When the resolution of your screen exceeds 2048 pixels Microsoft Train Simulator will crash on startup. To avoid this crash copy file D3DIM700.DLL to your installation at default path C:\Program Files (x86)\Microsoft Games\Train Simulator
This patch is contained in msts-widescreen-patch.zip
The developer site for the patch is at https://github.com/UCyborg/LegacyD3DResolutionHack