The dynamic interaction between the high speed train and the railway track and in particularly, on the contact loads between the wheels and the rail, are very hard to evaluate experimentally. The numerical simulation is bound to play a key role in this context, as it is able to compute these quantities of interest. Nevertheless, the track-vehicle system being strongly non-linear, this dynamic interaction has to be analyzed not only on a few track portions but on the whole realm of possibilities of running conditions that the train is bound to be confronted to during its lifecycle. In reply to this concern, this paper presents a method to analyze the influence of the track geometry variability on the train behavior, which could be very useful to evaluate and compare the agressiveness of different trains. This method is based on a stochastic modeling of the track geometry, for which parameters have been identified with experimental measurements.