing a network of roads and managing traffic lights and road signs in real time.

The organization of the railway transport work is inherently connected with ensuring traffic safety. Currently, it is important to calculate the fixing of promising freight rolling stock with a heterogeneous length on the receiving and forwarding tracks with a variable profile. The existing methodological solutions for calculating the fixing standards require improvement in terms of calculating the number of brake shoes. The paper presents the development of a methodology for modeling and calculating the norms for fixing heterogeneous in length and innovative articulated rolling stock on railway tracks. Schemes of application of forces acting on fixed heterogeneous rolling stock on railway tracks with a “mountain” profile have been developed. The development of the method for determining the combination of forces is proposed due to a more accurate iterative calculation of the resulting force acting on each axis of the fixed composition, and its summation taking into account the wind load. A unified methodological approach is proposed with calculation options depending on the type of rolling stock: the first option is based on the use of known formulas, taking into account the iterative car-by-car calculation of fixing means and the values of average track slopes; the second option is based on the use of refined formulas for determining forces and iterative axial calculation of fixing means depending on the slopes under each axle of the car. The car is used as the calculation unit, in the case of the car occupying adjacent sections of the longitudinal profile of the track, each axis of the car is taken as a unit separately. The interface of the author's program for calculating the norms of fixing rolling stock is presented. The developed methodology and the obtained values of the fixing standards will allow eliminating errors related to human and technological factors, as well as providing an accurate calculation of the number of brake shoes when taking into account the physical data of the fixed rolling stock and the characteristics of the longitudinal profiles of the tracks.

   Currently, there are a number of problems with logistics. Breaking supply chains with high inflation in the world is inevitable. The growth of tension requires considering several options for the transportation of goods at once and assessing not only financial indicators that affect the final cost of the product and, consequently, its attractiveness for the consumer, but also the risks of blocking trade routes. Therefore, the tasks of developing routes for the transportation of goods from China to the Russian Federation are relevant today.
   The article deals with the problems of transportation of groupage consignments from China to Western Siberia. An analysis of the existing routes for the delivery of products was carried out in order to identify patterns in the choice of the type of transport at each technological stage. Multimodal ways of organizing transportation, including the interaction of three types of transport: road, sea and rail, are considered. The main reference points of the studied routes are the major cities of China and the Russian Federation (Shanghai, Vladivostok, Novorossiysk, St. Petersburg, Moscow, Novosibirsk), seaports (Shanghai, Vladivostok, St. Petersburg, Novorossiysk) and railway stations (Vladivostok-Perevalka, Kleschikha, Moscow-Tovarnaya).
   The technological operations performed in the implementation of the supply chains of products for various delivery options are analyzed. Both the general principles of organizing such transportations and their distinctive features are revealed.
   Measures are proposed to increase the competitiveness and profitability of the Russian Railways company in the segment of groupage cargo transportation from China to Western Siberia.

   On the railway tracks of industrial transport, especially on the technological tracks of metallurgical plants, where the use of specialized rolling stock (for example: iron trucks, slag trucks, etc.) is becoming increasingly widespread, that has already led to an axle load 2–2.5 times higher than the standard loads on mainline rail transport. The increased axial load increases the intensity of the formation of depressions in the upper layer under the rail plate and leads to the development of cracks from the impact of fasteners and rail plates on wooden sleepers, which leads to bending of the rail plates and premature decommissioning of both rail plates and wooden sleepers due to mechanical wear.
   The experience of operating railway tracks and switches on industrial railway tracks, along which rolling stock with axial loads of 30–50 tf/axle turns, has shown that some of the rail plates fail long before the expiration of their standard service life, and wooden sleepers and bars have extremely short service lives and are withdrawn, as a rule, not by rotting, but by mechanical wear under the plates.
   Thus, an acute problem in the field of the current maintenance of the railway track upper structure both on the tracks of industrial transport and on the tracks and mainline transport is the increase in the service life of rail plates, as well as wooden sleepers and bars in various operating conditions.
   In this article, the deflections of the rail plate on a wooden sleeper are calculated taking into account the wear of wood and taking into account the variable cross-section of the rail plate. The values of deflections of the rail plate on a wooden sleeper are obtained, taking into account the wear of wood, depending on the applied load. The use of this technique for assessing the strength of rail plates allows you to more accurately determine the margin of safety of a rail plate with different sizes at the design stage.

   The article is devoted to the influence of the creation of an urban consolidation centre on the accumulation of trucks in different scenarios of organizing the input and output of external freight traffic.
   The article is based on the fact that each customer (recipient and sender) acts as a generator, which makes a certain contribution to the total amount of freight traffic. The work evaluates the change in the specific contribution of each customer and the total number of deliveries when the centre is located in the area under consideration, when the external freight traffic is served by road or rail. Calculations showed that in the first case, the technology will not cause improvements in the area due to the concentration of logistics activities, and in the second case, the consolidation centre can be efficient.
   The article formulates the key principle: if the effect of consolidation of goods during the last-mile delivery of the exceeds the effect of freight vehicles concentration near the city consolidation centre, then the project is effective in an area where customers do not coordinate deliveries in any other way.

