A 20 km metro line from Colaba to Bandra was announced in January 2004, as part of a master plan unveiled by the Mumbai Metropolitan Region Development Authority (MMRDA). The plan encompassed a total of 146 kilometres (91 mi) of track, of which 32 kilometres (20 mi) was proposed to be underground. The MMRDA unveiled plans for an extended Colaba-Bandra-SEEPZ metro line in 2011. According to its earlier plans, a 20-km metro line from Colaba to Bandra was to be constructed, running underground for 10 kilometres (6.2 mi) from Colaba to Mahalaxmi, and then on an elevated track from Mahalaxmi to Bandra. The MMRDA decided to extend the line to the Chatrapati Shivaji International Airport to increase ridership. The 33.5-kilometre (20.8 mi) Colaba-Bandra-SEEPZ line was estimated to cost ₹21,000 crore (US$3.1 billion), have 27 stations, and would be the city's first fully underground metro line. at Nariman Point, BKC, MIDC, SEEPZ, and elsewhere. According to the MMRDA, an underground metro will minimise land acquisition and disturbance to traffic during construction compared to an elevated metro.
The Mumbai Metro Rail Corporation Ltd (MMRC), registered under provisions of Company Act, 1956, was constituted as a fully owned company of the MMRDA on 30 April 2008, as per state government directives. On 27 February 2012, the Central Government gave in-principle approval to the plan for Line 3. In April 2012, the MMRDA announced plans to grant the MMRC increased management autonomy, in an effort to enhance the project's operational efficiency.
In early 2012, the MMRDA conducted talks with officials at Chhatrapati Shivaji International Airport (CSIA) to finance or construct the line's three stations at the airport and GVK SkyCity, a proposed nearby commercial development. Mumbai International Airport Limited (MIAL) agreed to bear the cost of constructing the three stations, which is expected to total ₹777 crore. According to MIAL's CEO, R.K. Jain, MIAL is willing to contribute to the metro's construction because of the potential increase in passenger convenience. MIAL estimated the cost of developing the metro lines in the airport as ₹518 crore.
In August 2012, the Urban Development Ministry rejected the Planning Commission's proposal to implement Line 3 in a public-private partnership (PPP) mode, having found the mode unsatisfactory for the Delhi Airport Metro Express. The ministry instead proposed a funding pattern with a ratio of 20:80 between the Centre and the State. Of the State equity, 45% was proposed to be through a loan from the Japan International Cooperation Agency (JICA).
JICA will provide financial assistance in the form of a soft loan amounting to ₹13,235 crore (US$2.0 billion) for the ₹23,136 crore (US$3.4 billion) project. JICA will fund 57.2% of the equity. The soft loan has an interest rate of 1.44%. The other finance will come from the central and state equity of 10.4% each, sub-debt by the central government (4.4%), sub-debt by the state (7%), property development and impact fee (4.3%), stakeholder contribution from the Mumbai International Airport Ltd. (3.4%) and MMRDA grant/aside funding (2.9%).
The Union Cabinet granted clearance to Line 3 on 27 June 2013. The Cabinet also decide to convert Mumbai Metro Rail Corporation (MMRC), the existing state-level special purpose vehicle formed to implement metro projects, into a joint venture company of the state and central governments with equity participation. The MMRC's board consists of five members each from state and central governments. The MMRDA presented their metro line plan to the Brihanmumbai Municipal Corporation on 13 February 2014.
Line 3 was approved by the state cabinet on 26 February 2014. Line 3 is being implemented through the engineering, procurement and construction (EPC) model. The foundation stone for the project was laid by Chief Minister Prithviraj Chavan in a bhoomi pujan ceremony at Andheri on 26 August 2014, in the presence of Union Urban Development minister Venkaiah Naidu. The move was described by the media as a cosmetic gesture, as the developers of the project had not yet been decided and actual construction was expected to begin only by December 2014. The date of the ceremony was a few days before the code of conduct for the 2014 State Assembly elections would come into force, which would prohibit the ruling Congress-NCP government from politicising the ceremony. Some citizens protested against the State government at the ground breaking site. They protested the slow implementation and cost escalation of the Mumbai Metro project. Tendering for the project was delayed by the re-organization of the MMRC from a wholly owned entity of the State Government, to a joint venture between the Union and State Governments. Although the State Government received the file for reconstituting the company in October 2013, it gave approval only in July 2014.
