Andy wrote:

But the SWT webchat from February (http://www.southwesttrains.co.uk/
archive.aspx?p=3) implies than only some of the suburban services will
be lengthened (see below). The longest trains are unlikely to run for
the full peak, just the busiest trains.

Question: 132

Can you tell us anything about planned increases in the train fleet to
allow for suburban train lengthening, to make use of Network Rail's
platform lengthening over the next few years? (The latter project is
documented quite thoroughly in NR's December update to the CP4
enhancement plan.)

Answer:

We are in discussion with the Department for Transport about
lengthening of some of our services from 8 to 10 cars. This is a
confidential negotiation and we are sorry that we cannot give any
details in the moment.

Funnily enough, I knew that - it was my question - and the answer was
basically as expected, and the same as earlier webchats!

But going by the NR Mar 2010 enhancement plan - which is much more detailed
than the webchat response, as I intended to point out...

"10-car operation on all suburban services
Additional vehicles involved 140
0700 - 0959 capacity impact 19,200
0800 - 0859 capacity impact 7,300

That implies extended trains right across the peak 3 hour period, with a
slight increase in the 8-9 period. I can't see a practical way of running
the inner suburban routes at max length in the peak flow direction only?

Paul S