Ras R’Mel Moroccan tunnel is a 2.6 km long and 60m² section single track railway tunnel. It was excavated in a complex geological context of highly heterogeneous and highly deformable soft rock. The purpose of this paper is first to describe the methodology used for specific design of support and lining. The deformation monitoring process applied during construction will then be detailed, and an analysis of the deformations measured will be given, making a comparison with design calculations results. Main concerns were potential face instability and high tunnel deformations.