The Mumbai Metropolitan Region Development Authority (MMRDA) has completed 250 metres of underground tunnelling on the Orange Gate road tunnel project, which is being built to connect the city’s eastern and western corridors through a subterranean route running as deep as 50 metres below ground level.
The agency has also erected permanent segmental lining rings within the completed tunnel stretch, the structural layer that converts raw excavation into a usable tunnel cavity. Over 575 such rings, made from roughly 4,600 precast concrete segments, have been cast so far.
What the tunnel will look like when done
The project involves two parallel tunnels, each carrying two traffic lanes and one emergency lane, with a combined single-carriageway length of approximately 4.8 kilometres. The design speed is 80 km/h. Cross-passages will be built every 300 metres to allow emergency access and operational safety between the two tubes.
The alignment has been planned to avoid disturbing existing buildings, rail lines, and metro infrastructure above and around it.
“Mumbai is entering a new era of infrastructure development where future mobility solutions will increasingly move beyond conventional surface transport systems. Projects such as the Orange Gate underground tunnel demonstrate our commitment towards building globally benchmarked urban infrastructure that enhances mobility capacity while preserving the city’s operational efficiency above ground. This project is an important step towards creating a faster, more connected, and future-ready Mumbai with tunnel road network called Patal Lok road Network.” Devendra Fadnavis, Chief Minister of Maharashtra, said.
What it means for commuters
MMRDA says the tunnel is expected to cut peak-hour travel time on the corridor from around 40 minutes to roughly 5 minutes. For anyone who regularly uses the arterial roads, this tunnel is designed to bypass; that figure reflects how badly congested these routes currently get.
The project also does not require large-scale surface disruption.
“Executing deep urban tunnelling beneath one of the most densely populated city environments in the country requires exceptional engineering precision, planning, and safety management. This milestone reflects the steady and disciplined progress being achieved on this transformative infrastructure project,” Sanjay Mukherjee, IAS, Metropolitan Commissioner, MMRDA, noted.
The machine doing the work
Tunnelling is being carried out using a Slurry Shield Tunnel Boring Machine with a cutter head diameter of 12.19 metres. The machine weighs approximately 2,400 tonnes, stretches 80 metres in length, and is built specifically for coastal and mixed geological conditions, the kind typically found in Mumbai’s underground.
The TBM was refurbished and re-manufactured within India. The slurry shield mechanism maintains continuous pressure against the tunnel face during excavation, which is critical when boring beneath densely built urban areas where any ground movement could affect surface structures.
Where things stand
Beyond the tunnel itself, MMRDA says construction has also begun on above-ground approach structures, including viaducts and ramp sections. The 250-metre tunnelling figure represents early-stage progress on a 4.8-kilometre alignment, and full-scale excavation is described as ongoing.
No completion timeline was mentioned in the authority’s update.