Mumbai: A part of Mumbai’s skyline on the eastern side has undergone a drastic change over the last few months, with concrete piles, piers and segments coming up at a rapid pace for the country’s longest sea bridge across the city harbour.
Severely delayed by the pandemic, the 22-km Sewri-Nhava Sheva Mumbai Trans Harbour Link (MTHL) might just be ready by the September 2023 deadline — thanks to an ‘acceleration plan’ put in place last year by the Mumbai Metropolitan Region Development Authority (MMRDA), the Maharashtra government agency implementing the project.
“The plan involved multiple shifts, multiple work fronts, strategic planning and execution, constant monitoring and field visits,” MMRDA Commissioner SVR Srinivas told ThePrint.
A massive part of the project is now complete due to the ‘acceleration plan’. Hence, the September 2023 deadline — which had seemed ambitious a year ago when Covid-induced lockdowns severely hampered construction — now looks attainable, according to the latest quarterly report sent by the MMRDA to financing body Japan International Cooperation Agency (JICA), accessed by ThePrint.
“We put the acceleration plan in place around July last year, and now we can hope for the MTHL to be complete by September or latest October 2023. Without the acceleration plan, the project would have probably dragged on till even 2025,” Srinivas said.
The MTHL — connecting Sewri in south Mumbai to Nhava Sheva on the mainland over the sea — will be a key link to the under-construction Navi Mumbai International Airport. It is also expected to speed up residential and commercial development in Navi Mumbai by enhancing access to mainland Maharashtra from the island city.
Construction of the project began in 2018. The MMRDA was originally hoping to complete it by 2022, but work slowed down due to Covid lockdowns and the resultant return of migrant labourers to their native places.
Four times the labour, more shifts, 40+ high-level meetings
The MMRDA’s “catch up plan” or “acceleration plan” involved labour working in three shifts instead of the earlier two, as well as starting work on multiple fronts parallelly, rather than approaching the project sequentially.
The daily average manpower at the MTHL construction sites was multiplied by more than four times as compared to the cumulative average, while the number of man hours spent in construction also surged, Srinivas said.
“Between July and now, we must have had about 40 review meetings at my level, other than the engineer-level meetings, and more than 20 site visits,” he added.
Actual construction of the MTHL has been underway in three packages. The first package comprises almost 50 per cent of the bridge, involving construction of 10.38 km of the bridge across the harbour, including the interchange at Sewri. The second package involves building 7.8 km of the bridge, while the third package comprises construction of the remaining 3.6 km of the bridge, including the interchanges at Navi Mumbai.
According to the MMRDA’s quarterly reports to JICA, work on the first package of the MTHL has cumulatively recorded over 4.4 crore man hours as of 31 March, 2022. Of this, 31 per cent were recorded only in the nine months leading up to March 2022.
Similarly, the cumulative daily average manpower since construction of the project began has been 3,142. That number, for the three months up to March, for the first package went up to 13,848.
In the second package, the cumulative man hours recorded since the inception of the project came to 2.2 crore. Of these, 36 per cent were recorded in the nine months ending 31 March this year. The daily average manpower for the second package has been 10,806 for the January to March quarter, as against a cumulative average of 2,295.
For the third package too, the total man hours spent since the project’s inception came to over 52 lakh, of which 40 percent were recorded in the nine months ending 31 March, 2022. The daily average manpower for the third package also shot up to 2,206 in the January to March quarter as against a cumulative 468.
The leap in the labour force on the site also meant that the contractors could speed up various elements of civil work.
In any bridge construction, the piles and pile caps under the ground are said to be the foundation of the viaduct. The MMRDA has completed almost the entire piling in the first two packages with 80 per cent pile caps inserted in the first package and 93 per cent in the second one. For the third package, 66 per cent of the piles and pile caps have been put in place.
After the foundation come the piers and pier caps, following which contractors erect the segments of the viaduct (a term used for a type of high bridge that comprises arches, piers or columns that support an elevated railway network or road). In the first and the longest package, almost 80 per cent piers and pier caps have been put in place. In the second package, 92 per cent piers and about 78 per cent of the pier caps have been put in place, while for the third package, the percentage of piers and pier caps installed is over 90 per cent.
According to Srinivas, while the additional manpower and extra shifts have helped, the MMRDA also took some strategic decisions with regard to casting and launching segments that helped as well.
“The contractors were saying that the casting yard is insufficient, but that was because the segments were lying there after being casted. We arranged for faster transportation to the site by ensuring speedier launching of the segments. We reduced the turnaround time by at least 40 per cent,” the MMRDA commissioner said.
Over 40 percent of the pre-cast segments in the first two packages have been launched, according to MMRDA’s report to JICA up to March-end. In the third package, more than 60 per cent of segments have been launched.
The work that remains poses two major challenges, Srinivas said. One of them is the launching of Orthrotropic Steel Decks, a complex technology that is being used in India for the first time.
Orthotropic decks provide for spans (the distance between two piers) that are up to six times longer than usual. These are fabricated decks that have a structural steel deck plate that is stressed longitudinally and transversely to become dense enough to bear a high load.
The MMRDA had to construct a new barge “the size of a football field” for launching the decks, according to Srinivas. The authority started launching the decks, which are a part of the first two packages of the MTHL, in December, and the activity is likely to get more frantic in the coming months.
So far, contractors have launched about eight per cent of the decks in the first package and six per cent in the second package.
The second challenge is building the MTHL over the Eastern Freeway, an elevated road linking South Mumbai to the city’s eastern suburbs, which was opened for public use in 2013, and has since then become a key arterial connector.
“For this, we will have to take night blocks on the Eastern Freeway for six months to complete the work,” Srinivas said.
(Edited by Gitanjali Das)