If you are running automation, you might try the JMRI dispatcher.
Let's say your train approaches an uncoupling position.
As soon as the train enters the detected section (current sense), it will slow down.
To precisely stop that train, a photocell or IR detector will stop the train on a designated spot.
("stopping sensor")
Now, that's only the head end.
Make sure that the coupler is correctly positioned to separate that 40', 50', or X' car.
You may end up with an IR detector at the coupler, count the cars, and stop with logicNG or script.
--
Ken
NYNH&H, Old Colony Division, Cape Cod Branch (1949-1959)
Loconet * JMRI 5.9.2 * OSX,Win10,Ubuntu
Blog: ?
Ken Heywood