India’s First Undersea Tunnel Nears Completion: Mumbai Coastal Road Project:
The Mumbai Coastal Road Project (MCRP) is a Rs 12,721-crore initiative by the Brihanmumbai Municipal Corporation (BMC) to link Marine Drive to the Bandra-Worli Sea Link. The most significant feature of the project is the construction of India’s first undersea tunnel, which is set to open by November 2023. The 2.07-kilometer twin tunnels run 17-20 meters below sea level, connecting Girgaon to Priyadarshini Park via the Arabian Sea, Girgaon Chowpatty, and Malabar Hill.
Construction Challenges and Use of TBM:
The construction of the twin tunnels involved cutting through complex geological strata using a massive Chinese Tunnel Boring Machine (TBM) and a team of 35 men. The TBM, named Mavala, is the largest ever used in India, weighing over 1,700 tonnes and standing about 12 meters tall. It was manufactured by the China Railway Construction Heavy Industry Company Ltd (CRCHI) and was assembled and launched a year ago.
The TBM has been instrumental in completing the construction of the undersea tunnels. It broke through from the Girgaon end in January 2022 after a year of mining activity, and the second tunnel’s boring commenced in April 2022. The BMC expects to make its breakthrough by the end of May as only 140 meters of mining work remains.
Tunnel Design and Features:
The tunnels have a diameter of 12.19 meters and feature six crosswalks, four for pedestrians and two for motorists. Each tunnel has three 3.2-meter-wide lanes, with two lanes operational and the third used in case of emergencies or increased vehicular density.
The tunnels also have fibreglass facades resembling the Queen’s Necklace, a famous C-shaped promenade on Marine Drive. The entry and exit points are designed to provide easy access to the tunnels, and the crosswalks allow for safe pedestrian and vehicular movement.
Impact on Commute Time:
The MCRP is expected to reduce the 45-minute commute from Girgaon to Worli to just 10 minutes during peak hours. The high-speed coastal road, spanning 10.58 kilometers, connects Marine Drive to the Bandra-Worli Sea Link. The undersea tunnels are a critical component of the project, cutting down commute time and easing traffic congestion in the area.