   Thermite welding used for connection rails, railroad switch elements and railroad repairs. The widespread use of this welding method is associated with the relatively low cost of receiving rail joints. The disadvantage of thermite welding of railways is the duration of the technological process for obtaining railway connections that is about 159...189 minutes.
   This article proposes a technology for grinding thermite welds in a hot state, which makes it possible to reduce the duration of the process of obtaining welded rail joints to 74...76 minutes. It is recommended instead of two grinding operations, preliminary and final, to perform one grinding operation of thermite welds in the temperature range 600…560 °C. The temperature range 600…560 °C is based on the results of the experimental studies described in article. Grinding of welded joints was carried out at different temperatures in the range 850…560 °C. According to the results obtained, grinding in the range of 600...560 °C leads to an increase in the hardness of the tread surface in the weld zone by 2...4 HRC. Measurements of microhardness in the cross section showed that the thickness of the layer with increased hardness reaches 1…1,5 mm. The wear resistance of samples ground in the temperature range of 600…560 °C was higher than that of other samples.
   Approbation of the proposed technology confirmed that thermite welds, which were ground in a temperature range of 600...560 °C, meet the requirements of technical specifications for thermite welding of rails.

   Excavation of pits, trenches for foundations of civil buildings and industrial structures in saturated clayey soils often leads to soil structural change and great decrease in the soil strength and deformation characteristics. In some cases, an artificial sand base is used as a method for construction on saturated clayey soils. However, technology violations and unsuitable material used during construction can be the reason for excess settlement of the erected facilities. The analysis of domestic regulatory literature performed by the authors showed that building codes allow the construction of artificial embankments from materials of various fractions - from clayey to crushed stone.
   The study includes a real example of an emergency situation at gantry crane railways with three hundred meters in length in the town of Tobolsk. The observed excess non-uniform base deformations were up to 240 mm. The artificial base was made using local sand with specific properties such as subsidence and frost heaving, which were not taken into account in the design process. The base properties of the silty sand were analyzed in a laboratory study.
   The purpose of this study was to determine the dependence of the compaction coefficient of silty sand on the loading trajectory and the process of water saturation, as well as to identify the proportion of the subsidence deformation from the final deformation.
   It has been established that the subsidence of an artificial base made of silty sand is about 12% of the actual deformation of the base. In this case, the deformation of the artificial base from the full operational load, taking into account the process of water saturation, is approximately 30%. The dependence of the final compaction coefficient on the initial one is obtained, which can be used to determine the required compaction coefficient of silty sands when they are used at construction sites. An alternative technique for arranging artificial sand bases to obtain the maximum soil compaction coefficient, which is widely used within the region, is presented.

   The durability of the structure as a whole depends on the operation quality of the asphalt concrete pavement compaction performed during the construction of a highway by a road roller. In the course of compaction, the asphalt concrete layer resistance to deformation increases that is due to the continuous cooling of the material, as well as an increase in its density with each passes of the roller. At the same time, the maximum specific pressure under the drum of a road roller is limited by its design parameters. Therefore, each roller can effectively perform the compaction operation within a certain range of physical and mechanical characteristics of the layer.
   The objective of the study is to increase the asphalt concrete mixture compaction efficiency by a smooth-drum road roller by expanding the technological boundaries of the machine's application. To solve this problem, the interaction process of a smooth roller with an asphalt concrete layer is considered. To describe the behaviour of the asphalt concrete layer during loading, the Kelvin model is adopted. Considering the balance of forces acting over the area of contact of the roller with the material to be compacted, taking into account the initial conditions, a system of nonlinear algebraic equations was obtained, which makes it possible to determine the arc length of the roller contact with the material. As a study result of the function of the specific pressure under the roller of the roller to the maximum, an equation was obtained to determine the value of the maximum specific pressure under the roller of the roller. On the basis of the obtained theoretical results, a dynamic simulation of the asphalt concrete mixture compaction with a roller of a roller was carried out.
   Analysis of the simulation results made it possible to draw a conclusion about the possibility of a significant change in the maximum specific pressure under the drum by regulating the speed of the roller. Taking into account the developed technique, an automatic control system is proposed for continuous monitoring of the compaction efficiency. The proposed automatic control system makes it possible to increase the efficiency of the asphalt concrete mixture compaction by the road roller by maintaining the value of the maximum specific pressure under the roller of the roller at the level of the ultimate strength of the compacted layer. Varying the value of the maximum specific pressure under the roller drum is carried out depending on the physical and mechanical characteristics of the compacted layer of the asphalt concrete mixture and is ensured by promptly changing the speed of the machine.

