Introduction. This article presents a methodology for conducting experiments as well as their results which show the relationbetween the signal range magnitude of the current consumed and the rate of increase in engine oil pressure, the coolant temperature of a power plant diesel engine operating at low temperatures. The relevance of this study is determined by the need to reduce the complexity and time of technical diagnostics of construction equipment, in particular a bulldozer, which is of special importance in the field conditions of the Far North. Current consumption studies have been focused onpositive temperature ranges (from 40 to 90 degrees Celsius). According to the authors’observations,when the ambient temperature changes, the diagnostic parameter under study (the amount of current consumed) is characterized by instability, reading ambiguity and requires correction. The need to warm up the diesel engine of the power pack increases the waiting time necessary for diagnostics. Starting failures of a power pack internal combustion engine lead to the violation of conditions for leak tightness diagnostics of the space above a piston by measuring the amount of current consumed. Therefore, the aim of the study is to determine relationship between the amount of current consumed by the starter and the rate of increase in engine oil pressure, the coolant temperature of a power pack diesel engine operating at low temperatures.

Materials and methods. This section presents the methodology and the results of the experiments. The experiments were carried out with a 6-cylinderdieselinlineengine of the power pack of the Shantui SD 22 bulldozer in the field conditions at subzero temperatures.

Results. Based on the analysis of experimental data, mathematical dependences were constructed between the magnitude of the signal range of the current consumed by the power pack engine and the rate of increase in engine oil pressure, and the coolant temperature.

Discussion and conclusion. Expanding of the functionality of the relative compression method reduces labor content of diagnostic operations included in maintenance No.3(which is carried out every thousand operating hours) for Komatsu D-355A bulldozer by 8%,and labor content of diagnosing the diesel engine power pack itself is reduced by17%.The research undertaken makes it possible to introduce correction coefficients and thereby to ensure the specified measurement accuracy and the reduced complexity and time,toimprove the controllability of technical diagnostics of power plant diesel enginesin construction machinery.

Introduction. The scientific article notes that dynamic coefficients are used for strength calculations of bulldozer units and parts, including the driving wheels. The analysis of the research results shows that the studying of dynamic processes appearing during the movement of various types of tracked vehicles evokes great interest.

Materials and Methods. To analyze the dynamic loads on the driving wheels during cutting and pushing soil, the authors proposed to use dynamic, mathematical, and simulation models of bulldozer. They are based on a comprehensive systemic approach and include the engine, transmission, tracks, working equipment, and the external environment. Using specialized software based on mathematical models and capable to simulate bulldozer movement, blade penetration, chip thickness increase, drag prism growth, and soil transportation, a series of numerical experiments have been conducted simulating the machine operation while moving soil with varying chip thickness.

Results. The results of simulation experiments modeling the cutting and pushing soil process with different chip thickness show that working with a smaller chip thickness (which implies a relatively low load level), the coefficients of dynamism reach significant values - up to 20%. Conversely, when working with a larger chip thickness and, accordingly, under a high load level, the values of these coefficients are insignificant - no more than 3%.

Discussions and Conclusions. Therefore, performing strength calculations for driving wheels of bulldozer caterpillar tracks and maximum loads on the working equipment, the use of dynamic factors is not needed, as strength calculations include safety factors that make approximately 20% of the static loads. Unjustified use of high dynamic coefficients leads to the increase in the metal consumption of the structure, and, as a result, to the increase in the cost of the designed equipment.

Introduction. Vibratory rollers are widely used for soil compaction mechanization in road construction. Due to high values of the driving force generated by the vibration exciter, there is periodic separation of the vibratory roller drum from the ground during oscillations. The study into the features of these oscillation modes is of great importance in determining technical characteristics of vibratory rollers during design.

Materials and methods. The paper presents a three-mass rheological model of the Frame-Drum-Soil system with a deformable drum, the soil mass being equal to 20% of the drum mass. Voigt model was used to model the soil properties. The rheological model allows reproducing different modes of drum and soil interaction: those without and with various types of separation from the soil.

