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While the world is seeing an unprecedented crisis with the pandemic, Mumbai, a very important island, and one of the most important cities in India, is seeing a project that was only hitherto imagined. And who else, but none other than Municipal Corporation of Greater Mumbai (MCGM) is executing it.
On 8 June 2015, the coastal road project received its first clearance from the Union Ministry of Environment and Forests, but received the final clearance on 11 May, 2017. There is a long history to the coastal road and one that dates back to 1962, according to information available in the public domain.
Today, the 29.80 km Mumbai Coastal Road Project (MCRP) is an under construction access-controlled expressway with a route connecting Princess Street Flyover in South Bombay with Kandivali in the northern suburbs. In early July, the Brihanmumbai Municipal Corporation (BMC) declared that it has completed 36% of the total work of the coastal road project, against the 40% target it had set for completion by mid-2021. But the pandemic had a large role in delaying most of the plans around the globe.
It also said that 90% of the fill, 68% of the sea wall, and 11% of the double tunnel have been completed. The work of coastal road is going on day and night uninterruptedly!” the BMC said in a statement.
The completed work includes about 470 metres (m) or 25% of tunnelling work of one tunnel and reclamation of 105 hectares (ha) of the total 111ha. At present, the piling work, casting of piers and girders, construction of the ramp work at Marine Drive and tunnelling work are in progress.
The Rs 12,721 crore coastal road that promises to decongest Mumbai — one of the most congested metros in the world — is the city’s most ambitious infrastructure project yet.
Digging deep
In terms of reclamation work, BMC officials have already informed the media that around 90% has been completed. The road will extend the coast up to 100 meters inside the sea. Plans are afoot to reclaim 111-hectare area in the Arabian Sea which is 12 times the size of Oval Maidan at Mumbai’s Churchgate. Of the 111-hectare land reclamation required for the project so far, the civic body has completed about 100 hectares.
Overall, the project is divided in two parts:
Phase 1: The South End – From Princess Street flyover to Worli end of Bandra Worli Sea Link – a stretch of 9.98 km - to be executed by Municipal Corporation of Greater Mumbai – MCGM.
Phase 2: The North End – From Bandra end of Bandra Worli Sea Link to Kandivali – to be executed by MSRDC.
The 8-lane freeway, with 2-lanes reserved for BRTS corridor, will have 22 entries and exits, two earthquake resistant undersea tunnels of 3.4 km each at Girgaum Chowpaty and Malabar Hill, and 13 cross tunnels to be used for emergency. Such is the magnitude of the project.
The entire stretch is expected to be ready by the end of 2023, if all goes well. In its first phase, a 9.98 km section from Princess Street flyover to the Worli end of the Bandra-Worli Sea Link, is expected to be completed by mid-2023. The Coastal Road will be built in two phases. The project will require the reclamation of 415 acres of land from the sea.
Mavala, the Tunnel Boring Machine, has completed digging 500 meters of the coastal road tunnel. The TBM, with its diameter of 12.19-meters, is said to be the country’s biggest road tunnel boring machine. It weighs 2,300 tonnes and is 80-meters long. It is digging on an average of 8-10 meters per day and around 20 meters below the ground at the Priyadarshini park site.
The country’s first undersea tunnel is a set of twin tunnels one for each carriageway. The length of each is 2.07 km from Priyadarshini park to Chotti Chowpatty at Marine drive, close to the landmark Chowpatty beach at Girgaon.
Moving along
From Malabar Hill to the Sea Link, the Coastal Road will mostly be built on reclaimed land, around 50-70 meters inside the sea.
Green zones are developed alongside the freeway on reclaimed land for various public utilities like jogging & cycling tracks and gardens. Walking, jogging and cycling on the promenade will bring a different paradigm of urban comfort. The entire infrastructure shall be a visual delight for Worli.
Flexible roads are also being constructed on reclaimed land. Various MEP works have been taken up at project end which includes area lighting, laying of utility ducts, providing Traffic Management System, providing systems for mechanically operated gates and use of SCADA.
The substructure of intertidal area of interchanges are being constructed by Group Pile method followed by construction of Piers and Pier Cap by in situ casting. The pre-cast segments are erected by ground supported staging arrangements and post tensioned.
The substructure of marine area of bridge and interchanges are constructed by monopile method followed by construction of piers and pier cap by insitu casting. The pre-cast segments are erected by use of launching girder tailor made for the project and then segments are post tensioned.
Reclamation
What the BMC is doing is creating approach roads/dykes to reach the sea wall locations by filling of rocks. The sea wall core layer is being built for a certain length by dumping quarries into the sea by end tipping method. It is also placing rocks of specific sizes using excavators to a specific height of 4 meters above mean sea level.
In June, the Bombay High Court allowed the felling of trees at Tata Gardens, Breach Candy, for construction by vacating an interim stay on it which had restrained the BMC from cutting the trees.
