Light at the end of this tunnel for bullet train
NHSRCL MD SAID THE WORK ON UNDERSEA TUNNEL WILL BEGIN BY SECOND HALF OF 2018
MUMBAI: The legwork for India’s first undersea tunnel, part of the Prime Minister’s ambitious Mumbai-ahmedabad bullet train corridor, has taken off in the city.
The train, which will cover a distance of 508km, has a 21-km underground corridor from BKC to Kalyan Shilphata. Of this, 7km falls under the Thane creek, with 1.8km of it to be built under the sea bed, and the remaining under the mangroves marshland on either side of the creek. While this is the first undersea tunnel in India, the first underwater tunnel was inaugurated for the HowrahKolkata Metro line earlier in 2017.
A team of engineers from National High Speed Rail Corporation Limited (NHSRCL), RITES Ltd, and Japan’s Kawasaki Geological Engineering are currently in Mumbai to initiate phase one of the work of the tunnel. The teams are venturing daily into the Thane creek to get data on the seabed, based on geo-technical surveys. Based on the report of this survey to understand the structure and depth of the seabed at Thane Creek, the team will design the precise alignment for the tunnel. The survey began on December 11 and will be completed by December 24.
Achal Khare, managing director of NHSRCL, said, “We intend to start construction work of this tunnel by the second half of 2018, and complete it by December 2021. We have been surveying this 1.8-km stretch for more than a week, but are deterred constantly because of natural hurdles. However, we have completed 80% of the survey work.”
The team is using static refraction method to study the seabed structure. This involves firing a high-energy sound wave towards the seabed from below the surface of the water, and mapping the refracted sound wave to determine the density of the rock under the sea bed. Only a very dense rock can safely support a tunnel of this nature, Khare said.
A team of more than 10 officials from Japan and five officials from RITES and NHSRCL are working for eight to nine hours a day.