We present in this article a model for the guidance of users in road traffic networks. It is well known since decades that a path with a reliable travel time can be obtained by maximizing, over the different possible paths, the probability of realizing a travel time less than a given time budget. We propose here an adaptation of this approach, in order to introduce robustness in the selection of the optimal path. A robust path here is a path that is not likely to change during the travel, and that admits acceptable alternative detours in case of failure.