Second tunnel boring machine begins digging under Sanjay Gandhi National Park for GMLR

Work on the Goregaon-Mulund Link Road (GMLR) project, which will connect Mumbai's eastern and western suburbs, has picked up pace. The tunnel boring machine (TBM) 'Tulshi', digging the first of the twin tunnels under Sanjay Gandhi National Park (SGNP), has so far excavated more than 270 metres. The second machine, 'Vihar', formally began excavating the second tunnel on Saturday, November 7, 2026.

The GMLR is a 12.20-km infrastructure project connecting the eastern and western suburbs of the Brihanmumbai Municipal Corporation area. It is being built in four phases. In Phase 3 (B), twin tunnels of 5.34 km are being built under the national park between Dadasaheb Phalke Chitranagari in Goregaon (East) and Amar Nagar in Mulund (West). Each tunnel will have three lanes.

'Tulshi' was started on Monday, August 17, 2026, after all technical procedures and tests were completed. Since then it has dug more than 270 metres from Goregaon towards Mulund. Its average speed has so far reached six metres a day. As work progresses, the plan is to raise this gradually to 10 metres a day.

The site acceptance test of 'Vihar' was recently completed successfully. It checked the machine's mechanical, electrical, hydraulic and control systems against set technical standards. The working of all systems, equipment and safety arrangements needed for excavation was examined. It was also confirmed that the machine's various parts are performing at the expected capacity at the work site. 'Vihar' was then declared ready for excavation.

Like 'Tulshi', 'Vihar' works on single shield Earth Pressure Balance (EPB) technology. Its cutter head has a diameter of 14.49 metres and the whole machine is 83 metres long, including a 22-metre shield section and a 61-metre backup gantry section with a three-storey structure. The technology keeps the pressure of the soil ahead of the tunnel under control during digging, which maintains the stability of the ground and allows excavation to proceed safely and as planned.

Each underground tunnel of the project is 6,675 metres long in total. Of this, 5,340 metres will be dug by tunnel boring, and the remaining 1,335 metres includes box tunnels, entry and exit ramps and shafts. Both tunnels have an inner diameter of 13 metres. Each will have three lanes, so vehicles will run on six lanes in all (3+3). Both machines will dig from Goregaon and emerge at Amar Nagar in Mulund West, giving a direct underground route between the eastern and western suburbs. The target is to complete the entire project by February 2029.

A total of 743 structures were being affected by the construction of the retrieval shaft and ramp needed for the final stage of the tunnel in Mulund. Of these, 612 have been removed so far. The remaining 131 are planned to be removed by the end of December 2026 or early January 2027. Families affected by these structures (PAPs) will be resettled in rehabilitation buildings at Kanjurmarg, where work is in its final stage.

Additional Municipal Commissioner (Projects) Abhijit Bangar said that with 'Vihar' now starting the second tunnel alongside 'Tulshi', work on both tunnels will proceed together. He said this would be significant progress towards completing the project within the deadline. The agencies concerned have been directed to implement immediately the measures needed to avoid any delay in excavation. They have also been directed to regularly review progress, available machinery, technical aspects and manpower requirements, and to provide additional manpower and technical staff if needed.