In December 2014, the MMRC appointed a consortium led by Hong Kong-based AECOM Asia, in a joint venture with Padeco, Japan, LBG Inc. USA and Egis Rail, France as the general consultants for the implementation of the Line 3 project. The agreement between the two parties was signed on 26 May 2015. On 6 July 2015, the MMRC unveiled a new logo, designed by Design Orb, for Line 3. UPS Madan, Director, MMRC and Metropolitan Commissioner, MMRDA, explained, "The earlier logo was designed with an elevated Metro-3 corridor in mind as was planned originally. The new logo presents the organisation more appropriately as its more relevant, fresh and robust". He also noted that the earlier logo had been designed while the MMRC was owned by the State Government, while it was now a joint venture between the State and the Centre.
The MMRC will have to rehabilitate 2,807 families for the project. Most of the families were relocated to Kurla and Chakala. The MMRC also provided free hotel accommodation to people residing in old, dilapidated buildings along the metro corridor that were in danger of collapsing during tunneling work. The majority of such buildings were located in the Girgaum-Kalbadevi belt in South Mumbai.
The MMRC called for pre-qualification bids in September 2013. Bidders for the work on tunnels and stations were to submit their bids by 30 October 2013. On 31 January 2014, the bid document was modified and the annual turnover requirement was reduced to "average annual construction turnover of not less than USD 175 million defined as billing for civil infrastructure work completed or in progress over the last five years ending on March 2013". Sanjay Sethi, managing director of MMRC, stated, "The annual turnover requirement must have been set with the idea of attracting specific companies to the project. However, the Japan International Cooperation Agency (JICA) felt that consortia or joint ventures are a combination of management contractors and construction contractors. In all Metro projects, the annual turnover is the starting point for bidding based on which we should not restrict applications. The issue was also raised by several potential bidders." The last date for the submission of pre-qualification bids was extended to 10 March 2014. Fourteen pre-qualification bids were received for the design and construction of underground stations and tunnels for Line 3. The 14 bidders were: Afcon-KMB, CEC-ITD Cementation India-TPL, CTCEC-Pan India Infrastructures Pvt Ltd, Dogus-Soma Constructions, IL&FS-CR256 (China Railway), JKumar-CRTG, Larsen & Toubro-STEC, Mosmetrostory-Hindustan Construction Company, OHL-SK Engineering & Construction, Pratibha-GDYT Consortium, Sacyr-CMC-Essar, Salin Impreglio-Gammon, Strabag-AG-Patel Engineering and Unity Infrastructure-IVRCL-CTG. Tenders to construct the car depot at Aarey colony were floated by the MMRC in July 2014.
Of the 14 consortia that submitted pre-qualification bids, 9 were shortlisted in September 2014. According to Sanjay Sethi, managing director of MMRC, "We have finalised the list of companies eligible for bidding after getting an approval from the Japan International Cooperation Agency (JICA), which is providing more than 50 per cent of funds for the project. The companies that were declared ineligible mostly fell short in technical experience. The tender for construction of Line 3 received was split into seven packages, each consisting of a 4-5 km long twin tunnel. The tender floated by the MMRC received 31 bids from 9 consortiums. The first four packages received 4 bids each, while the next three packages received 5, 7 and 3 bids respectively. The 9 consortia were AFCONS Infrastructure Ltd. - Kyivmetrobud, Continental Engineering Corporation - ITD Cementation India Ltd - Tata Projects Ltd, DOGUS - SOMA, IL&FS Engineering and Construction Company Ltd - China Railway 25th Bureau Group Co.Ltd, J.Kumar Infraprojects Ltd - China Railway No.3 Engineering Group Co. Ltd, Larsen & Toubro Ltd/Shanghai Tunnel Engineering Co. Ltd, OSJC Moscow Metrostroy - Hindustan Construction Co.Ltd, Pratibha Industries Ltd - Guandong Yuantian Engineering Co., and Unity Infraprojects Ltd - IVRCL Ltd - China Railway Tunnel Group Co. Ltd. Contracts for all seven packages were awarded by August 2016.
In January 2017, the MMRC floated tenders for the construction of the metro car depot at Aarey Colony.
The project will affect 5,012 trees, of which 1,331 will be cut and the remaining 3,681 will re-planted in other parts of the city. Per the terms of the contracts awarded to various consortia, they are in-charge of transplanting affected trees and planting new trees to make up for those cut down. The contract requires consortia to plant three times the number of trees cut down for the project, and maintain them for a period of at least 3 years. The consortium of Tata Projects, ITD Cementation and CEC Taiwan, which won the contract to construct the package 4, pledged to construct 4 times more trees than it was required to plant under the contract. The work on package 4, the section between Siddhivinayak Temple and Mahim, required the felling of 150 trees. The consortium pledged that it would plant 2,000 trees instead of the required 450.
