PTC coupled with ECP brakes. ECP can reduce stopping distances by 70%. A PTC trigger would be an ideal add. My FRA project in 2008 included auto-couplers from Sharma & Associates that make up the coupler, air and ECP power with no human intervention. I had added capability to create an "auto consist" that identified the order and orientation of all the cars and displayed on The WiTronix display. That all died a sudden death when Obama took office in January 2009.
" auto-couplers "
That would be awesome and allow the railroads to more closely follow the example of the 'nets packet switching.
You could kick some cars off while passing a siding and use a rail gun to pick some up.
Most of the time freight cars seem to be just sitting around.