Results. Based on the results of computational experiment with a test vibratory roller, the characteristic features of the drum and the roller frame vibrations, as well as changes in the contact force and soil loading and unloading time for “continuous contact”, “partial uplift”, “double jump” oscillation modes and two-fold oscillations have been established. The expediency of developing promising soil compacting machines operating in two-fold oscillations mode and having an increased compaction performance due to the significantly greater contact force compared to the driving force of the installed vibration exciter and a comparatively long time for the contact force, which provides an increase in the depth of stress propagation and, accordingly, the thickness of the compacted soil layer.

Discussion and conclusion. The paper specifies the criteria for determining the oscillation modes implemented as the “constant contact”, “partial separation”, “double jump” modes or two-fold oscillations. New data are also presented on the values of soil loading and unloading time for various modes of drum vibration, which is important for determining the depth of stress propagation and deep soil compaction.

Introduction. The development of passenger motor transport systems in cities makes it necessary to solve the problem of their organization level assessment. There is a problem of an excessive variety of indicators used for such estimation. This complicates not only comparative analysis of the systems under consideration in different cities but also the development of advancement implications in a particular city. In this regard, the elaboration of the methodology for assessing the level of organization of regular urban passenger transportation, aimed at solving this problem, is relevant.

The purpose of the work is to develop theoretical and methodological tools for organization level assessment of urban passenger transport.

Materials and methods. The paper uses the provisions of general scientific research methods - analysis and synthesis, mathematical statistics, in terms of the analysis of collinearity, multicollinearity and orthogonality of indicators, the theory of transport processes and systems, control theory, methods of expert assessments. The results of field surveys and continuous observation surveys, data from open information systems (the official website of the administration of Orenburg city and Rosstat), “StatSoft Statistics” and “MS Excel” software were used.

Results. From the existing diversity, the use of seven indicators has been justified and their impact on the assessment of the organization level of passenger motor transport systems has been established. The mathematical model developed for this purpose is supplemented with an indicator of system stability under conditions of non-force majeure disturbance. The greatest role in estimating the level of organization plays “The average value of the deviation of bus traffic intervals from the calculated intervals during 24 hours” and “The share of the territory covered by the city route network” indicators.

Conclusion. Theoretical and methodological tools for assessing the organization level of the operation of urban passenger transport systems have been developed, the effectiveness of which has been confirmed by the example of Orenburg city. The organization level was 0.41, with the stability level of 0.302, compared to the acceptable value of 0.876.

Areas of further research focuses on the development of a set of methods for the enhancement of urban passenger transportation systems.

Introduction. The development of transport use in the Russian Federation requires the optimal organization of accident-free road traffic, which is especially important for cities and urban agglomerations with a population exceeding one million. Solving problems with the occurrence of traffic congestion and traffic jams in large settlements such as Novosibirsk is impossible without the timely development of road infrastructure and optimization of traffic management. The most promising methods for optimizing traffic flow management on urban highways and intersections are various modeling methods that help to identify the reasons of traffic congestion on the roadway and to develop measures in order to eliminate them.

Research methodology. Simulation in the AnyLogic environment is one of the promising ways for analyzing and modeling traffic flows. The intersection of Georgiay Kolondy and Okruzhnaya streets in Novosibirsk city was chosen as the object of traffic flow condition analysis and optimization. Objective information on the number of vehicles passing through the intersection during the morning and evening “rush hours” was collected by video recording, a natural way of obtaining data.

Results. The initial and optimized simulation models for morning and evening traffic have been developed at the first stage of research for the selected intersection in the AnyLogic environment. As a result of the optimization experiment, based on the change in the phases of traffic light regulation, it has been found the possibility to increase the intersection capacity by 6.6 %. Establishing reversible traffic on one of the intersection streets and optimizing traffic light parameters will additionally increase flow capacity by another 7.7 %.