   Rutting of flexible road pavements including the improved asphalt-concrete ones is a problem that is being solved all over the world. For this purpose, research is being carried out in the direction of developing materials and technologies that make it possible to build layers of pavement that are resistant to shear and plastic deformation. They create calculation methods that allow predicting the increase in the rut depth during the operation of the road. Experimental and theoretical studies are carried out to determine the maximum rut depth, based on the conditions for maintaining the transport and operational indicators of the road at an acceptable level. The combination of such studies allows to calculate the required thickness of the pavement from the condition of limiting the depth of the rut by a limit value. In these calculations, the rut depth resulting from pavement wear and residual deformations of the structural layers is compared with a limit value. Limit values are assigned in accordance with the requirements of norms and standards. Analysis of the limit values of the rut depth recommended by different authors and used in the practice of various road agencies showed that these values differ by a factor of 1,5–2,5.
   The article presents a method for calculating the limiting depth of a rut, which makes it possible to limit its values depending on the required values of the coefficient of adhesion of the tire to the surface, the speed of movement along the road section, the depth of the water layer in the rut and the parameters of the roughness of the surface. The basis for calculating the limit rut depth is the criterion according to which the actual value of the coefficient of adhesion of the tire to the surface cannot exceed the limit value. The formulas for calculating the limit rut depth and the calculation results for various conditions of the pavement are given.

   Reinforced concrete is the main structural material in modern construction. It is distinguished by a number of properties and features that must be taken into account for the reliable and high-quality design of various structures and structures. Currently, in the construction market, in addition to traditional steel reinforcement, nonmetallic (composite) reinforcement has become widespread. Low modulus of elasticity, high tensile strength, no corrosion (unlike steel reinforcement), low thermal conductivity, which excludes cold bridges in stone structures, determine the effectiveness of the use of non-metallic reinforcement in stone and concrete structures. It should be noted that non-metallic reinforcement is becoming an alternative to steel due to a significant increase in metal prices. Therefore, the design of fiberglass reinforcement in the form of short rods with reinforcement at the ends as flexible links installed between the layers of prefabricated wall panels is relevant.
   The article presents data from experimental studies of the compliance of a lumped anchor made of fiberglass reinforcement when it is pulled out of small-sized samples made of heavy and lightweight concrete. On the basis of experimental data, a numerical calculation of the crack resistance of a fiberglass anchor working for pulling out is given. To do this, a computational area in the form of a cylinder is selected from the concrete medium at the contact of the concentrated anchor. On the inner surface, which copies the profile of a concentrated fiberglass anchor, the conditions necessary to take into account the joint operation of the anchor and the concrete tile are set. The calculation performed by the finite element method makes it possible to simulate the development of cracks starting at the anchor protrusions and to determine the stress-strain state of the tile concrete under cracking conditions.
   The results of the study are supposed to be used in the design of three-layer wall panels with flexible fiberglass ties.

   Depressurization of underground pipelines transporting water, wastewater, oil products, gas, coal pulp and other substances is fraught with product losses, flooding of territories, environmental damage, deterioration of the sanitary and epidemiological situation, the formation of explosion and fire hazardous situations. Rapid detection, sizing and elimination of product leaks is an urgent task. In the article, this problem is considered as applied to water-bearing communications.
   Based on the proposed physical picture of the outflow of water from the damaged pipeline wall and its subsequent movement in the thickness of the surrounding soil, a mathematical model of the process was obtained. Depending on the water pressure in the damaged pipeline, the size of the emergency hole in the pipeline wall, the depth of its laying and the water permeability of the soil, four options for the possible nature of the manifestation of a leak from an underground pipeline are established: with a concentrated and dispersed exit to the earth's surface, with water resorption in the drainage by adjacent underground utilities.

The article discusses the features, technologies and methods of large-panel housing construction. Special attention is paid to the history and reasons for the appearance of this type of construction. On the example of such countries as Poland, Korea, Germany, the dynamics and results of the development of large-panel housing construction are analyzed. The results of the study indicate that the technology of large-panel housing construction has all the prospects for further development and wide dissemination, provided that energy-efficient and environmentally friendly technologies are introduced. The development of prefabricated construction in the field of multi-apartment housing should be associated with even better coordination of all processes based on BIM technologies, improvement of existing building systems in combination with the elimination of existing shortcomings in technological processes and assembly of blocks. The article presents large-block technology with separation into facade and ceiling panels of medium size, large-panel technology with separation into large facade and ceiling panels, an apartment building built by BBGK Architekci using the technology of prefabricated large-panel structures, the UNICON connecting system of Munitec GmbH, a project of a large apartment building in Korea, which was erected using the Koncz system for high-rise large-panel buildings, a load-bearing system of transverse walls with one-sided overlapping, a load-bearing system of a longitudinal wall with prestressed one-sided slabs, the construction of a residential block based on system modules, etc. The conclusion is made about the important advantage of large-panel construction, which consists in the possibility of achieving consistently high quality of the final product.