The Rs 23,136-crore, 33.5-km-long Line 3 connects Colaba in the southern tip of the island city with Bandra-Seepz in the north via the international airport and is the biggest infrastructure project that the city has ever seen.
Also, on completion by 2022, the Line 3 will be the fifth largest underground metro in the world.
"We are hopeful of opening the financial bids for rolling stock for the Line 3 by the end of August. We've already received good pre-qualification bids from as many as six domestic and global consortia," said MMRC managing director Ashwini Bhide.
The consortia are Alstom Transport India-Alstom Transport France; CRRC Nanjing-CRRC Changchun-CRRC International Corp of China, Kawasaki Heavy Industries of Japan; CAF of Spain, Hitachi from Japan, and a consortium of Bhel-Mitsubishi Corp, she said.
Of these, CAF, Hitachi and Mitsubishi are independent bids, said Ms Bhide.
After evaluating these bids, MMRC will invite financial tenders from shortlisted companies in consultation with the Japan International Cooperation Agency, which is funding 57.2 per cent of the project cost at a soft loan for 30 years.
Ms Bhide said the winning consortium will have to manufacture 75 per cent of coaches locally though not necessarily in Maharashtra itself.
The state-of-the-art eight-coach cars will be driver-less trains, said MMRC director (projects) SK Gupta. MMRC will procure 31 cars of eight coaches each, or 248 coaches in total, in the first phase. Each car will be 22.6-metre-long and 3.2-metre-wide with four gates per car.
The contract will include design, manufacture, supply, installation, testing and commissioning of the rolling stock.
Describing the Line 3 as the biggest infrastructure project in the megapolis, Ms Bhide said the the biggest such venture in Mumbai so far, the Bandra-Worli Sea Link - has cost only Rs 1,600 crore, while the Line 3 is 14 times larger.
The Line 3, on completion by FY22, will reduce daily fuel demand by around 4 lakh liters, or close to 10,000 tonne of green house gas emissions per year, as it will take at least 4.5 lakh vehicles off road daily.
The city is building five more metro lines of which civil work on the Line 2A and Line 7 have already started. These six line new metro lines will cost close to Rs 1 trillion and are being implemented by the nodal development agency MMRDA.
Executive director (planning) at MMRC R Ramana said the Line 3 will need 17 tunnel boring machines (TBMs) which will arrive by end-August and the tunnelling will start from October from the proposed Naya Nagar station in the Dharavi slum area in central Mumbai.
Mr Gupta said that Line 3, which will have just one of the 27 stations on-ground, needs 78.67 hectares land, of which only 3.45 hectares are private land.
Of the total government land of 74.22 hectares, 64 hectares have already been acquired and of this 30 hectares are at the Arey Colony where the metro will have the casting yard and depot. Out of the 30, 5 hectares will be untouched and will remain a natural green cover, Ms Bhide said.
She ruled out building commercial space at the stations, saying it isn't commercially viable to build large space at the stations, though each of them may have some urgent utilities like ATM and snack bars.
"Out of the total project cost of Rs 23,136 crore, over Rs 18,000 crore are only for tunnelling and stations. Effectively, cost works out to be Rs 2 lakh per sq ft and we cannot charge so much from a tenant. Each station will have a built up space of 240-250 sq meter space only," she said.
Asked whether the project is on time despite many legal hassles it had to face, Bhide said, "very much".
"No there is no uncertainty over the project. The metro will be a reality on time, and that is by 2022," she concluded.