By Julia Wheeler
BBC News, Dubai
200 million passenger journeys are anticipated on the metro each year
The first urban train network in the Gulf is due to open on Wednesday in Dubai.
The Dubai Metro will eventually become the world's longest driverless train system with more than 70km (43 miles) of track.
It cost almost twice the original estimate and opens at a time when Dubai is suffering from economic troubles due to the global recession.
The metro's challenge will be to persuade car drivers to get on board.
The train system was conceived when traffic on the eight-lane Sheikh Zayed Highway, along which much of its track now runs, was bumper to bumper, morning and evening.
It was planned when the economy was booming and the population burgeoning.
But, the opening of the first stations along 52km (32 miles) of the track comes when many of Dubai's congestion problems have already been solved - by the global economic crisis.
With fewer tourists visiting and more migrant workers leaving, there is already less traffic on the roads.
One of the main challenges is to persuade motorists, who are used to subsidised fuel and the privacy of air conditioned comfort, to swap their cars for a mass transit system.
With daytime summer temperatures regularly exceeding 40C, this is not straightforward.
The authorities have built futuristic stations - and introduced reasonable fares, women-only carriages and luxury leather seats for those who would like to pay for them.
They say they anticipate 200 million passenger journeys on the metro each year.
Many residents believe the metro is a positive social and environmental addition in a city which wants to be recognised for modern thinking.
Just when the authorities will see the economic payback on their $7.6bn investment is more difficult to predict.