In message .com, John
B writes
Except the trains are formed with UNDMs at the inner ends of the units
and therefore have no driving cabs (Apart from the shunting panel, of
course). 95 stock doesn't have any double ended 3 car units.

How easy/difficult would it be to create a double-ended unit using
existing cars?

I'm not that familiar with 95 stock but on 73s (which I am more familiar
with) it would not be even considered. For a start you would lose a
full train in the process as you would need the driving cab from each
end (2 units) to make up your little train. Then you would leave the
other 3 cars sat around taking space up that now couldn't be used.

Tube stock is formed into fixed units (either 3 or 4 car) with
semi-permanent couplers within the unit and the electrics and other
jumpers hard wired as they are designed to be only split in the
workshops, and therefore can't be re-marshalled on a whim. Equipment is
also spread throughout the train (ie, the compressors are actually in
the trailers) as there is a shortage of space. It's highly likely that
the cars marshalled into this little train would have to have some sort
of wiring modifications and no doubt the software would have to be
rewritten and then debugged as the train currently expects to find 6
cars out there.

Another issue here is that the trains have everything duplicated for
backup in case of problems. In the case of our 3 car 73 stock for
example, (the ones with two cabs, known as double ended units) this
means that the trailers have been fitted with 2 compressors to comply
with this and thus can operate as a 3 car unit, so no doubt any 95s used
would have to be similarly modified. Now, before anyone suggests that
it might be a good wheeze to steal a 3 car double ended 73TS for this
mythical exercise, I should also add that there are restrictions where
various trains can go; and due to the fitment of static converters at
refurbishment, 73TS is now restricted to the Piccadilly and other
limited excursions where appropriate signalling immunisation has taken
place.

Then you have another problem in that you would now have a unique train
(so, what happens when it needs serious work done, do you have a second
short spare to maintain the service?). If you do have service problems,
that train then couldn't be used anywhere else to maybe fill a gap in
the service and then bring in a later train in to recover the MHE
service. Allocations of trains to workings at depots (yes, each working
is allocated a specific train at the start of the day) would be
complicated as you have different types of train involved and it can't
be rotated to even out the mileage either.

These are just a few random thoughts why I think it would never happen.
--
Steve Fitzgerald has now left the building.
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