  Railway traffic induces cyclic and dynamic loadings in the track structure
but also in the close environment (Degrande et al. 2006, Fran\c{c}ois et al.
2007, Kausel 2008, Lefeuve-Mesgouez et al 2002, Paolucci et Spinelli 2006). The
analysis of such excitations and their effects (e.g. vibrations, waves, etc) is
fundamental to estimate their level and mitigate their potential consequences
(settlements, nuisances, etc). After a brief summary of the current
regulations, in situ experiments show the variability of the parameters
characterizing the main phenomena (wave propagation into the soil, induced
vibrations, etc). The main dynamic laboratory experiments are then discussed.
They allow the estimation of the dynamic features of the materials (e.g.
resonant column test), but also a simplified analysis of the main phenomena
under controlled conditions (e.g. experiments in a geotechnical pit, centrifuge
tests). The vibratory sources and the impedance ratios between the various soil
layers (or some inclusions) being known, it is then possible to model some
specific or actual configurations through theoretical (transfer functions) or
numerical (e.g. finite elements, boundary elements) methods. Parametric studies
allow the analysis of the propagation phenomena and the attenuation process in
the soil in order to investigate the spatial variations of the vibrations
amplitude in such various configurations. Finally, it may be useful to consider
mitigation or isolation techniques in order to limit the consequences of the
induced vibrations (e.g. vibratory nuisances, radiated noise). Several
experimental and numerical results illustrate this key issue.
