Parts of the 700s can boarded off with doorways with fold out doors that lock. Once the lock is used the train automatically shuts of that part of the train.
Oh and the reason they have no handrails in the ceiling is all the equipment removed from coach ends to provide wide inner car spaces meaning the ceiling panels are on latches. So you can't put the handrails in the ceiling without interfering with this.
And for the record the issue of one fault unit and spilting down or boxing in the fault is a red herring. This means you get a late start which means the train had to run fast mixing out stops so there little difference between that and cancelling it for many standing on the platform. In a congested railway spilting one off is hugly disruptive and trying to box a fault in during peak is a fanasty move as even with two drivers it brings things to a stand. sorry but anyone who thinks you can easily fix things on today's railways had never seen the choas a move makes in peak.
I disagree with your last paragraph. We are constantly boxing in or splitting off due to faults on the GN and it rarely causes a late start. It's normally done in places like Cambridge, peterbourgh, welwyn or letchworth yards with more minor faults (cab air con or heating, windscreen wipers etc).
It means that they don't need to send an entire 8 car to Hornsey for repair, a driver can agree to continue their journey and get it boxed in rather than diverted.
Taking away the boxing in option during evening shunting and morning preps will significantly increase complete cancelations rather than short forms or unnoticed boxing in done in time before departure.
I appreciate the 700s will be newer so less prone to 'wear and tear' faults but it's very naive to think they won't suffer from any faults which are easily resolvable by boxing in.
Sorry but can't agree with you on this one.