On 9 February 2017, the Bombay High Court issued an interim order prohibiting the MMRDA from cutting trees for the project. The Court was hearing two PILs filed by Mina Verma and Pravin Jehangir. Verma's PIL concerned tree felling in Churchgate, Colaba and Cuffe Parade, and Jehangir challenged the use of public lands for construction of the line. On 10 March 2017, the Court ordered the MMRC to furnish documents proving that it had received necessary clearance from the MoEF to construct the proposed stations of Hutatma Chowk, Churchgate and Cuffe Parade, or documents to prove that no clearances were required. The order was in response to the petitioner's claim that the MoEF had rejected the MMRC's request to construct the 3 stations. The MMRC responded that no clearance was required to construct the stations. On 16 March, the Court issued a notice to the MoEF asking it to clarify whether it had granted clearance to the MMRC to construct nine stations. The petitioner had pointed out that all nine stations fell under the Coastal Regulatory Zones II and III.
On 28 February 2017, the MMRC announced that it would donate 25,000 saplings to housing societies, hospitals, and schools located along the metro line. The MMRC stated that the donation was in addition to compulsory tree plantation required by MCGM regulations. In January 2017, the MMRC hired arborist Simon Leong from Singapore to serve as a tree consultant on the project. Leong will provide his services for a six month period at a rate of $33,000 per month.
MMRC Director Ashwini Bhide criticized the controversy over the tree felling required for the project saying that infrastructure could not be built without cutting down trees. Bhide stated that the metro had been designed to minimize the loss of trees, and that 3 times more trees would be planted to make up for the loss. Bhide further explained that the 5,000 trees proposed to be cut for Metro 3 would reduce carbon dioxide by 6,100 kg, while reduction in vehicle usage as a result of Metro 3 would reduce carbon emissions by an estimated 9.9 million kg. Bhide also stated that the MMRC had considered considered building the depot at Kalina and Kanjurmarg but decided against it due to lack of availability of land and potential legal disputes involving land in the area.
In 2015, the state government announced plans to construct the metro depot, where metro coaches will be parked, on an 81 acre plot of land in Aarey Colony. Authorities also intended to construct a labour camp for construction workers and a centralised operation control centre for the entire Mumbai Metro network at Aarey Colony. The construction would require the felling of more than 2,000 trees in the area. Environmental groups Vanashakti and Aarey Conservation Group (ACG) filed a petition with the National Green Tribunal (NGT) in January 2015 requesting that the Aarey Colony be protected as a no-development zone. On 5 December 2016, the Union Environment Ministry issued a notification declaring the area up to 4 km from the boundary of the Sanjay Gandhi National Park to be an eco-sensitive zone. The notification excluded 165 hectares of land in Aarey, in order to permit the construction of Line 3. However, the notification declared that the exclusion was sub-ordinate to any orders from the judiciary or the NGT.
The NGT's Pune bench passed an order temporarily staying all construction activities in Aarey on 19 December 2016. On 5 January 2017, the NGT granted an exemption permitting the MMRC to construct a casting yard on a 3-hectare plot of land owned by the State Government in Aarey. A tribunal bench ordered the forest department to provide a detailed map of Aarey Colony, and to declare whether any portion of the region had been identified as forests. In 1997, as part of a Supreme Court directive, State Governments had prepared a detailed map of urban forest cover. The forest department failed to provide the details at the next hearing, and on 17 February 2017, the NGT extended its stay on all construction activities up to 17 March 2017.
Due to the issues surrounding the land at Aarey, Larsen & Toubro and Shanghai Tunnel Engineering Co., the consortium that was awarded the seventh package to carry out construction on the MIDC-Aarey Depot section of the line, exited the contract. The MMRC stated that the appointment of a new contractor would escalate the project cost by an addition ₹10 crore (US$1.5 million). The Court stated that it would determine if the cutting of nearly 5,000 trees for the project was necessary.
On 18 February 2017, Fadnavis directed the MMRDA to consider constructing the depot at Kanjurmarg or Kalina. A few weeks later, MMRC officials stated that the proposed depot could not be built at Mumbai University land in Kalina because the available area was too small. The MMRC insisted that the depot should be built at Aarey, but proposed a new design which would allow the depot to be construct on 25 hectares of land as compared to the 33 hectares required by the old design. The new design will reduce the number of trees to be cut by 1,000.
In March 2017, E. Sreedharan wrote to Chief Minister Fadnavis requesting him to ensure clearance for proposed metro depot at Aarey. Sreedharan wrote, "Metro projects are environmentally most friendly and setting up a carshed in Aarey is not going to be a threat either to the government or to the eco system. The main objection would be against cutting of trees, for which compensatory afforestation on a liberal scale can be insisted upon."
