The deal to build a fully automated metro was signed by Dubai Municipality, which is leading the project, and a representative of the consortium of four companies.
The driverless metro will consist of two lines covering the main locations across Dubai and will feature elevated and underground sections. Construction is scheduled to start in July.
The first phase of the project, which comprises a 52.1km line between the city's airport and the industrial and port free zone of Jabal Ali, is expected to be inaugurated in September 2009.
The full 69.7km long rail link across Dubai is to be completed in less than five years, said the municipality's Director-General Qasim Sultan.
Mitsubishi leads the Dubai Rapid Link (DURL), which brings together the Japanese Obayashi and Kajima companies and the Turkish Yapi Merkezi. The group beat four other contesting consortia for the lucrative contract.
Road use is expected to grow
rapidly in Dubai
DURL's bid of 12.45 billion dirhams came far ahead of the nearest offer by Dubai Star, including France's Alstom and Germany's Bilfinger Berger, which stood at 18.26 billion dirhams ($4.98 billion).
Salsabeel, which grouped Germany's Siemens and the Saudi Bin Laden Group, followed suit with 18.84 billion dirhams, while Metro One, teaming six firms led by Canada's Bombardier, came last with 19.29 billion dirhams.
"We found all offers were acceptable from a technical point of view. The difference was that some consortia were better than their counterparts in certain aesthetic aspects ... There was (also) a substantial difference in the rates quoted by the consortia," said general coordinator of the project Nasir Said.
DURL also clinched a 1.88billion dirham contract to carry out maintenance of the project for 15 years.
"The difference was that some consortia were better than their counterparts in certain aesthetic aspects..."
Dubai, which is aiming to become the region's prime business and leisure destination, has an estimated annual population growth of 6%, according to official figures.
More than a million cars are on the roads of the emirate, home to 1.2 million people - 957,000 of them foreigners.
Buses and ''abrat'' (boats) in Dubai currently carry 90 million and 15 million passengers a year, respectively.
Many of the urban areas in Dubai, one of seven city states that make up the United Arab Emirates, now experience severe traffic congestion, and the average number of daily road trips is expected to increase from 3.1 million to 13.1 million by 2020.