Creating terrain surface from mesh

Use 'Create from elements' tool (Q 5) in Terrain Model task. Select the mesh to make the terrain. I am not sure what you mean when you say you created the mesh from the ICM model though.

This mesh comes from a corridor with Design Stage set to Final_Top_Mesh. I use Model Interoperability tools to export the corridor mesh to separate file.
When I try with "Create from element" the program crashes

Create a new empty file, reference the corridor into the new file and create the terrain from the mesh. You do not need the model interoperable tools - those are used to create an ICM (I-model) for use with (for example) Trimble Business Centre. I suggest that you log a service ticket regarding the crash.