The PURPOSE of the paper is to develop the methods and means for adequate modeling of magnetic fields close to underground cables. METHODS. The analysis of a magnetic field involves the determination of electric power system (EPS) modes based on phase coordinates with the application of element models in the form of meshed equivalent circuits with a fully-meshed topology. These models and methods are implemented in the software package Fazonord-APC ensuring modeling of electric power system (EPS) modes and determination of the strengths of the electromagnetic field generated by overhead or cable transmission lines. RESULTS. The paper presents the calculation results of magnetic fields generated by high-voltage cable lines laid in a trench at the depth of one meter. The line is represented by single-core screened conductors with CLPE insulation. Different methods of conductor screens grounding and connection have been considered. The obtained results demonstrate that different methods of screen grounding do not have any significant effect on the strengths of a magnetic field whereas the strengths of the magnetic field grow a little in the case if the screens are grounded at the sending end of the line and connected at the receiving end. The strength of the magnetic field does not exceed permissible limits set for electrical personnel but exceeds insignificantly the permissible norm for residential territories. CONCLUSION. Using the modeling methods of modes and electromagnetic fields proposed by Irkutsk State Transport University the evaluation methodology of electromagnetic safety conditions close to high voltage cable transmission lines has been implemented.

When integrating own generation including emergency power supply sources it is necessary to perform an atypical at the present time complex of calculations of electrical regimes in internal power supply schemes of enterprises including the calculations of steady and optimized regimes, electromechanical transients and power quality indicators. The PURPOSE of the study is to identify the potential risks of accidents resulting in the interruption of power supply of particularly responsible electric receivers when connecting to internal power supply systems of own generation facilities including emergency power supply sources both in parallel and stand-alone operation mode with the power system. The METHODS used include conducting specialized studies of the parameters of electrical modes and a complex of calculations of steady and optimized modes, electromechanical transients and power quality indicators in the DIgSILENT PowerFactory software package. RESULTS. The articles presents the problematic aspects revealed in the specialized researches and integrated modeling of electrical modes in the networks of external and internal power supply of enterprises with own generation and emergency power sources, as well as the measures recommended in order to improve the reliability of consumer power supply. CONCLUSIONS. It is necessary to raise the requirements for the volume of electric mode modeling in the networks of external and internal power supply of enterprises with own generation facilities and emergency power supply sources both at the design stage and during energy inspections in order to to verify the validity of the adopted design decisions.

The Purpose of the paper is to study the starting modes of the belt conveyor electric drive, the mechanical part of which is a complex system of parameters distributed along the conveyor length: weight of the transported load, weight and elasticity of the traction organ, forces of static resistance. METHODS. The theoretical studies were carried out using the mathematical apparatus of linear and nonlinear differential equation systems. The real mechanical system is represented by a simplified dynamic model where the distributed masses of elasticity and force are replaced by equivalent lumped masses. Experimental studies were carried out by modeling methods. RESULTS AND THEIR DISCUSSION. Transient processes are obtained for stator currents, speed, torque and resistance forces on the shaft of the induction motor when the belt conveyor is started. The oscillograms of stroke, speed, acceleration, and incident tension forces for specific sections of the conveyor belt are received. CONCLUSIONS. The developed mathematical model of the belt conveyor allows to study the static and dynamic operation modes of both the drive motor and the conveyor mechanical part consisting of separate sections, on each of which tension forces can be calculated for the starts with different loads.

The article deals with the development of a search algorithm of voltage levels and transformation coefficients of measure points under which the increased value of the net power flow of the active power reduces in the controlled section that allows to minimize the volumes of introduced restrictions of power supply. METHODS. The algorithm is based on electric mode optimization by the reduced gradient method featuring the target optimization function represented by the function that reflects an inadmissible exceedance of the active power flow balance in the controlled cross-section. The algorithm is implemented in PTC Mathcad. RESULTS. On example of the model of a six-node electric network synthesized in the PTC Mathcad we showed a 3.64% reduction in the active power flow balance through the use of the developed algorithm. CONCLUSIONS. It has been found out that voltage regulation in the measure points allows to reduce the values of the active power flow balance in the cross-section and minimize the voulumes of introduced restrictions of power supply required to enter the active power flow balance in the range of permissible values.

