"Neil Williams" wrote in message
...

Is there a feasible way of locking 4 cars out of use on 321
formations, without having to open the above-door panels and lock each
door out manually? The reason I ask is that there is an element of
that takes place on the 0735ish which starts from Bletchley (with the
rear 4 off the platform but unlocked, such that you can't get to
them), and it seems surprising that they wouldn't think of it. That
said, you don't see 12 cars on any of the Tring slows, and they
probably load the heaviest - is there another short platform, e.g.
Apsley/Kings Langley?

I will be interested to find out if the new Desiros have SDO, as SWT's
ones certainly appear to have some form of it to allow calling at
short platforms on the Waterloo-Reading run.

SWT's Desiro SDO is done by switching out whole units, with the guard
controlling it from the front cab of the rearmost unit - but only if he can
get out onto the platform. This leads to the fairly unusual sight of only 4
cars of a 12 car train being opened at some '8 car' platforms e.g Fareham,
because the 3rd unit's cab is alongside the platform ramp.

IIRC the DfT are insisting on GPS controlled individual carriages as the way
ahead, as is done by Southern, with their annoying 'this is carriage number
n of m' type announcements.

Paul