SEMOR-3D aims to include modelling techniques to overcome the problem of lack of precision in hostile railway environment as can be met in mountains or valleys where the GNSS satellites can lose visibility. In Italy as in the main railway network of centre Europe the percentage rails that runs in mountain area is relevant, so, adopting 3D techniques will extend the use of SEMOR and enhance the worker protection. The present proposal will aim to develop a SEMOR-3D prototype able to improve dramatically workers safety and reducing delay in train traffic.