More than 50 of an estimated 60 metres of debris have been bored through, says Deepak Patil, a senior officer leading the rescue.
Rescuers are just six or seven metres from 41 men trapped in a collapsed tunnel in India, officials have said.
The low-wage workers from India’s poorest states have been stuck in the three mile (4.5km) highway tunnel in Uttarakhand for more than two weeks.
They are stranded 650 feet (200m) from the entrance.
Last week, a drilling machine broke down, delaying the rescue operation.
But on Monday, so-called rat miners were brought in to drill through the rocks and gravel by hand.
A dozen men are taking turns with hand-held tools, said Kirti Panwar, a state government spokesperson.
They made good progress overnight, officials said.
“About six or seven metres are left,” said Deepak Patil, a senior officer leading the rescue.
More than 50 of an estimated 60 metres of debris have been bored through, he added.
Asked whether the men could be reached on Tuesday, he replied: “Sure, 100%.”
Pushkar Singh Dhami, the chief minister of Uttarakhand, previously said the damaged drilling machine would be removed by Sunday.
Syed Ata Hasnain, a member of the National Disaster Management Authority, said the operation was becoming “more complex” and the machine’s failure would slow the process.
The men have been receiving food, water, light, oxygen and medicines through a pipe.
“We have to strengthen our brothers stuck inside,” Mr Hasnain said. “We need to monitor their psychological state.”
Mr Dhami told reporters, however: “They are in good spirits. They said, ‘take as many days as you require, don’t worry about us’.”
The tunnel is part of the £1.2bn Char Dham highway, being built to connect four Hindu pilgrimage sites through a 500-mile network of roads.
While authorities have not said what caused the collapse, there have previously been landslides, earthquakes and floods in the area.
Emily Foster is a globe-trotting journalist based in the UK. Her articles offer readers a global perspective on international events, exploring complex geopolitical issues and providing a nuanced view of the world’s most pressing challenges.