Mumbai Metro Aqua Line (3): Connecting the unconnected

One of them, Line 3, to be called the Aqua Line, between Colaba and Aarey (popularly called Colaba-Bandra-SEEPZ line) is over 90 percent complete. Trials are already on going in the Aarey to Bandra Kurla Complex (BKC) segment, which is expected to start in early 2024, with the entire line to be opened by end 2024.

This is a 33.5 km underground line with 27 stations (26 of them underground, with the northern terminal Aarey at-grade). This line connects critical points of Mumbai, including the older and new central business districts, three railway terminals (Churchgate, Mumbai Central and CSMT) and two airport terminals (T1 and T2).

It will also connect the high-speed railway terminal stations at BKC. This line is special in the connectivity that it offers, so much so that it is positioned as ‘connecting the unconnected.’

Challenges Overcome

Apart from connectivity, there are many positives pertaining to how this line addressed various challenges. This project adopted the New Austrian Tunnelling Method (NATM) over the tunnel boring machine (TBM) in some sections, even though it would be at a slower pace. NATM enables better protection of the tunnel, even during construction. This was important to protect the heritage and religious structures that were close to the metro alignment.

Residents of buildings that were affected during the construction were shifted temporarily to hotels. Due to the underground alignment, the impact on traffic during construction was limited to the station areas. Even in this case, wherever possible, non-road areas such as open grounds were used to keep the overground construction equipment.

In other instances, road lanes were laid out on steel structures to enable traffic flow while work could be carried out below. Despite this, some roads had to be restricted for traffic, like the one at Churchgate station.

The rehabilitation of about 2,800 project-affected families was done in a consultative manner, with the involvement of the local government and the Slum Rehabilitation Authority. Most were comfortable with what had been offered. For legal title holders (about 25 percent of those affected), the rehabilitation was through new construction in the same location.

Plans for this line were first made in 2011, initially from Colaba to BKC, but later extended to connect the airport and SEEPZ. The detailed project report estimated a cost of Rs 23,000 crore. Approval was received in 2012, with a deadline of 2016.

After financial closure, with 57.2 percent of the funds from Japan International Cooperation Agency, the ground-breaking was done in August 2014, starting with the Aarey depot at the northern end of the line. The actual work started in 2016, when the cost was revised to Rs 37,200 crore, with a deadline of 2021. The project was executed in seven contract packages. COVID and controversies delayed it further, to an expected 2024.

Aarey Controversy

One of the controversial aspects of the project was the location of the depot at the northern end, occupying 34 of 1,300 hectares of Aarey Colony. This is a green area, often referred to as the ‘lungs’ of Mumbai.  Due to the controversies, the Maharashtra government decided to stop work in 2020 and consider alternative locations including Kanjur Marg.

This would have significant operational implications, including a possible alignment change of about 9 km or joining with another line that would pass near Kanjur Marg. There was also confusion on the availability of alternative land, which was under dispute.

When the NDA government came back to Maharashtra in 2022, it was decided to retain Aarey. The Supreme Court also allowed the last tranche of trees to be cut, imposing a fine, as late as April 2023. There are various estimates of the number of trees that were cut for the depot.

MMRCL has put out information on the significantly higher carbon saved due to the metro over what is lost due to the trees. Compensatory afforestation (more than required by regulation) has been ensured by MMRCL, including in the national park adjoining Aarey Colony. However, the debate on the impact of infrastructure projects using eco-sensitive land on biodiversity is still open.

Future Challenges

The line will be operated by the Delhi Metro Rail Corporation (DMRC), which won the contract in April 2023. However, as the line gears up for opening, there are challenges ahead.

The capacity of this line is 72,000 peak hour per direction traffic (PHPDT) served by eight-coach trains running every two minutes. This translates to 2,400 passengers per train.

In contrast, the Mumbai suburban services handle up to 90,000 passengers (at a dense crush load of 4,500 passengers per train, most of which are 12-coach and some 15-coach) per corridor during peak hour in Central and South Mumbai. There are five such corridors, with the total actual PHPDT about 300,000 passengers.

The impact of this metro line could be about 16 percent since the actual operating headway would be 3 minutes. For a real easing of the traffic, it will be important for the other metro lines to become operational, notwithstanding the shift of commercial activities northward in Mumbai.

A significant challenge is integration with other modes, at Churchgate, CSMT, Mumbai Central, other suburban stations, other metro stations, and airport terminals. Integration needs to be more streamlined for customers.

Dedicated passages with escalators and travelators are a must. The connection at Churchgate requires walking along roads and using existing under-bridges. A 350-metre tunnel is proposed between the metro station and the western end of CSMT station, where suburban trains come.

Long-distance trains can be on platforms that are a further kilometre away. The whole connectivity streamlining needs coordination with the Indian Railways, to be effective. Similar attention is required at Mumbai Central and the airport terminals, where the connecting distances are a little better.

Additional construction for streamlined pedestrian movement at stations, intermediate passenger transport and buses need continuous monitoring and execution. There could be opportunities for direct connections to specific buildings. Standardised and easy-to-spot signages to guide traffic would be essential.

There is a consideration of extending the line towards the south to Navy Nagar. There could be similar demands towards the north or even in between to connect to an important facility.

The focus of metro operations hence cannot be restricted to within the metro system but should be on enabling a ‘supply chain’ focus on customer flows beyond the metro.

And finally, being an underground system, safety and disaster management would need a heightened level of preparedness (continuous learning from others’ experiences and consequent training and drills), monitoring and alertness. Be it an accident, fire, flooding, or any other disaster…

Continuous coordination between multiple organisations (MMRCL, DMRC, MMRDA, Maha Metro, BMC, Indian Railways: Western and Central, MRVCL, BEST, NDRF, SDRF…) would be essential. This should happen in a positive, ‘for the customer’ spirit, if we truly want to connect the unconnected.

G Raghuram is Professor Emeritus, Gujarat Maritime University and Chanakya University, and Advisor, The Infravision Foundation. Views are personal, and do not represent the stance of this publication.