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The use of railway transportation for satisfying the transport needs of goods in Mexico is less intense than in developed countries, such as Germany. Mexican performance measures based upon the railway length per capita (intensity), or the railway length per square km of the country surface (density), are well behind from corresponding indicators for Germany, in such a way that the length of the railway infrastructure of Mexico should be, at least, doubled in order to reach a comparable intensity rate as that of Germany. In this paper, the benefits from transferring the whole transportation of goods from road to railway, is discussed. The benefits include a remarkable reduction in energy consumption and CO2 emissions. The feasibility for the electrical infrastructure to provide the necessary energy is further shown, while the economic feasibility of such situation is analyzed on the basis of the federal budget of Mexico. According to these estimations, the investment in railway infrastructure is feasible, while the electrical installed capacity is enough to satisfy an all-electric system.
Algorithms to estimate ultrasonic testing method based on the integrated use of indicators of reliability and accuracy are presented, and built according to the nature of techniques, features of their application and evaluation purposes (comparison of techniques, introduction of new methods, test procedures, etc.). On the basis of the main revision of ISO 5725-1, 5725-2 the estimation of reproducibility and repeatability of measured characteristics determine the design of reflectors and real defects, and thus the reliability of non-destructive testing, including ultrasonic inspection of railways.
Usually, geometric irregularities are considered as the main cause of ground vibrations from trains. A varying stiffness of the track, the track support and the soil can also generate ground vibrations. The regular stiffness variation of the track on and between the sleepers results in a deterministic dynamic axle load. The random stiffness variation of the track support yields also dynamic axle loads. The dynamic axle loads are generated by the varying wheel displacements under the static axle load by the acceleration of the unsprung mass of the rail vehicle. The random stiffness variation has a second effect. The pulses from the passage of the static axle loads are superposed regularly to the quasi-static response, but also irregularly to yield a “scattered” part of the axle pulses. The same holds for a random variation of the soil stiffness. All these effects of stiffness variations have been calculated by wavenumber-domain multi-beam track models, a random finite-element soil model and the superposition of axle impulses in a stochastic simulation. The results are confronted with many measurements at different sites. It is concluded that the stiffness variation of the track and the soil generate an important ground vibration component near railway lines.
A simple and fast prediction scheme is presented for train-induced ground and building vibrations. For the emission, finite-element boundary-element or multiple-beam-on-continuous-soil models of the track have been analysed and approximated by faster track-on-Winkler-soil models. The vehicle-track interaction due to irregularities yields the excitation forces. For the transmission of waves in the soil, the wavenumber integral of the compliance of layered soils has been evaluated. The calculation time is reduced for the prediction by using the solution of a homogeneous half-space with a frequency-dependent wave velocity (the dispersion) of the soil. For the immision, many 2 and 3-dimenisonal finite-element building models have been investigated, and a good approximation has been established by a 1-dimensional soil-wall-floor model. In addition, the axle sequence of the train, the quasi-static and the “scattered” response of the soil, and the wave propagation from a tunnel to a pile foundation of a building have been included.