PURPOSE. The paper describes the developed software that meets the requirements of the approach universality to storing of the initial information, visualization of power systems with a large number of nodes and connections. This software provides the possibility to create user objects, bind visualization objects to spatial coordinates, and integrate them into various computing environments. METHODS. Taking into consideration the fact that when working with the virtual model of the system visualization can be performed several times and that different calculations can be performed in the system, the visualization process itself does not differ fundamentally in the implementation of various computational procedures. However, it is impossible and irrational to implement all possible computational algorithms in one environment, so it is proposed to integrate the visualization application into other applications and implement a communication channel between them. This concept of the communication channel was named the Bridge (Visualization Engine Bridge). This approach uses a third-party file to exchange the necessary information between the computational and visual applications. RESULTS AND THEIR DISCUSSION. The tested communication channel between the application and the MATLAB computing environment is exemplified by the 18-node scheme. The visualization application initialized the calculation of the steady-state mode by the Newton-Raphson method with all connected communication lines and with one disabled communication line. The obtained results have demonstrated the operating capacity of the proposed approach. CONCLUSIONS. The software has been developed that meets the universality requirement of the approach to information storage, visualization of networks with a large number of nodes and connections. This program allows to create user objects, display graphically connections between the nodes in the form of polylines, integrate into various computing environments and bind data to geographic coordinates.

PURPOSE. A justification is given to the need to increase the completeness and reliability of the analysis of operation stability of synchronous and induction motors (SM and IM) of power supply system (PSS) load nodes and its provision conditions which to a considerable extent determine the efficiency and often operation safety of large industrial enterprises. The purpose of the paper is to develop the methods and tools for reliable real-time simulation in an unlimited interval of the continuous spectrum of normal and abnormal quasi-steady and transient processes in SM, IM, PSS, and in the electric power system (EPS) as a whole that ensures the adequacy of the above analysis corresponding to real conditions. METHODS. The study uses the following methods of scientific research: mathematical and physical simulation, the theory of discretization methods for ordinary differential equations, methodologically accurate parallel implicit continuous integration of differential equations, circuit technology based on integrated microelectronics and microprocessor technology, and IT technology. RESULTS. The paper has revealed and justified the causes of the problem of adequate analysis of the motor load node stability and its provision conditions related to the applicability conditions of the methods of numerical integration of differential equations of mathematical models. To solve this problem a concept has been developed based on a complex approach that provides sufficiently complete and reliable information about the continuous spectrum of normal and abnormal quasi-steady and transient processes occurring in SM, IM, PSS, and EPS as a whole. CONCLUSION. Developed tools enable experimental researches necessary for the adequate analysis of the operation stability of synchronous and induction motors of PSS load nodes and the conditions for its provision.

The PURPOSE of the paper is development of a kinetic model of rolling bearing failures based on the energy criterion of contact strength (life) of elements and a theoretical evaluation of the temperature-strength parameter effect on their durability. METHODS. The methods of analysis and synthesis of the physical theory of technical object reliability and the thermodynamic concept of solids strength are used when constructing a model of parametric failures. The theoretical studies employ the methods of mathematical modeling of damage and destruction processes of the most loaded volumes of surface layer material in rolling bearings elements without additional model or full-scale experiments. RESULTS AND THEIR DISCUSSION. The paper demonstrates the setting of the boundary-value problem for bearings with a rotating inner ring as an example. The formulation of the problem takes into account the effect of the main parameters characterizing geometry of the elements, operation and temperature conditions, contacting surface microgeometry, lubrication conditions, magnitude of contact stresses, properties of element material, etc. on the bearing life. The analytical solution of the problem is presented for the boundary conditions of single-row ball bearings no. 309. The theoretical studies have shown that variation of the temperature only within the operating range can result in the alteration of their service life calculated based on the known dependence by more than two orders of magnitude. CONCLUSION. The methodology for constructing the models of rolling bearing failure by the energy criterion of back-to-back endurance is formulated on the basis of modern achievements in the physical theory of machine part reliability and the kinetic approach to the damageability and destruction of structural materials. When constructing the models of parametric reliability all the main design and technological performance parameters as well as the properties of the bearing element materials are taken into account. An implementation example of the model of ball bearing failures has shown that the possibility of the theoretical study of the influence of various parameters on the value of their project life without any additional experiments distinguishes the proposed kinetic approach from the known identical experimental dependence.

