Cold climate regions need railroad ties with improved operational characteristics during the construction and repair of railroad tracks. The aim of the study is to create a technology and equipment ...allowing the manufacture of such sleepers. Low-value soft hardwoods, oily antiseptic, and drying press chamber are needed for the production of sleepers with improved performance characteristics. Technological modes for producing sleepers with high performance characteristics of softwood have been tested using the installation which enables to combine technological operations - drying, treatment, and wood pressing. The resulting sleepers can be used in the Extreme North conditions. The half ties have been laid at Chistye Prudy metro station in Moscow, and the ties have been laid at Scherbenka station on the experimental ring of Russian Railways (JSCo «RZD»). The tests have been carried out for four years in underground railway system and for two years on the ring of Russian Railways. The test results have found that wear of modified sleepers and half ties is about 3 times less than wear of pine sleepers and the average service life of sleepers made of modified wood will be about 50 years. An experimental batch is currently being manufactured.
Curve squeal is one of the most annoying types of noise caused by the railway system. It usually occurs when a train or tram is running around tight curves. Although this phenomenon has been studied ...for many years, the generation mechanism is still the subject of controversy and not fully understood. A negative slope in the friction curve under full sliding has been considered to be the main cause of curve squeal for a long time but more recently mode coupling has been demonstrated to be another possible explanation. Mode coupling relies on the inclusion of both the lateral and vertical dynamics at the contact and an exchange of energy occurs between the normal and the axial directions. The purpose of this paper is to assess the role of the mode-coupling and falling-friction mechanisms in curve squeal through the use of a simple approach based on practical parameter values representative of an actual situation. A tramway wheel is adopted to study the effect of the adhesion coefficient, the lateral contact position, the contact angle and the damping ratio. Cases corresponding to both inner and outer wheels in the curve are considered and it is shown that there are situations in which both wheels can squeal due to mode coupling. Additionally, a negative slope is introduced in the friction curve while keeping active the vertical dynamics in order to analyse both mechanisms together. It is shown that, in the presence of mode coupling, the squealing frequency can differ from the natural frequency of either of the coupled wheel modes. Moreover, a phase difference between wheel vibration in the vertical and lateral directions is observed as a characteristic of mode coupling. For both these features a qualitative comparison is shown with field measurements which show the same behaviour.
•Temperature impacts of Spain’s High Speed Rail network are examined.•Several scenarios are used to explore effects of projected temperatures.•It is shown that buckling events vary strongly among ...different Spanish areas.
With more than 3,200 km of track, the Spanish high-speed rail network is the longest network in Europe and the second largest in the world after China. Due to its geographical location in southern Europe, the entire network is exposed to periods of elevated temperatures that can cause disturbances and severe disruptions such as rail deformation, or in the worst case, lateral track buckling. In this study, the vulnerability of the current Spanish high-speed rail network is analysed in terms of track buckling failures with a Monte Carlo simulation. Downscaled temperature projections from a range of Global Climate Models (GCMs), under three Representative Concentration Pathways (RCP4.5, RCP6.0 and RCP8.5), were forced in a buckling model and particularized for different segments of the network. With that, the proposed methodology provides the number of rail buckles expected per year by assuming current maintenance standards and procedures. The result reveals significant increase in the occurrence of buckling events for future years, mainly in the central and southern areas of mainland Spain. However, relevant variations are found in different climates and time horizon scenarios in Spain. The anticipated buckling occurrences highlight the vulnerability of the Spanish rail network in the context of global warming scenarios. Overall, the proposed methodology is designed to be applicable in large-scale railway networks to identify potential buckling sites for the purpose of understanding and predicting their behaviour.
This paper proposes a three‐phase symmetric converter that is connected between the power grid and the traction network. It can solve power quality problems such as negative sequence current, ...reactive power, and harmonics, thus reducing the interaction between the power supply and the user. Moreover, it supports the continuous co‐phase power supply, which can remove all the neutral sections in electric railways, to improve energy utilization. Its control is simple and suitable for electric railways. We discuss the system configuration in detail, including the topology, the calculation of parameters, etc. In addition, the proposed scheme is compared with the traditional traction power supply system, railway power conditioner, and the co‐phase power supply system based on active power compensator, as well as the modular multilevel converter‐based scheme, respectively, to highlight its advantages. We design the control strategy, which consists of the input side and the output side. In the control part, we focus on the special problems for the application of this scheme in traction power supply systems, and propose the control strategy based on the characteristics of the traction load. Simulation is carried out and a 45 kVA low power platform is fabricated and tested to validate the effectiveness of the scheme. The results show that it has nice performance in solving the power quality problems of electric railways.
The topology of the proposed converter is shown in the black dotted box of Figure. It is connected between the power grid and the traction network, and presents a three‐phase symmetric structure, so it can achieve the balanced grid currents with the same circuit parameters and control strategy for each phase. The input side of the topology adopts multiple structure; a multi‐winding transformer is used in each phase to connect to the power grid, and each secondary winding connects with a BTB converter. The output side adopts the series‐parallel structure. The output of the BTB converter is connected in series, and the output of three‐phase is connected in parallel in order to expand the capacity.
