Thane-Borivali Tunnel: A Shortcut Through Mumbai's Green Heart

But its impact on Mumbai’s only national park will be known only after the project is well on its way to completion, contrary to a condition laid down by the National Board of Wildlife (NBWL) while granting permission for the project.

As planned, the project will run under the Sanjay Gandhi National Park (SGNP) and is aimed at providing east-west connectivity, reducing congestion on Ghodbunder Road, a major city connector, and is supposed to reduce travel from Thane city to Borivali in western Mumbai by 12 km.

Megha Engineering and Infrastructure Ltd (MEIL), the second largest donor through the now-scrapped electoral bonds scheme, has won the contract.

During the bidding process, Megha Engineering was the only firm whose bid was found eligible. Larsen & Toubro had filed pleas in the Bombay High Court against the decision, but the pleas were dismissed.

MEIL was one of India’s largest donors to the electoral bonds scheme, purchasing bonds worth around Rs 966 crore. These bonds were encashed by major political parties including Congress and the Bharatiya Janata Party. In fact, MEIL bought bonds worth Rs 140 crore just a month before winning the bid for the Thane-Borivali project.

Former cabinet minister of Maharashtra Jitendra Awhad had questioned the contract allotment to MEIL after the bond data became public, saying that the money was spent [in bonds] to secure such contracts.

Gestation of the project

The alignment of the project (in red) starting from Borivali to the left and Thane to the right

Credit: Mumbai Metropolitan Region Development Authority (MMRDA)

The tunnel project had been on paper for years, until it was given clearance by the state wildlife board in October 2023. Earlier this year, the NBWL greenlit the project too subject to a list of conditions, one of them being that “A cumulative study on the effect of construction of underground tunnel [on] the ecological, geological, hydrological and seismological aspects of the Sanjay Gandhi National Park (SGNP) from WII needs to be undertaken… before commencement of the project. Accordingly, the necessary precautions and safety measures… shall be incorporated in the project.”

The Wildlife Institute of India, Dehradun or WII--an autonomous institute under the Union government--found the private studies carried out by executing agency Mumbai Metropolitan Region Development Authority (MMRDA) to be sufficient, and suggested that the impact of the tunnel on SGNP’s wildlife be assessed before, during and after the project.

Over the years, environmentalists have raised concerns over the proposed project and how it will affect the biodiversity, aquifers, ecology and other natural elements of SGNP. In the absence of an environment impact assessment, the study can bring to the fore crucial information on the same. However, the study will take at least two years to complete, whereas construction of the tunnel is slated to begin after the monsoon season, officials told us.

“It is ironic, because the National Board of Wildlife is chaired by the PM,” said environmentalist Debi Goenka, a trustee of the Conservation Action Trust.

“It would be ill-advised to go ahead with tunnelling under such an ecologically sensitive and water-sensitive zone without getting the studies done,” said environmentalist and former member of the state wildlife board Bittu Sehgal. “They had enough time, they have been thinking about this for eight years. What happens if in some form or the other, the aquifer is damaged and we start losing the water in the lakes? What if sea water starts coming in? I’m not saying that it will happen. I’m saying that without getting a proper independent geological and hydrological survey done, no work should be done.”

Since WII is only studying the impact on wildlife, it is not clear how the impact on geological, hydrological and seismological aspects will be gauged, if at all. IndiaSpend wrote to MMRDA asking for comment on whether it has taken permission from the Union government for changing the nature of the study, the missing elements of the study, and MMRDA’s responsibility in making sure all conditions are fulfilled. This story will be updated when we receive a response.

Why does all this matter?

Mumbai is one of the few cities in the world which has a national park within city limits. The park is spread over 104 sq km in north central Mumbai.

SGNP is home to Schedule-I species such as the leopard, jackal, striped hyena, rusty spotted cat, Indian grey mongoose, small Indian civet, sambar; reptile species such as crocodile, dhaman, Indian cobra and rock python.

