Plans to build a high-speed railway link between London's Heathrow and Gatwick airports have emerged to increase airport capacity without the controversial third runway at Heathrow.

The idea is to operate the UK capital's two main airports in a co-ordinated manner as a single "virtual hub", dubbed Heathwick, and transfer passengers between the two locations with a dedicated train line.

This would cost around £5 billion ($7.8 billion) to build, according to industry sources.

The UK Department for Transport (DfT) said that it is evaluating "whether it might be possible to create a 'virtual hub' by improving connectivity between existing airports" as part of a review of the coalition government's aviation policy. The proposal would be discussed alongside a number of other plans.

A draft version of the new policy framework, which is to "support economic growth while addressing the environmental impacts of flying", will be published in spring 2012.

The idea for the railway line, which had already been discussed in the past, was proposed by London councillor Victoria Borwick, who is a member of the city administration's transport commission, according to UK newspaper The Financial Times.

Borwick was not immediately available for comment.

London's mayor, Boris Johnson, wrote in The Daily Telegraph today that the railway link is "certainly worth considering" because building a third runway would be "utter madness". However, he added that the combined use of the two airports would require an additional runway in Gatwick.

British Airways says that the high-speed rail line would do "absolutely nothing to address the ever more pressing issue of the south east's need to have more airport capacity".

The Board of Airline Representatives in the UK (BAR UK) echoed this view by saying that the rail link would not create a "viable hub" as flight connecting times would not be competitive with other airports.

"If airlines and airports believed a rail link could work it would have had their support years ago," said Mike Carrivick, BAR UK chief executive.

Source: Air Transport Intelligence news