Part of the 4.5km Silkyara tunnel collapsed on November 12, trapping the workers.
Emergency teams have since been trying to drill up to 60 metres through the debris and insert a 90cm pipe that would allow the workers to crawl out.
National Highways and Infrastructure Development Corporation Limited, one of the five companies building the tunnel, called the installation of the new pipe a “breakthrough” as it would not only provide the workers with cooked food but also help with communication.
They had been given pre-packaged food until now.
“We have achieved our first breakthrough, for which we had been trying for the last nine days and was our first priority,” said Anshu Mansish Khalkho, director of National Highways and Infrastructure Development Corporation Limited.
“A 6-inch [15cm] pipe has been installed and they [the trapped workers] can hear us through it. We will now provide them with food and medical supplies through that pipe.”
The Defence Research and Development Organisation will be introducing two robots weighing 20kg and 50kg, respectively, into the tunnel to help remove rubble.
The development comes two days after emergency workers had to stop the rescue operation briefly to figure out a new strategy after attempts to drill through the rubble to insert the pipe hit a roadblock late on Saturday.
Rescuers have been drilling horizontally through the debris using an American-made auger machine but a cracking sound was heard, forcing operations to pause.
Other alternatives include drilling a perpendicular tunnel with two routes and the insertion of a 15cm pipe as a lifeline, Reuters reported, citing a government document.
Rescue teams from Thailand and Norway, including the one that successfully rescued the trapped children from a cave in Thailand in 2018, have joined the rescue operation.
The tunnel was to be built to connect two Hindu shrines in the Uttarkashi and Yamunotri districts.