SETUP: To add trackmarks in surveyor for driver commands such as 'navigate/drive to' etc, add trackmarks at the end of the rear invisible (red) tracks. Set the trackmark radius at 25 in order to maintain the correct stopping position in the shed for long locomotives. If you wish to continue with driver commands after waiting in the shed you need to wait for a minimum of 20 secs, to allow the doors to close, before commands to leave the shed.The doors can be opened by AI driven engines entering or leaving the shed. I have tested it with various BR locomotives from class 08 up to class 66. Any engine larger than the class 66 will be too large to operate the doors from inside the shed. There is invisible (red) track (which does not show up in driver) attached to both the front and back and you should attach your own choice of track to the front points only. DO NOT attach any track to the invisible (red) track at the rear. This is there because AI drivers do not drive right to the end of the track, they stop short, and the extra invisible track is to make the length correct for them to stop at the end of the shed. I have left the roof slightly transparent. If you zoom in with the mouse (with a little juggling of the angles) it is possible to observe the loco movements inside the shed. This asset is based on an idea from a tutorial originally by Andy Smith.