The PURPOSE of this research is to reduce the product changeover time in singular manufacturing with a broad range of products. METHODS. An approach is presented that includes tooling setup unification by the end mill extension length. The calculation model allowing for the tool extension length effect on deflection is designed by the finite element method. To obtain the probable deflection of the end mill and determine its influence on the contour accuracy without calculations a nomogram is constructed, the results of the intermediate calculations are decomposed into quadrants, and the final result of deformation is given with regard to the corrections obtained when solving the finite elements of the models of all the combinations under investigation. RESULTS AND THEIR DISCUSSION. A nomogram for deflection determination has been constructed. An experiment using a 676P milling machine has been carried out to determine a correction factor for end mill deflection. CONCLUSIONS. The use of the nomogram allows to determine tool deflection without calculations and perform tooling setup unification by the end mill extension length that will provide the required precision of dimensions and reduce the product changeover time.

The PURPOSE of the paper is to determine the actual dependence of hole overcut at the EDM drilling of microholes on the main process parameters. METHODS. An experimental and calculation research methods are used to study the multifactorial dependence of the hole overcut. Mathematical modeling of the three-factorial dependence of the hole overcut is performed. RESULTS. Mathematical models of the hole overcut dependence on main process parameters have been received. CONCLUSIONS. The pulse energy has been determined to be the most significant parameter influencing the hole overcut at EDM drilling. The obtained mathematical models allow to select the optimum diameter of an electrode-tool and to specify the optimum electric modes at the EDM drilling of microholes.

The PURPOSE of the paper is to consider the formation of granules from dispersed materials of various nature and aggregate state under their processing in granulators with a flat press matrix; to develop a mathematical model of motion of elastic viscous plastic and fiber-containing dispersed materials in the formation channels (spinnerets) of different cross-sections when processing these materials in granulators with a flat press matrix. MATERIALS AND METHODS. The following procedure is used when developing a mathematical model of material movement along the spinneret: an elementary layer is identified in the volume of material in the forming channel. Then an equilibrium equation of the identified elementary layer is constructed with the allowance for all the forces acting on it and the obtained equilibrium equation is solved. RESULTS. A detailed description is given to the movement of the dispersed visco-elastic plastic and fiber-containing (fibrous) material along the channels of spinnerets of constant and variable cross-sections of granulators with a flat matrix. A mathematical model of the process is developed. The obtained models are compared on the example of fiber-containing charge for the production of granular stabilizing additives of crushed stone-mastic asphalt concretes. CONCLUSIONS. The developed mathematical model can be used in calculations of extrusion type granulation equipment parameters, in particular in flat-matrix granulators of technological lines for the production of granular stabilizing additives of crushed stone-mastic asphalt and for further theoretical and experimental studies.

The PURPOSE of the study is to develop an algorithm of free-form surface partitioning into local domains (individual regions), construction of boundaries between these regions and preparation of the initial data for the formation of an optimal technological process of machining and preparation of control programs for shaping such surfaces. METHODS. Partitioning is based on the mean and Gaussian curvature in the points of a free-form surface. The coordinates of the 3D model grid nodes or the data for NURBS surface construction are proposed to be used as initial data or the analysis of the surface region geometry. The Matlab software package has been used for mesh partitioning. A program has been developed to implement the algorithm and determine the coordinates of domain regions which can be imported into any CAD/CAM programs. RESULTS AND THEIR DISCUSSION. The algorithm allows partitioning of free-form surfaces into flat, convex, concave and saddle-type regions. Modern milling machines can be used to obtain these kinds of surfaces on the parts of various products. These machines must be also equipped with the tools of various sizes and product lines. Their number and machining strategies which determine the toolpaths on the surface regions in relation to the workpiece have a significant influence on milling performance. CONCLUSIONS. The obtained data serve as a basis for tool selection and solving of the optimization problem of toolpath planning under multi-axis end milling depending on the shape of the surface regions.