Discussion and conclusion. The research results confirm the prospects of using simulation modeling in the AnyLogic environment to optimize traffic light control parameters and the feasibility of implementing reversible traffic on heavily loaded urban highways.

Introduction. The main idea of the circular economy is to maximize the use of industrial wastes in the production of materials and reduce the use of natural resources. Ash and slag wastes (ASW), generated during coal firing at thermal power plants and stored in ash-disposal dumps is a promising secondary raw material for the production of artificial ceramic aggregates.

Materials and methods. This study investigates the physicochemical properties of ASW classified as Class F according to ASTM C618, an optimal composition based on these wastes is determined, aqueous sodium silicate solution being used as a binder. Cylindrical samples are produced by plastic molding and fired at temperatures of 900-1000°C.

Results. It has been established that using 25% aqueous sodium silicate solution as a binder by plastic molding can produce samples with a compressive strength of 7-9 MPa and density of 1200-1250 kg/m³ at firing temperatures of 950–1000°C. These characteristics indicate the material’s potential suitability as an artificial ceramic aggregate for concrete.

Discussion and conclusion. Further research implies testing this composition as lightweight aggregate in concrete.

Introduction. Modern construction deals with the need to conserve natural resources and reduce construction wastes produced in huge amounts annually, up to millions tons in Russia and in the CIS countries. The problem of recycling becomes especially urgent in the context of the restoration of territories affected by military operations, such as the LPR and the DPR, where destroyed buildings pose both an environmental threat and provide a potential source of secondary raw materials. The development of technologies for the production of composite binders based on recycling products, such as expanded clay, is a strategically important task that allows solving environmental problems, reducing restoration costs and construction speed by localizing resources.

The purpose of the study is to develop and provide rationale for the use of composite binders based on Portland cement and finely ground expanded clay concrete (CB) as a mineral additive. The tasks include studying the effect of the specific surface area (400 and 1000 m2/kg) and the mass fraction of the additive (5%, 15%, and 25%) on the physical and mechanical properties of binders, such as normal density, density and strength of cement stone, to determine the optimal composition.

Materials and methods. The following recycled materials were used: Portland cement CEM I 42,5 (New cement), quartz sand and expanded clay concrete (CB). Composite binders were obtained by co-grinding cement and pre-crushed (fraction 0.14-1.25 mm) cement to obtain a specific surface area of 400 and 1000 m2/kg. The research was conducted in accordance with standard test methods in the laboratories of the Belgorod State Technological University named after V.G. Shukhov. The normal density, density, and compressive strength (at the ages of 7, 14, and 28 days) of 3×3×3 cm cube samples were analyzed. Composition determination was based on the structural affinity law, which assumes that the compatibility of components in composition and structure ensures the best operational properties.

Discussion and Conclusion. Experimental studies have confirmed that the introduction of expanded clay concrete into the binder makes it possible to reduce the normal density (water consumption) and increase the strength of cement stone at optimal parameters. The best results were shown by the composition with 15% CB additive, crushed to a specific surface area of 1000 m²/kg (Composition 5), which reached a maximum compressive strength of 76.34 MPa on day 28, which exceeds the strength of the control sample (70.94 MPa). This is due to high reactivity of fine particles, which contribute to a more dense and homogeneous structure. The use of a coarse fraction (400 m²/kg) or exceeding the dosage by up to 25% leads to a decrease in strength characteristics. Thus, it is optimal to introduce 15% finely ground (Sk = 1000 m²/kg) expanded clay concrete, which makes it possible to effectively replace cement without loss of quality and improve the performance properties of the binder.

Introduction. The main problem facing modern cities is the insufficient road capacity within the operating urban transport network due to the increase of traffic intensity observed over the past decades and the growing number of passenger vehicles in traffic flows. The identified problem is relevant for large and major cities across the country and it is caused by the rising level of urbanization. Regular traffic congestion worsens living conditions, negatively affecting both the economic well-being and the ecological situation in urban areas. The traffic capacity of street-and-road network depends on many factors. When addressing the issue of increasing traffic capacity, it is necessary to consider the type of transport facility — whether it is an urban road or a road of general use; if the research object is a straight section, a junction, or an intersection (built at the same or different levels). One of the tools for increasing traffic capacity today is Intelligent Transport Systems (ITS). Along with ITS, machine vision technologies have been widely used for monitoring and control tasks. The purpose of this research is to develop a concept for an intelligent transport system aimed at increasing the traffic capacity of the urban road network through regulation of traffic flows with machine vision technology.