In this paper, we develop a method of real-time train rescheduling on double-track high-speed railway lines undergoing major disruption. As a result, trains approaching the disrupted area cannot use ...the blocked tracks and must be efficiently rescheduled. As most tracks in a high-speed railway station can be shared by trains arriving from both directions, we reschedule both inbound and outbound trains simultaneously by allowing them to share sidings. Based on a space-time network, an integer linear programming (ILP) model is formulated to minimize the train-deviation cost. As the ILP model is difficult to solve for real-world problems, we decompose it into many easy-to-solve subproblems by the alternating direction method of multipliers (ADMM) algorithm. Our model is tested on an abstract representation of the Chinese high-speed railway system to illustrate both the benefit of rescheduling trains in both directions simultaneously and the efficiency of the ADMM algorithm in train rescheduling.
In this work, we consider the problem of scheduling a set of trains (i.e., determining their departure and arrival times at the visited stations) and simultaneously deciding their stopping patterns ...(i.e., determining at which stations the trains should stop) with constraints on passenger demand, given as the number of passengers that travel between an origin station and a destination station. In particular, we face the setting in which demand can be uncertain, and propose Mixed Integer Linear Programming (MILP) models to derive robust solutions in planning, i.e., several months before operations. These models are based on the technique of Light Robustness, in which uncertainty is handled by inserting a desired protection level, and solution efficiency is guaranteed by limiting the worsening of the nominal objective value (i.e., the objective value of the problem in which uncertainty is neglected). In our case, the protection is against a potential increased passenger demand, and the solution efficiency is obtained by limiting the train travel time and the number of train stops. The goal is to determine robust solutions in planning so as to reduce the passenger inconvenience that may occur in real-time due to additional passenger demand. The proposed models differ in the way of inserting the protection, and show different levels of detail on the required information about passenger demand. They are tested on real-life data of the Wuhan–Guangzhou high-speed railway line under different demand scenarios, and the obtained results are compared with those found by solving the nominal problem. The comparison shows that robust solutions can handle uncertain passenger demand in a considerably more effective way.
Measurements of the wheel/rail contact forces are important for evaluating the dynamic behaviour and train running safety. Static and dynamic wheel loads at higher speeds are the key parameters for ...designing sustainable and reliable railway systems. In this study, the dynamic wheel/rail interactions of high-speed trains are evaluated. Actual static and dynamic field measurements were made for better understanding the case for speeds over 200 km/h. The field measurements were carried out on the ballasted track of a high-speed train line for vertical impact load. For the field studies, pre-calibrated wheel impact load detectors were placed on sleepers under the rail foot to analyse dynamic vertical average and vertical peak forces of high-speed trains under service conditions. The field data measurements were also compared and investigated with the theoretical results calculated using the numerical equations suggested in the literature. Finally, field data were used as an input parameter for the developed finite element model (FEM) to analyse the stress distribution along the rail profile.
The optimization of train trajectory and timetable offers two effective methods of energy-efficient operations. Most traditional research optimizes them separately and thus the global optimality ...cannot be achieved. Previous work has mainly concentrated on minimizing the mechanical energy consumption of trains, not the electrical energy. This paper aims to develop an integrated model to optimize the integrated timetable, which includes both the timetable and the train trajectory achieve the minimum electrical energy consumption. The AC power supply system model is first proposed to calculate the parameters of the AC power supply network. Then, a model is developed to calculate various energy consumptions using power flow calculation. Furthermore, an integrated timetable optimization model for minimum total energy consumption of AC railway system is proposed and the optimal integrated timetable is obtained by the proposed hybrid GA-PSO algorithm. Finally, 5 real-world case studies based on the Lanzhou-Xinjiang high-speed railway are presented. The results show that the proposed integrated model can achieve a reduction in total energy consumption for the entire line up to 14.3% compared with the previous optimization model. The hybrid GA-PSO algorithm achieves the best results compared with the results achieved by the GA and PSO algorithms applied along.
•We introduced the development of CR express in China since its birth in 2011 under the Belt and Road Initiatives.•We analysed and compared the fees structures of 5 typical CR express routes and ...related seaborne container shipping routes.•We compared the hinterland patterns of 5 CR express routes under two scenarios with discrete choice theory.
To analyse the hinterland patterns of the CHINA RAILWAY Express (CR express) in China under the Belt and Road Initiative, this paper first reviews the development stages of the CR express. Second, 5 typical CR express routes are examined to comparatively analyse the CR express and seaborne container shipping from the perspective of freight cost structure. According to the binary logit model, the current and the prospective hinterland patterns (choice probability) of two types of products of the CR express are explored. The results show that governmental subsidies for the operators of CR express contribute to decreasing 60% of CR express freight cost. And shippers of IT products are easier to choose the CR express than those of other products. As a result, Chongqing, Chengdu, Zhengzhou and Wuhan have the same opportunities to become the regional railway hub for IT product transport. In Chongqing, however, the high share of other products in CR express market will impact greatly on its competition for the regional railway hub among the aforementioned inland cities.
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