A tunnel-boring machine of East-West Metro that had been lying idle under Nirmal Chunder Street has moved for the first time since the project came to a halt following a subsidence in Bowbazar on August 31.

Engineers said the movement of the machine did not trigger any significant settlement.

The 16.5km East-West corridor, part of which will run under the Hooghly, will connect Salt Lake Sector V with Howrah Maidan. In the first phase, trains will run between Sector V and Salt Lake stadium, a distance of 5.5km.

Work on the project came to a halt since a machine boring a tunnel hit a aquifer under Bowbazar on August 31, triggering large-scale subsidence. Many buildings developed cracks and hundreds of people had to be relocated.

The machine boring the other tunnel had since been lying stationary under Nirmal Chunder Street, not far from the subsidence zone.

Calcutta High Court had earlier this week given permission to Kolkata Metro Rail Corporation, the implementing agency of the project, to move the machine five metres for maintenance.

“We moved the machine four metres and built three rings of the tunnel. Initially, there were problems in some gadgets. Those were fixed. The problems occurred because the machine had been lying idle for so long,” said British engineer John Endicott, who heads a technical committee asked by the court to suggest whether the machine could be moved or not.

Endicott, who has decades of experience in boring tunnels, said work to start the machine started at 7am on Thursday. “The four-metre journey was completed after midnight,” he said.

The machine was stopped a few metres from where the other boring machine had collapsed after running into the aquifer.

“We are closely monitoring the area and there is no significant soil settlement,” said Endicott, who has worked in Hong Kong, Taiwan, Singapore, Thailand, Indonesia and also in Mumbai and Delhi.

“The machine will now be overhauled for its longer journey to Sealdah and back. Once we are satisfied about the machine’s overhauling, we’ll approach the high court seeking permission for tunnel boring.”

The East-West authorities have decided to use the machine that was moved on Thursday to burrow the east-bound tunnel till Sealdah station. The machine will then make a U-turn to finish boring the other tunnel.

Both machines will be pulled out through a shaft in Bowbazar, said engineers.