On the permissible speeds of empty freight cars mounted on 18-100 model bogies

Problem of ensuring motion safety of empty freight cars is most acute in relation to cars on bogies of model 18-100, which is mainly due to operational wear of wheelsets, side frames and bolsters, as well as spring suspension elements. A potential threat to traffic safety arises when a train, composed of mostly empty and lightly loaded cars, moves along track sections that have deviations in the geometry of rail track of III and higher degrees or combinations and sequences of deviations of II degree. The article presents the main results of complex studies: mathematical modeling of the dynamic interaction of the track and empty freight cars of various types of bogie wear based on the Universal Mechanism software and field tests of cars on measuring sections of tangent, easement and circular curves with a radius of 350, 650, 800, 1000 and 2050 m on the section Belorechenskaya — Maykop of the North Caucasian railway. Dynamic qualities and motion stability of empty freight cars of various types are investigated depending on the parameters of the technical condition of the running gears and the deviations of the geometry of the rail track of II and III degrees of various types and combinations when moving in tangent and curved track sections. Authors provide tables and graphs of the dependences of indicators of dynamic qualities and motion stability of universal empty freight cars of various types on the motion speed in tangent sections of the track and circular curves of various radii and easement curves containing artificial deviations of the geometry of the rail track, most negatively affecting traffic safety. Recommendations are given for correcting the regulatory documents of the Russian Railways, which regulate the permissible speed of motion of empty freight cars, depending on the technical condition of the running gear.

Road widening in curves according to the Croatian regulations, German guidelines and the computer simulation of vehicle movement

Road widening is necessary in curves because the rear wheels of the vehicle are usually not steerable and their trajectory is described with a smaller radius than that of the front wheels. The maximum value of the road widening depends on the turning angle, the radius of the curve and the length of the vehicle, the wheelbase and the front overhang. The required road widening increases gradually with a higher turning angle and decreases gradually as the vehicle leaves the curve and continues in the direction. This paper presents the determination of road widening in curves according to the Croatian regulations, German guidelines and computer simulation of the vehicle movement. The road widening determined according to the above mentioned guidelines and regulations for certain design vehicles (truck with trailer, semi-trailer truck and bus), different radii of circular curves (from 12.5 to 500 m) and different turning angles (from 45 to 270°) is compared with the road widening determined by computer simulation of vehicle movement with the Autodesk software Vehicle Tracking.

Interaction Dynamic Response of a High-Speed Train Moving Over Curved Bridges with Deficient or Surplus Superelevation

This paper proposes a three-dimensional dynamic model for high-speed railway trains moving over curved bridges considering the transition curves, circular curves, and superelevation. Key features of this study are to consider the nonlinear geometrical relationships and creep relationships between the wheels and rail, for which the interactive iterative numerical algorithms are developed based on the equations of vertical displacement and rolling of wheelset, and the torsional resonance conditions of the vehicle–bridge system are verified. The results show that the torsional vibration will cause amplification on vertical dynamic response of the beam on the outside edge of the curve. The deficient/surplus superelevation plays an important role in the lateral and torsional angular displacements of the bridge, and the peak of the torsional resonance response can be reduced by adjusting the practical superelevation of the curve. The variations of wheel–load reduction rate and derailment coefficient in the curve section are positively correlated to the deficient/surplus superelevation. The curve radius is the key factor affecting the wear and fatigue of wheel–rail, and when the curve radius is greater than 7000 m, the wear and fatigue can be significantly reduced. Running at a deficient superelevation level can also reduce the wear and fatigue.

Development of universal transport shceme for road traffic optimization in urban conditions.

Introduction. This article addresses the issue of optimizing the movement of road users in an urban environment. The need to resolve this issue arose due to the suboptimal design of the city’s street-road network, consisting in an increase in traffic intensity to limit values and the inability of traffic lights to solve the problems of global demand for vehicle movement. It is also important to address the issue of the movement of ever-increasing pedestrian flows.Optimization of traffic conditions is assumed by the device of integrated transport schemes. The main disadvantage of solving this issue is the limited regulatory documentation that would be applicable in urban environments.Materials and methods. In the article, the authors used, as a fundamental method of analogy, a comparison of the categories of streets and urban roads with suburban highways. Also, the advantages of individual road junctions and their systems and the level of convenience of the streets of Tiumen were analyzed.Results. The results are variants of complex traffic intersections that satisfy the requirements defined in advance regarding various types of intersections with the following indicators: distance between minor streets, number of lanes on the streets, radii of circular curves.Conclusion. Based on the results of this article, it is advisable to consider the third variant of the complex intersection, which is the most promising in terms of the considered parameters.

Horizontal Alignment Security Design Theory and Application of Superhighways

In China, the maximum design speed of highways is 120 km/h, which first appeared in the Highway Engineering Technical Standard (Trial) in 1951. However, vehicle performance, road design, and construction technology have been greatly improved over the past 68 years. To adapt to the development demands of highway design speeds above 120 km/h in the future, it is urgent to study superhighway alignment design theory. Therefore, the horizontal alignment security design theory of superhighways was developed in this paper. First, the definition, classification, and construction mode of a superhighway and suitable vehicles of different grades are presented. Then, the lengths of straight lines were limited to reduce driving fatigue. Next, the minimum radii of circular curves were calculated based on driver characteristics and stress analysis of operating vehicles. Finally, the minimum lengths of transition curves were calculated based on the centrifugal acceleration of the operating vehicles, the travel time, and the passenger visual characteristics. The calculation and analysis results show that the superhighway linear features conform to the vehicle operating characteristics, and can ensure the safety of driving.

S-Shaped Transition Curves as an Element of Reverse Curves in Road Design

A road designing involves horizontal and vertical alignment. The horizontal geometry is formed by straight and curvilinear sections that are traditionally formed using circular and transition curves (mainly the clothoid). Different geometric systems that are designed using circular and transition curves are between others circular curves with symmetrical or unsymmetrical clothoids, combined curves, oval curves and reverse curves. Designing these systems is quite complex. Therefore, so-called S-shaped transition curves are an alternative to traditional approaches. These curves are known from literature and are modern geometric tools for the shaping of reverse curves. The paper analyses the basic geometric properties of these curves as well as compare to the geometry of the appropriate geometric systems, which are formed with clothoid or using S-shaped transition curves. In addition, a procedure for designing reverse curves using S-shaped transition curves was proposed. Another research topic was the comparison of the analysed reverse curves (created using polynomial transition curves) with traditional curves (created using the clothoid). The results of the studies, despite the noticeable differences in the geometry of the compared components, confirm the practical usefulness of the S-shaped transition curves for designing the geometry of the route.

Improvement of Characteristics of the Railway Direction Kharkiv-Dnipro with the Purpose of Introducing the high-speed Passenger Traffic

The high efficiency of high-speed rail transport contributes to its development both in the service sectors and in the construction of devices for servicing high-speed trains, in particular, track development. At the same time, it is necessary to take into account the obvious problems that accompany the process of reconstruction of railways during the transition to high-speed passenger traffic. Among them, the presence of small radii of circular curves, an insufficient length of straight inserts and transition curves should be noted. In this paper, it is proposed to consider small-radius curves located close to each other as one common module when reconstructing railways with the aim of introducing high-speed passenger traffic. The implementation of this approach will allow solving one of the main problems - straightening of the railway section. This will increase the speed of passenger trains and reduce travel time by reducing the length of the route. The article deals with the task of reconstruction of modules consisting of three adjacent curves, which occur when improving the characteristics of the plan of the Kharkiv-Dnipro railway direction.