The eastern and western suburbs of Mumbai and beyond are connected by connectors such as Jogeshwari Vikhroli Link Road (JVLR) and Ghodbunder Road. However, between those two--that is, a distance of around 20 km--there is no east-west connecting road due to the presence of the SGNP. Millions of Mumbaikars reside on either side of these suburbs and use these connectors or the Versova-Ghatkopar metro rail for east-west connectivity.

The proposal for a tunnel that goes under SGNP was first mooted by the Maharashtra State Road Development Corporation (MSRDC) in 2015. In 2020, the project was handed over to the Mumbai Metropolitan Region Development Authority (MMRDA), the agency which has become responsible for big ticket infrastructure projects such as Atal Setu (India’s longest sea bridge that connects Sewri in Mumbai with Nhava Sheva in Navi Mumbai) and several metro rail lines.

“The distance from Thane to Borivali via Ghodbunder is 23 km. It takes about one to 1.5 hours to cover [it] during peak hours and at least one hour at other times. The construction of a twin tube tunnel is proposed… so that the journey from Thane and Borivali will reduce by 12 km,” the MMRDA’s project description reads.

The project’s total length is 11.8 km, most of which passes under the national park. Each tunnel will have two lanes, and there will be cross connectors every 300 metres. The tunnels will be dug using four tunnel boring machines (TBMs), officials told IndiaSpend. At 13 metres diameter, these machines will be almost twice as big as the ones used for the Metro 3 project and the coastal road.

The work on their ‘portal’ or point of entry will be done after the monsoons, and the machines will actually start work early next year. They are supposed to go 25 metres underground, a depth which will not cause any harm to flora and fauna, MMRDA officials say. The project’s construction period is estimated at five years.

A visual representation of the Twin Tube Tunnel project

Credit: MMRDA

Another public agency, the Brihanmumbai Municipal Corporation (BMC), will also be digging a tunnel under the SGNP that was also launched in the same ceremony by the PM. The Goregaon-Mulund Link Road (GMLR) is also an east-west connector that was in the offing for many years and has now finally seen the light of day.

Speaking at the ground-breaking ceremony on July 13, PM Modi said, “GMLR is a great example of nature and progress. The Thane Borivali Twin Tunnel Project will reduce the distance between Thane and Borivali to a few minutes.”

Of the road’s 6.65 km length, 4.7 km will go under the SGNP as well, and environmentalists have had similar concerns for both projects. Stalin D., of the non-profit Vanshakti that works in environment conservation, believes that “to say there will be no impact is not correct”.

“When an earthquake happens, wildlife is the first to know,” Stalin said. “Maybe wildlife will get used to tunnel vibrations or noise in the future, but to say there won’t be an impact is not correct. Also, where will the tunnel’s ventilation shafts be? And will its service road or maintenance road also be underground?”

Based on a newspaper report raising concerns over infrastructure projects along/under the SGNP, the National Green Tribunal has taken suo motu cognisance of the matter and a hearing is expected later this year.

Concerns over the years

In 2018, while the Thane-Borivali project was still with MSRDC, the state wildlife board gave permission for survey and geotechnical investigation, but some members had suggested that “the three alternative sites must be included in the project proposal so that the possibility to avoid SGNP forest area can be explored”.

However, then chief minister Devendra Fadnavis told the Board that the proposal was only to conduct a survey and investigation, and thus the SBWL gave permission. Chief ministers also serve as chairpersons of the board.

Among the alternatives considered were an elevated road on Ghodbunder Road (which is also being constructed by MMRDA) or an elevated road along the same route going from within the SGNP (over the surface). But the latter was not considered because it “…passes through SGNP, may lead to significant disturbance to wildlife and use of forest land. On the other hand, tunnel construction would not require any forest land (or very minimum land), no displacement of people, no tree cutting etc.” The Thane-Borivali twin tube tunnel project requires 122 trees to be cut.

