Consultants will have until year-end to submit offers, with an award expected in mid-January and work beginning on 1 February. The six bidders are Italfer and Lotti & Associati, both of Italy, Spain's SENER Ingenieria y Sistemas with the UK's Mott MacDonald, a French team of BCEOM and Semaly, France's Systra with Lebanon's Khatib & Alami, Germany's DE-Consult with the UK's WSP and a Turkish company identified as Optima.

The 18-month study will centre on the construction of the 14.8-kilometre green line from the ministries district in Mezzeh to Qaboun. The line will have 22 stations and cost an estimated $500 million-1,000 million. The consultancy contract also covers financing models for the scheme.

The successful consultant will carry out the study to integrate three other lines creating a 52-kilometre network across the city. The project aims to alleviate chronic traffic congestion and meet population growth, expected to increase to 6 million in 2020 from 1.8 million. BCEOM carried out the feasibility study.