Through the GMLR, BMC will be creating a twin tunnel and one box tunnel that will run beneath the surface of the Sanjay Gandhi National Park and Film City. As per plan, each twin tunnel will be 4.7 km long, while the box tunnel will be 1.6 km long.
The cost of the latest tender for building the tunnels is estimated to be ₹6,322 crore, which is 35% higher than the previous tender. In 2020, the estimated cost of the project was ₹4,700 crore. The overall technical aspect of the new tender is the same compared to what it was earlier and only the clauses have been freshly drafted. The approximate diameter for each tunnel would be around 13 metres and the depth will vary between 20 metres and 160 metres.