This proposal was cleared by the chief wildlife warden and passed by the Maharashtra SBWL in October 2023. The warden had listed a number of conditions in their approval that were retained by both SBWL and NBWL. These include: a cement concrete wall along the project where wildlife is liable to cross over, no blasting, norms of noise, air and water pollution to be strictly followed, and no damage or disturbance to the wildlife and its habitat in SGNP during execution and operational phases. The need for a WII study was also included.

The agenda of NBWL contained a factsheet on the project which had noted challenges before tunnel projects such as this one.

“Problems like ground vibrations, vibration induced noise and ground movement arise during underground constructions,” the factsheet had noted. “The environmental impacts and risks during the tunnel construction period generally include decrease in water exchange, habitat destruction, biological reduction, increase in suspended solids, water quality pollution, etc.”

After the NBWL approval came in, the Maharashtra government needed the Union environment ministry’s regional empowered committee (REC) to sign off on the project. It told the REC that the “subject foundation stone for the project is likely to be laid on 19.03.2024 and hence, requested the committee to issue conditional in principle approval”.

The REC approved the project in its February 8, 2024 meeting but despite that, why the foundation stone was not laid on March 19, before the Lok Sabha elections, as mentioned above is not known.

State wildlife board member Anish Andheria said that the tunnel plan is the lesser of the two evils.

“Initially the proposal was always for surface roads,” Andheria said. “The tunnel was suggested to at least not have something on the surface. When you have something on the surface, apart from obvious impacts, there are so many allied activities like movement of labourers, utilities like petrol pumps, which cause an impact [to the forest].”

The past as prologue

Just like the Thane-Borivali twin tube tunnel project, there were environmental concerns over the GMLR project as well, which is being executed at a cost of Rs 6,300 crore.

As a precautionary measure, both MMRDA and BMC had undertaken studies for their respective projects over the years. BMC had commissioned studies from Indian Institute of Technology, Bombay (IIT-B) to gauge the impact on aquifers/ groundwater and a study on the ecology from the Bombay Natural History Society (BNHS).

The REC in this case found lacunae in these studies. In 2022, it accorded in-principle approval to the project subject to the receipt of “a cumulative/holistic study on the effect of construction of one or more underground tunnels on the ecological, geological, hydrological and seismological aspects of the Sanjay Gandhi National Park from a reputed institution, keeping in view the ongoing activities of the Park.” The study was also supposed to conclude the carrying capacity of SGNP vis-a-vis underground tunnels. Even the 2023 approval of GMLR by the REC had mentioned that this holistic study needs to be done by a reputed institution “and implement the outcome measures before taking up any activity underneath SGNP”. The study is being done by Bombay Natural History Society (BNHS) but its status is not known. IndiaSpend wrote to BMC and BNHS with queries on this particular study, what its status is and when it will be completed. This story will be updated when we get a response.

For the Thane-Borivali project, MMRDA had commissioned an EIA and environment management plan, conducted a geotechnical investigation, hydro-geological studies and ecological sensitivity report from various private agencies. These reports were vetted by IIT Hyderabad, which concluded that the “project is required to mitigate the traffic congestion, and the proposed TBM [tunnel boring machines] for tunnel construction shall not have any impact on flora and fauna of the SGNP which is considered as lungs of the Mumbai City”.

These private studies were found sufficient by WII before the NBWL meeting on January 30 and it had already seemed to have concluded that the tunnel’s construction will have no impact on wildlife during or after.

“Wildlife Institute of India… shall suggest appropriate mitigation if needed. The other measures as proposed in the voluntary study are appropriate as of now,” it wrote to the Union environment ministry on January 19 this year.

After the NBWL directed it to conduct the holistic study in its January 30 meeting, WII will now be doing a comprehensive study to evaluate the habitat use and movement pattern of herbivores (chital and sambar), carnivores (leopard), burrowing mammals (rodents) and reptiles present within the limits of the national park.