PURPOSE. The work carries out the analysis of modern processing technologies of fine-dispersed technogenic raw material of electric furnace steelmaking. It is shown that the proposed methods are not widely used in production. The authors propose a processing technology for electrosmelting dust in a rotary hearth furnace with the production of two valuable products - granulated iron and zinc oxide. METHODS. The analysis of technical and economic indicators of the known and proposed technologies for technogenic raw material processing is carried out. RESULTS AND THEIR DISCUSSION. The conducted experiments on the production of granulated iron and zinc oxide allowed to demonstrate the advantage of the proposed technology by the quality indicators of the end products: granulated iron (the content of the main element is not less than 95%, sulfur - 0.04-0.05% by weight) and zinc concentrate (the content of zinc oxide is 86-91% by weight with the minimum content of halogens (Cl, F)). CONCLUSIONS. The technology proposed by the authors has a number of competitive advantages in the chemical composition of the end product as compared with the existing processing methods of technogenic raw materials of electric furnace steelmaking and can be recommended for introduction into production.

The PURPOSE of the article is to study the effect of the main parameters on the kinetics of thickening and washing processes of red mud from low-silica bauxites. METHODS. To study the kinetics of red mud pulp thickening the control method of the pulp level was used in the settling process. The countercurrent washing was studied according to a specially developed method taking into account the sorption properties of the dispersed phase. The parameters of the decanting countercurrent multiphase washing were calculated using the equations derived on the basis of the solution of the system of balance equations. RESULTS. The thickening and washing kinetics of red muds from low-silica bauxites is studied. Consideration is given to the effect of the main parameters on the loss of valuable dissolved matter under the countercurrent washing of red muds and the formation of precipitation zones. The study of the countercurrent decantation washing has showed that a certain washing stage features the maximum value of the clarification rate corresponding to the isoelectric state. The isoelectric state corresponds to the lowest moisture content in the sediment, which is determined by the smallest development of solvate shells of particles in the dispersed phase in the compression zone. The phenomenon of charge exchange of sludge particle surface causes the presence of two zones with relative stability of pulps. CONCLUSION. A method is proposed for calculating the indices of non-closed countercurrent circuits with a complete cycle of multiphase washing in thickening-washing facilities. The nature of the effect of the flow rate of the washing liquid on the dissolved material loss with the finally washed sediment is determined. The influence of red mud pulp dilution on the formation process of condensation zones is studied: it is shown that the average value of R = L:S is (2.2 - 2.4) in the transition zone: 1 for a wide range of initial values R₀ = L: S, it is determined that the increase in Ro leads to the formation of more dense precipitation in the compression zone, while the shortest duration of the period of collective precipitation of dispersed particles corresponds to the isoelectric state of red mud pulps (20 g/l Na₂О_K).

The purpose of the paper is technological testing of introduction of aluminum containing kinds of raw material and industrial waste in the primary alumina mixture with the additional extraction of useful components from them. METHODS. The study uses the thermoanalytical, electron microscopic and mineralogical research methods as well as X-ray diffractometric and structural analysis. RESULTS. A brief analysis is performed on the use of different alumina containing additives in the preparation technology of alumina mixture at Rusal Achinsk JSC. The preparation of mixture with the addition of refractory clay fire brick waste was tested in the laboratory and industrial scale when processing nepheline ores of the Kia-Shaltyr deposit at Rusal Achinsk JSC. Performed technological researches and pilot tests have confirmed that even minimal addition (0.11% weight) of refractory clay fire brick waste in primary alumina mixture allows to reduce the consumption of nepheline ore not less than by 6000 tons per year and ensure additional extraction of alumina. CONCLUSION. Addition of clay fire brick fulfilled in primary alumina mixture allows to decrease the specific consumption of nepheline ore from 3.6 to 2.8 ton per ton of the produced alumina and to reduce the technogenic materials formation volumes by 0.5-0.6 ton per a ton of Al₂O₃. The test results show that the sintering of mixture with the addition of clay fire brick waste results in 91.0-91.5% alumina extraction. It allows both to solve the problem of resource-saving and achieve the ecological effect due to the introduction of spent and dumped technogenic materials in the production as well as reduce their hazardous effect on environment.

PURPOSE. The article presents various methods of drought evaluation, considers the trends of climate variability for the last 70 years that affect the frequency of droughts in the Irkutsk region. METHODS. The data on the yield of wheat as the main grain crop are used to evaluate the probability of droughts. Three groups including random samples, sequences with autocorrelation links and trends are distinguished based on the results of the statistical analysis of the long-term series of wheat bioproductivity. RESULTS. The proposed algorithms allowed to determine the statistical parameters of wheat yield series taking into account their specific features. Having obtained the probabilities of drought occurrence, we distinguished five groups of municipal districts. Based on the proposed methodology of extreme weather event probability estimation, the values of severe drought frequency in 2015 were calculated as well as the damages and possible insurance reimbursements. CONCLUSIONS. It is proposed to use the probabilistic models of drought frequency with the purpose to improve the planning of food production in different natural and climatic areas.

