Practical or safe? Probably. Practical and safe? I doubt it. On a standard railway platform, leaving late because some passengers hold up the train is a nuisance. With systems such as these, it is lethal.
For the EU one, the critical timing is in detaching from the fast train. It _has_ to happen before the two tracks split up.
For the Chinese one, detaching can be postponed indefinitely, if slow cars in front know it soon enough, and can pull up fast enough. I think that makes this system slightly safer. Worst-case, an emergency command 'all trains to full speed' will 'just' move most passengers to stations a few hundred miles from where they wanted to go.
In either case, I would expect that, to guarantee proper timing of detachment, the doors between fast and slow trains would have to close at least a minute, probably more, before separation. For the EU design, that means long side-by-side tracks. For the Chinese one, it limits the distance between stops of the docking train. One could solve that by allowing two slower trains to dock at the same time, but that increases the risk of collisions tremendously (two half-width trains docking side by side might be the best solution here)
For the EU one, the critical timing is in detaching from the fast train. It _has_ to happen before the two tracks split up.
For the Chinese one, detaching can be postponed indefinitely, if slow cars in front know it soon enough, and can pull up fast enough. I think that makes this system slightly safer. Worst-case, an emergency command 'all trains to full speed' will 'just' move most passengers to stations a few hundred miles from where they wanted to go.
In either case, I would expect that, to guarantee proper timing of detachment, the doors between fast and slow trains would have to close at least a minute, probably more, before separation. For the EU design, that means long side-by-side tracks. For the Chinese one, it limits the distance between stops of the docking train. One could solve that by allowing two slower trains to dock at the same time, but that increases the risk of collisions tremendously (two half-width trains docking side by side might be the best solution here)