Some of the problems we might come across while using the train model could involve:
-The emission from the source has to reach the scatterer, so we would have to remove all the obstructions that might cause interference. Which means we would have to remove the walls/windows of the train and vacuum drain the whole set-up.
-The velocity requirement is very specific.
-we would require a very good break system so our train won’t crash into our scatterer.
We would solve two of these problems if we were to put the train on a circular track close to the desired velocity. There would be no need for breaks and we now have a spectrum of relative velocities if the scatterer is located close to the track.