Ministry decided on using TBM technology instead of controlled blast, since the twin tunnels will be passing through the 40 hectares of land within the Sanjay Gandhi National Park (SNGP), therefore to minimise the damage/destruction to the park's biodiversity.

https://www.freepressjournal.in/mumbai/thane-borivali-twin-tunnel-to-take-shape-through-tbm-technology-environmentalists-raise-objection