A 6.65km twin tube tunnel will form the key stretch of Mumbai's GMLR link and will be bored using TBM technology. The work for the 12.2km route will be carried out by Brihanmumbai Municipal Corporation (BMC). The dual tunnel runs underneath Sanjay Gandhi National Park, linking Goregaon and Mulund. This will provide a new, high-speed transport connection linking east and west for the Mumbai Metropolitan Area, helping to address the chronic traffic congestion in the locality.
The tunnels will reach depths of 160m and will lie around 300m apart, each featuring six traffic lanes as well as fire safety systems, traffic control technology and CCTV, utility channels and drainage. Each tube will be driven by a different TBM, with the first having already been delivered from Japan and the second due for delivery at the end of 2025. The launch shaft for the first TBM is being completed at present, ready for the TBM to begin its drive in early 2026.
Meanwhile, a 17km road tunnel is being proposed in South Bengaluru but has attracted some controversy. The tunnel is intended to connect Hebbal and Central Silk Board. But there are environmental concerns as the alignment passes directly underneath the two centuries-old Lalbagh Botanical Gardens.
Critics of the project think that the 15m diameter tunnels, around 50-100m underground, could pose an environmental threat to the sensitive ecosystem of the famous gardens. There are concerns too that construction work could also cause issues for the Lalbagh Rok, a Peninsular Gneiss National Geological Monument.