Two 5.2 metre diameter twin tunnels of 33.5 km each will be dug at a depth of 20-25 metres. Seventeen tunnel boring machines (TBMs), each weighing around 1400 tonnes and costing ₹120 crore (US$18 million), will be used to dig the tunnels. The TBMs will be lowered through shafts or pits using a specialized crane. Pre-cast segments will be put on the tunnels' diameter to prevent cave ins, after the TBMs bore 1.2 metres. Tunnels will have to be dug through a mix of soil and basalt rock, and is expected to be difficult. TBMs can dig at an average rate of 8 metres per day through rock, and at a rate of 14 metres per day through soil. After TBMs bore through section, the metro tunnel will be lined with pre-cast concrete rings to strengthen the tunnels. Boring and placing rings occurs sequentially. For the entire Metro 3 corridor, around 40,000 concrete rings were cast in 65 moulds. Casting of the rings took place at six casting yards - four in Wadala, one each at Darga, and on the Jogeshwari-Vikhroli Link Road (JVLR). The first concrete ring was fabricated at a Wadala casting yard on 7 March 2017.
Underground construction will be carried out at an average depth of 15 to 25 meters. The Hutatma Chowk, Kalbadevi, Girgaum, Grant Road, Shitladevi, Santacruz and Marol Naka stations will be constructed by the New Austrian Tunnelling method, while the other 20 stations will be constructed by the cut-and-cover method. In the latter method, the ground is dug, the entire station constructed, and finally the top is covered. Underground utilities will have to be shifted to construct the line, as it is completely underground.
The original deadline for the project was 2016, but it is currently expected to be completed in 2021. Construction work on the project began on 21 October 2016. The work has faced delays due to several legal disputes. In March 2017, MMRC officials stated that they were unable to proceed with full scale construction activites due to legal issues, and that contractors were currently carrying out other activities such as shifting utilities, geo-technical surveys, and fabricating pre-cast segments. Officials further added that if construction did not begin within one month, the project cost would escalate at the rate ₹4 crore (US$590,000) per day and would result in higher passenger fares.
Tunneling work on the corridor is expected to begin by October 2017. The first phase of the line between Aarey and BKC is expected to open in 2020, and the remaining section will open in 2021.
There will be 27 stations on Line 3. Aarey Depot is at grade, while the other 26 stations are underground. Stations will be equipped with platform screen doors.
Passenger interchange facilities will be provided at Chhatrapati Shivaji Terminus (Central Line); Churchgate, Mumbai Central and Mahalaxmi (Western Line), Marol Naka (Metro Line 1), Bandra-Kurla Complex (Metro Line 2) and Mahalaxmi (Mumbai Monorail).
The car yard, where metro coaches will be parked, will be built opposite SEEPZ on an 81 acre plot in Aarey Colony.
In March 2017, the MMRC floated tenders for multiple works on Metro 3 including the traction system, power supply, tunnel ventilation, signalling, train control, platform screen doors and telecommunication system. The contracts include the manufacturing, supply and installation of these systems.
The MMRC invited bids to supply rolling stock for Metro 3 in December 2015. 31 trains with 8 coaches each will ply on the line. The process of procuring rolling stock was delayed due to a disagreement between the Central Government and JICA. The Centre wanted 75% of the total rolling stock procured for the line to be manufactured in India even if the contract was awarded to a foreign company. However, JICA wanted the bid for rolling stock to have no restrictions.
Metro 3 will be driverless. The line has an automation level of grade 4. However, the line will employ drivers during its first year in operation. Trains on the line will also utilize a time-interval system which allows them to maintain the minimum possible distance required for safety between each other. As all trains are connected with the operation control centre, every train is aware of the speed and distance of all other trains.
Metro 3 utilizes a communications-based train control (CBTC) signalling system. There are no signals on the line, and speed and distance between the trains is monitored by onboard computers that are connected with a central computer in the operations control centre.
MMRDA joint project director Dilip Kawathkar stated that AC power was chosen for Line 3 "after a proper study by a team of experts" which found that the AC model was "a better option". Experts believe that the decision to use AC escalated the project cost by 15%, since more digging is required for the rail to work on AC.
Despite providing connectivity to Mumbai's airport, passengers on Metro 3 will not be permitted to carry their check-in luggage onboard trains. Only hand/cabin baggage will be allowed. MMRC officials stated that Metro 3 was not an "Airport Express line", but a regular city metro corridor. Officials explained that providing luggage check-in would require additional dwell time at the Airport metro station, which would increase the overall headway of the line, and disrupt services for other passengers.
Metro 3 will utilize an open loop automated fare collection system. Passengers will be able to pay for travel using contactless pre-paid and post-paid smart cards issued by partnering banks. Only RuPay debit and credit cards are accepted on Metro 3.