The PURPOSE of the paper is to improve the efficiency of technological equipment in a wide range of loads by optimizing the characteristics of control valves in automatic control systems. METHODS. The usual method for valve characteristics optimization is the method of re-profiling the control valves or the method of nonlinear coupling introduction. The main disadvantage of these methods is the need for design transformations of actuators and inability of adjustment for all operation modes. It is proposed to improve algorithmically the characteristics of control valves in real time. RESULTS AND THEIR DISCUSSION. The effect of hydraulic system features on the operation of control systems is studied on example of a multiple connected automatic control systems (ACS). Input data are obtained as a result of processing the archive of the automated process control system (APCS) of the PGU-450 power unit. The method of the algorithmic correction of the nonlinearity of the flow characteristics of control valves consists in the correction of the regulator’s control signal sent to the actuator in order to displace it further by a value whose magnitude is determined by the reference characteristic discrepancy. CONCLUSIONS. It is shown that being implemented, the proposed method improves the operation quality of automatic control systems. The method can be applied for any type of throttle valves. It means that correction is introduced in the structure of the automatic control circuit between the regulator and the block of digital-impulse conversion, which sends the control signal to devices engaged in reverse control of electric motors rather than the design of the control valve.

The PURPOSE of this work is modeling of motion of charged particles in the electrostatic field of electrodes as applied to the process of flue gas purification. METHODS. The method relating to the mixed algorithms is used for modeling. According to this method each part of a spline is found by field strength sampling and integration of the equations of motion of charged particles in an electrostatic field. This method is used for modeling of the dust particles motion via plate electrostatic precipitator. RESULTS. Numerical experiments on computer modeling of the current of dust particles in the EGAV 1-40-9-6-4 electrostatic precipitator have been conducted. The modeling results agree with the nature of the process of flue gas purification. CONCLUSIONS. An emulator has been developed for 3D modeling of a dust particle current in the electrostatic precipitator between the discharge and receiving electrodes.

PURPOSE. A wide range of methods for estimating unknown parameters of regression models has been developed in the regression analysis. One of these methods is a multiple estimation method that is based on simultaneous minimization of errors by two criteria - the least absolute deviation method and the method of anti-robust estimation. In this case, the estimates of the regression model obtained through multiple estimation are determined implicitly which makes the work with them difficult. The purpose of this paper is to involve the criterion of behavior consistency in order to identify a single parameter vector from multiple estimates. METHODS. The purpose is achieved through the use of mathematical and statistical methods. RESULTS AND THEIR DISCUSSION. The paper briefly describes the problem of multiple estimation of regression models, which is a linear programming problem. This method is shown to give an implicit representation of estimates of regression models. The criterion of behavior consistency is used to select a single parameter vector from a set of estimates. In this case, the problem of multiple estimation of regression models is formulated with simultaneous maximization of the value of the consistency criterion of behavior, which belongs to the class of problems of linear-boolean linear programming. The presented methodology has been used to solve the problem of Krasnoyarsk Railways freight turnover modeling. CONCLUSIONS. The problem formulated in the work provides both the pareticity of the estimated parameter vector in the two-criteria estimation problem and the maximum consistency in the behavior of the actual and calculated values of the dependent variable.