Materials and methods. A section of urban street-and-road network located in the Central District of Omsk has been investigated. One-hour surveys were carried out on weekdays, in the morning and evening peak periods. Data collection involved recording of both pedestrian and vehicle movement for a cross-section. The use of video recording made it possible to determine more accurately the number of vehicles that pass through the cross section. The data obtained formed the basis for building a transport model as a digital twin, taking design solutions, analysis of traffic census and updating traffic light cycles. The PTV Vissim software package was used to evaluate traffic capacity. The microscopic model of traffic flow includes a movement pattern for following a vehicle ahead and a pattern for changing lanes. The results of the simulation include animated traffic movements visualized online, displaying various transport and technical parameters.

Results. The concept suggests redirecting traffic flows to an alternative route with machine vision, artificial intelligence and road signs of 5.15 group. Within the PTV Vissim software, a model of the proposed concept was developed. Simulation results identified the optimal operational time interval for the concept — a 20-minute period. This interval allows redirecting the flows and preventing congestions during rush hours.

Discussion and conclusions. The development of intelligent systems and advanced traffic monitoring and control methods is a vital area of modern urban transport research concerning the increase of traffic capacity. For practical implementation, the proposed concept requires financial support (government funding or grants, private investments), recruiting professional experts and carrying out a more detailed project elaboration.

Introduction. The strength and deformation parameters of asphalt concrete are significantly dependent on its temperature. Over a wide temperature range, asphalt concrete shows elastic, viscous and plastic properties. This leads to the fact that at the macrolevel, with the rise of temperature, asphalt concrete strength declines and its deformation resistance decreases. Under temperature conditions below zero, asphalt concrete behaves as a brittle material, while at temperatures above zero, it should be considered a quasi-brittle material. Consequently, it is necessary to implement microlevel material constants (surface energy, fracture energy, critical stress intensity factors or crack toughness, fracture viscosity) into calculation practice for flexible pavements and content design of asphalt concrete mixes. The analysis of pavement design methods currently used in road construction practice has been performed. The objective of the work has been formulated.

Materials and methods. Information on the concepts of brittle and quasi-brittle fracture by A. Griffith and J. Irwin has been provided, and the criterion of crack growth in the form of the Cherepanov-Rice J-integral has been described. It is concluded that one approach for calculating asphalt concrete layers in pavements at zero and subzero temperatures is the application of A. Griffith’s theory of brittle fracture. The application of brittle fracture mechanics allows to determine the critical stress for the given defect size in the asphalt concrete structure, and conversely, the critical crack length for the given stress. The next stage should involve calculations based on stress intensity factors or fracture energy, applied within the framework of linear elastic fracture mechanics, but taking into the account the formation of a plastic zone with small irreversible deformations at the crack tip. Classical Griffith formulas contain material constants, including the elastic modulus, the magnitude of which depends on the air void content. At the microlevel, air voids act as stress concentrators. Therefore, attention to the air void content in determining the elastic modulus of asphalt concrete used in pavement design is a relevant task with a practical significance. A review of scientific works on determining the energy constants of hot mix asphalt concrete in accordance with the variation of different factors has been conducted.

Results. Critical crack length calculation results for hot mix asphalt based on BND bitumen grades, corresponding to permissible air void content standards, are presented. Analysis of the calculation results shows that the increase in air void content leads to the decrease in the elastic modulus of asphalt concrete and to the reduction in the critical crack length. Calculations have been performed for three values of specific surface energy.

Conclusion. The obtained results allow to make more detailed calculation of the road pavement design.