AIRTRACK, the planned rail link to Heathrow T5, has been given backing
by the government linking up with the Waterloo ” Reading existing rail
route at Staines. First revealed in the Heathrow Airport interim
master plan June 2005, no date has been given for possible completion
but the new T5 underground station incorporates the platforms required.
Any new service would give excellent communications from both the
south and the west, bypassing London and also ensuring a reduction of
road traffic.
http://www.airtrack.org