LUCKNOW, India (AP) — Rescuers drilled deeper into the rubble of a collapsed road tunnel in northern India on Friday to fix wide pipes for 40 workers trapped underground for a sixth day to crawl to their freedom.

Drilling with a new machine started on Thursday and has covered a stretch of 24 meters (78 feet) so far, Devendra Patwal, a disaster management official, said.

It may require up to 60 meters (195 feet) to enable the trapped workers’ escape, Patwal told The Associated Press on Friday.

Patwal said the rescuers hoped to complete the drilling by Friday night and create an escape tunnel of pipes welded together.

Some of the workers felt fever and body aches Wednesday, but there has been no deterioration in their condition, he said. Nuts, roasted chickpeas, popcorn and medicine are being sent to them via a pipe every two hours.

The construction workers have been trapped since Sunday, when a landslide caused a portion of the 4.5-kilometer (2.7-mile) tunnel they were building to collapse about 200 meters (500 feet) from the entrance. The hilly area is prone to landslide and subsidence.

The site is in Uttarakhand, a mountainous state dotted with Hindu temples that attract many pilgrims and tourists. Highway and building construction has been constant to accommodate the influx.

The tunnel is part of the busy Chardham all-weather road, a flagship federal project connecting various Hindu pilgrimage sites.

About 200 disaster relief personnel have been at the site using drilling equipment and excavators in the rescue operation, with the plan to push 80-centimeter-wide (2.6-foot-wide) steel pipes through an opening of excavated debris.

A machine used earlier in the week was slow in pushing the pipes through the debris, a state government statement said.

The new American Auger machine has a drilling capacity of up to 5 meters (16 feet) per hour and is equipped with a 990 centimeters (2.9 feet) diameter pipe to clear debris. At times, it is slowed down by the pile of rubble.

State officials have contacted Thai experts who helped rescue a youth soccer team trapped in a cave in Thailand in 2018, state government administrator Gaurav Singh said. They also have approached the Norwegian Geotechnical Institute for possible help.