The PURPOSE of the work is to ensure the traffic safety in the proximity to open and unguarded crossings by automatic reduction of the train speed in the proximity to the railroad crossing depending on the current situation at the railroad crossing, without the installation of additional devices at the railroad crossing but through the use of the satellite radio navigation system. METHODS. The methods of automatic train speed control based on the use of satellite radio navigation system GPS-GLONASS are proposed. The proximity zones to railroad crossings and the check points of speed control and reduction are laid on the railway digital map which is stored in the memory unit of the automatic speed control system. The current track ordinate of the train and its speed are estimated in continuous time with the help of the satellite radio navigation system GLONASS. The system control unit evaluates the current location of the train, its speed, makes a decision on the start and end of automatic braking of the train as well as notifies the locomotive driver of the need to intervene in the process of train driving. It also starts the driver’s alertness control device with an automatic alarm (1 long whistle) in the direction of the railroad crossing to alert the drivers of vehicles. The locomotive driver is responsible for making the final decision on the start of speed increase when passing the railroad crossing or on the need for braking before the railroad crossing by service brake application at the end of the automatic reduction of speed in proximity to the railroad crossing to a safe level. RESULTS. Two contradictory conditions must be met at railroad crossings: traffic safety must be provided and railroad crossing capacity must be increased while maintaining the speed of the railway rolling stock. For this case, the system of technical solutions has been introduced for automated speed control at unguarded and open railroad crossings based on the satellite navigation technologies and the state of traffic at the crossing from the side of a motorway. CONCLUSIONS. The function of traffic safety provision is moved from railroad crossing devices to locomotives with the automation of automatic speed reduction in proximity to the railroad crossing and with the possibility for the locomotive driver to perform the final control of the situation at the railroad crossing. The use of this function on railway transport in locomotives will reduce the number of severe road accidents (fatalities, collisions, number of victims).

The authors analyze the use of converters in the power circuits of AC multiple unit rolling stock. The PURPOSE of the study is to carry out a historical review of converters in the power circuits of domestic AC multiple unit rolling stock with commutator and asynchronous traction drives and to propose a new concept of their development. To study rectifier variation dynamics, which is directly dependent on the scientific and technical process in the field of power electronics, the article uses the METHOD of comparative analysis of power coefficients of multiple unit rolling stock converters which is an important power indicator characterizing electric power consumption both on Russian and foreign railways. The RESULT of the study is the analysis of the converters of domestic multiple unit rolling stock with different elemental bases beginning from the first ignitron installations applied on AC electric trains with commutator traction engines of ER7 series of the Riga wagon manufacturer and ending with a power thyristor-based reversible converter of the pilot electric train of ER29 series. Moreover, a study is given to the converters of an asynchronous traction drive based on IGCT-thyristors and IGBT-transistors on example of the pilot electric trains ER9А and ES250 "Falcon". CONCLUSIONS. A promising schematic circuit of an AC electric train with commutator traction electric motors and an IGBT-transistor-based reversible converter is proposed. It increases the power factor by an average of 20 % in the traction mode and regenerative braking.

PURPOSE. The article focuses on modern economic conditions that require the managers to make managerial decisions aimed at fulfilling the contract terms when long-distance cargo hauling. The purpose of the study is to develop a mathematical model of motor transport enterprise (MTE) operation for contract term fulfillment and profit making through the interrelation of commercial and technical exploitation in long-distance cargo hauling. METHODS. The mathematical model is developed within a new methodological conception of current planning of freight MTE operation considering the interrelation of commercial and technical exploitation and allowing to treat the MTE operation when long distance hauling of freight as a probabilistic process. The objective function of the model is the effect of contract terms fulfillment. The economic efficiency of the current planning of MTE operation is estimated by the amount of profit. RESULTS. A mathematical software developed by the authors has been used for practical implementation of the proposed mathematical model. It was found out that the profit under long-distance transportation of goods calculated on the basis of the developed mathematical model is by 10.8% (1281170 rubles) greater than the profit calculated by the applied technique of the technical transportation financial plan. CONCLUSIONS. The developed mathematical model allowed to present the MTE operation as a probabilistic process for which the planned indices of commercial and technical exploitation are calculated for the upper and lower confidence limits of the mathematical expectation of the loaded long-distance cargo haulage with the probability of 0.95 and by the upper and lower confidence limits of mathematical expectation of the weight of long distance cargo shipment.

PURPOSE. The transportation of people, goods and information dissemination have always been a fundamental component of human society functioning. Society is becoming more and more dependent on the development of transport systems, whose main task is to meet the need for people mobility. The article deals with the various criteria-based assessment of passenger transport operation quality. METHODS. The paper provides the analysis of the assessment methods of passenger transport operation quality based on the passenger opinions. RESULTS AND THEIR DISCUSSION. It is shown that in Russia the emphasis is rather on the efficient operation of transport enterprises than on the passengers of public transport. CONCLUSIONS. The methods presented in the article allow a visual assessment of the sections of the street and road network that require reconstruction or other infrastructural solutions that will primarily improve the quality of passenger servicing.