The Roads and Transport Authority (RTA) hopes to launch Dubai Metro's Green Line by June 2010 – but all other proposed lines will be delayed until it is able to enter into public-private partnerships.

A Blue Line is proposed along a 47km route along Emirates Road, linking Dubai International Airport and Al Maktoum International Airport in Jebel Ali.

And a 49km Purple Line to run parallel to Al Khail Road will provide an express service between the two airports in 40 minutes, including stopping time.

Construction of the Blue and Purple lines has, however, been delayed as the RTA looks at ways to finance the multi-billion-dirham projects.

The Green Line, at 22.5km, will connect 18 stations in Deira and Bur Dubai and will have an initial capacity of 6,395 passengers per hour. Once completed, it will make Dubai Metro the world's longest automated metro network, overtaking the Vancouver SkyTrain in Canada.

"I hope the Green Line is completed by June 2010 and [God willing] it will be," said Chairman and Executive Director Mattar Al Tayer.

"All other colours [Blue and Purple] have been delayed. We are now thinking of entering into public-private partnerships for any projects of such magnitude. This is because of the financial situation," he said.

The additional lines were announced in June 2007 and the designs were completed in February this year, with construction costs estimated at $2.73 billion. Three of the Purple Line's eight stations would offer airport check-in facilities and the trains would travel at an average speed of 100kph, with a top speed of 160kph.

In addition to these lines, the RTA also announced plans for 268km of light rail tracks to act as a feeder system for the Metro. The fate of this entire network – which would reportedly be divided into Yellow, Orange, Magenta and Black lines – is now dependent on an economic recovery and private investment.