The plans for a mass transit network follow a Paris-funded feasibility study by French engineering consultant BCEOM, which identified areas for four lines and assessed the viability of different types of system including an underground heavy rail system, an overhead light railway and a tramway system.

The first route suggested for development is a 13-kilometre line from Mezzeh, in west Damascus, to Qaboun in the east. A second corridor from Barzeh in the north to Mukhayyan in the south has also been identified as a priority.

At around $200 million, a tramway system is the cheapest option, although its technical characteristics are less attractive than a light or heavy rail system. A tramway would have lower capacity than a metro system and would have to be supplemented by other rail and bus services. However, the inclusion of cut-and-cover tunnels in key areas could limit the disruption of a system which is entirely at ground level.

An underground heavy rail system and overhead light rail system are also being considered. These provide the greatest expansion potential, better quality of service and minimal environmental impact. However, they are described as 'several orders of magnitude more expensive than the tramway alternative' by one project source, who says the cost of a subway could be as high as $1,000 million. Another risk is the uncertainty of tunnelling under one of the world's most historic cities. Tunnelling on the first line of the Cairo Metro was severely delayed to preserve archaeological sites.

'The problem is the economic viability,' says a project source. 'There are three or four scenarios. A heavy subway that could cost around a $1,000 million, a light tramway system would cost around $200 million, while a light rail system would cost between $400 million and $600 million.'

If the EIB determines that there is some potential in the project it will issue a tender for a consultant to carry out a technical evaluation.