Wheel-rail impact interaction on the high-speed railroad bridges

The paper describes interaction of high-speed rolling stock and railroad bridge deck and proves the importance of adequate model of wheel (mechanism) and rail (structure) interaction. The model must consist of a rail and slabs of the ballastless deck. The paper characterizes the results of computer simulation of perspective rolling stock passing through high speed railroad bridge, that contains the uniform bridge superstructure for Moscow – Kazan line. The paper shows that in case of resonant bridge superstructure vibration the risk of derailment is high because of the decline of the wheel-rail contact force down to zero, which means wheel uplift. Moreover, the impact of the wheel is the result of uplift and the impact value is similar to the impact from impossible damages of wheels or rail on high speed railroad in consequence of which rail breaking occur. This rail breaking is the most frequent reason of derailment. The impact forces are equivalent to the impact of the fresh flat of the wheel and may be more than 300 kN while static force is equal to 85 kN. The vertical contact force is rising from zero to maximum value for 0.002 to 0.004 s after uplift. The computer simulation results show that it is the bridge superstructure resonance, which leads to impact interaction. The rail fasteners rigidity decline causes vertical interaction force decrease during the impact but the derailment risk still exists during vibration of “bridge – track – train” system.

Evaluation of options for strengthening weak bases of embankments of transport infrastructure facilities

The rise in highway design and construction requires ensuring the reliability of these infrastructure projects. This is especially important for construction on weak soils. The number of design solutions is equally on the rise for reinforcing the grounds of soil transport structures. Examples include the use of various types of piles, and structures made of sand, gravel and other draining soils placed in a shell of geosynthetic material. The article presents the results of the authors' work on the substantiation and implementation of various constructive solutions to strengthen the insufficiently strong bases on railway and highway construction facilities (railway lines Losevo-Kamennogorsk, Moscow-Kazan high-speed railroad, Moscow-Saint Petersburg high-speed highway, etc.).

Public Information and Perception of the Environmental Risk about the Works for the City High Speed Railroad Underpass in Florence, Italy

The Florence railway node plays a strategic role in the panorama of the Italian transport system because of its geographical central position. To avoid excessive traffic density and to separate low and fast tracks, a railway city-bypass of 9 Km (7 of which underground) and a new station for the high-speed railway have been planned. Because of the political implications of this decision, it was designed a large opinion poll to understand the current level of information of the citizens on the planned works and to measure their perception of the environmental risks associated with. Given the number of people interviewed, the opinion poll conducted in Florence surely ranks among the most important surveys conducted in Italy on this topic and contributes new insights on the complex links between populations and the environment.

Optimizing High-Speed Railroad Timetable with Passenger and Station Service Demands: A Case Study in the Wuhan-Guangzhou Corridor

This paper aims to optimize high-speed railroad timetables for a corridor. We propose an integer programming model using a time-space network-based approach to consider passenger service demands, train scheduling, and station service demands simultaneously. A modified branch-and-price algorithm is used for the computation. This algorithm solves the linear relaxation of all nodes in a branch-and-bound tree using a column generation algorithm to derive a lower-bound value (LB) and derive an upper-bound value (UB) using a rapid branching strategy. The optimal solution is derived by iteratively updating the upper- and lower-bound values. Three acceleration strategies, namely, initial solution iteration, delayed constraints, and column removal, were designed to accelerate the computation. The effectiveness and efficiency of the proposed model and algorithm were tested using Wuhan-Guangzhou high-speed railroad data. The results show that the proposed model and algorithm can quickly reduce the defined cost function by 38.2% and improve the average travel speed by 10.7 km/h, which indicates that our proposed model and algorithm can effectively improve the quality of a constructed train timetable and the travel efficiency for passengers.

Selecting an Appropriate Express Railway Pavement System Using VIKOR Multi-Criteria Decision Making Model

A gigantic evolution has been brought about in the railway transportation by the emergence of the expressways as the most efficient method of carrying passengers within short and medium interurban distances. Various types of expressway pavements have been offered during the recent years. A considerable amount of the repair and maintenance costs in railroad sector is allocated to the constituents forming the pavements. No thorough and precise research has been so far conducted on the railroad expressways featuring traffics with speeds over 250 km/h and the extant information have merely been trivial changes in the procedures existent for speeds below 200 km/h and these are not deemed of much use and applicability. Thus, the current research paper is devoted to the investigation and selection of express railways pavement system design using VIKOR method. The evaluations indicate that the commencement of the first high-speed train work in 1964 in Japan marked a turning point in the railroad passenger transportation in the world. The development of the high-speed railway transportation is enumerated as an important revolution helping the railroads retake their crucial role in passenger transportation in such a way that it is found overtaking the roadway and aerial transportation and even exposing some airlines to real crisis. The high-speed railroad is undergoing an intensive expansion worldwide and as a safe, sound and sustainable transportation system, it has well proved its role in the social and economic development of the nations.