“The learnings from the study will also help to develop mitigation plans for similar projects across the country. The study shall be conducted before, during and after the construction of the twin tunnel,” it said in a letter to MMRDA on February 7, 2024, contrary to the NBWL permission--which called for, as we said, the cumulative study from WII to be undertaken before commencement of the project.

“The point is, we all know that the MoEF clears several projects every month and every project has maybe 50-100 conditions attached to them, and there is no one to monitor their compliance,” said Goenka. “So, every time there is a violation, people who are impacted have to go to the court. These regulatory agencies aren’t doing anything, except making money.”

Conservationist and writer Prerna Singh Bindra, who was on the Standing Committee, NBWL between 2010-13, said that usually once the permission is received from the wildlife board, there is little attention paid to attached conditions.

“There is no real mechanism to monitor compliance –no will to report back to the NBWL, or the MoEFCC. But to me the bigger point is that such an impact study (in context of the study of twin tunnels] of a project -particularly one of this scale- needs to be done prior to being placed before the SC, NBWL, so that the decision to reject or approve is done on the basis of the study. I mean, what’s the point of all the destruction if, for instance, your study shows it is detrimental or fatal to the wildlife and the park? The mandate of the NBWL is to conserve wildlife and its habitat, and such decisions show disregard for our Protected Areas,” said Bindra

The wildlife study will involve collaring individual animals that are representative of their species. WII has recruited a team of six scientists for the project. The collars will have high resolution activity sensors which will record animals’ activity every second.

For the tiger census, the sensors record activity every five seconds but in this case, they will record activity every second, according to WII, in order to understand animals’ response to stimuli such as noise or vibrations. The study’s time period is two years, and it will cost around Rs 2.5 crore.

Pros and cons

Environmentalist Krishna Tiwari of the NGO Forest and Wildlife Conservation Society stressed that SGNP is a very fragile ecosystem.

Bilal Habib, a scientist with WII who is looking after the twin tube tunnel study, said the WII’s ‘take’ is that you cannot have an impact when the tunnel is not in place. You cannot study it because there are no examples and every place has different characteristics.

“MMRDA told us to conceive the wildlife study,” Habib said. “Hydrological and all [other aspects] has been done by IIT-B. Our specific TOR [terms of reference] is, since impact on wildlife is continuous, to check if there is going to be any impact. This sort of tunnel going below a protected area is not there anywhere else.”

When asked about the effectiveness of the study once the project is over, he said, “Tunnel will be done but at least we will have background information and if there is impact, that impact will be mitigated. Prima facie I don’t think vibrations will go that deep but we don’t know, as of now we don’t have any evidence. It is a gut feeling. Even the burrowing animals found in SGNP are surface burrowers, they don’t go beyond half a metre or so. The tunnel is so deep that I don’t visualise impact, but we don’t know.”

Director of SGNP G. Mallikarjun told IndiaSpend that it has been communicated to them that WII is doing the study before, during and after the construction but when asked about the discrepancy, asked us to speak to higher authorities.

Vishal Jambhale, superintending engineer at MMRDA, concurred. “WII suggested this. Their studies are seasonal. It is an autonomous body under MoEF, whatever they say is the mandate,” said Jambhale. “Had this study been needed before the launch, we would have had to wait for more than a year. But just doing a study before the project and not correlating it with the impact during and after does not make sense.”

The Union environment ministry’s in-principle approval for the project is valid only for two years, and it can be deemed null and void for failing to meet compliance conditions.

“We should be proud that we have an urban national park of the world, we should preserve it,” Tiwari said. “It is one of the best examples of co-existence where leopards and humans stay together. There needs to be a public hearing for projects like these, residents of Mumbai should have a say.”

In the city that came onto the streets under the Save Aarey banner, its only national park now stands open to the pressure of infrastructure projects.