In message .com, Bob
writes

Both the DfT and the Airtrack forum believe the scheme could be
operating in 2011, in time for the London Olympics in 2012.

I've never understood how more trains could be projected down the line
between Barnes and Twickenham, given the frequency of the existing
services and the constraints of three level crossings on the way.

Would it mean diverting the Windsor service round the Hounslow loop -
and would that in any case free up enough slots?

--
Paul Terry