2) Logistics : Even if a yard like that materializes, then there is the issue of safety and managing operations. The train will have to enter the yard at a reduced speed, wait for 5-10 minutes for the shunting operation, and a few minutes for doing the brake testing for the combined rake, and again waiting for clearance on the main line before proceeding out. This will eat up close to 20-30 minutes in most situations. And I am sure passengers will not appreciate their train being shunted about in some random yard for half an hour, just after their journey starts.
Managing tickets and UR passengers will also be a problem. As the extra coaches are...
more... being attached in a random yard,only the subsequent stations can utilize these coaches. So reservations etc will have to be managed. And in the return journey, they have sped some time at the penultimate station to make sure that all the coaches which have to be detached in the yard are empty and that there is no one left behind in these coaches. This will only result in accumulating delay, safety problems and mainly lots of headache for the passengers and the railway staff. It's a good idea, but there are so many constraints in implementing it that it ends up giving more problems than utility.
Freights are just loaded once at their source and unloaded at their destination. So they need not worry about all these operations and the job is much simpler for them. But for passenger rakes there are many things that have to be taken care of before the train can operate.