Do you mean Trainz Ts12 running on Windows 8?
If this is the case, ensure that:
1) Trainz is installed outside of the default location of C:\Program Files (x86)\Auran\TS12 - when prompted for location browse and create the folder in the installer for a location such as C:\TS12 and installed while administrator
2) Run the program as Administrator.
You should have no problems otherwise.
Also what exactly are your problems?
What are the specs of your machine such as video card, processor, disk space, etc. This information is needed for us to help you.
John