I worked for a while for a guy that loaded new cars onto the train cars at an assembly plant.
It turns out the have little connecting ramps from train car to train car.
You drive into built in "ruts" at the back end of the train and just floor it.
Hands off the wheel the ruts will keep you aligned.
Springs go full lock up and down.
Most guys just count the train cars they have gone through and let off two before they need to stop.
But, of course, some like to push it a bit.
A 50 train car "stack" can produce quite a ride.