New Delhi, Dec 18 (IANS): The Delhi Metro Thursday flagged off the trial run on the underground stretch of the Phase III route between the Mandi House and ITO stations, an official statement said.

The section is part of its 9.37-km-long Central Secretariat-Kashmere Gate corridor of Delhi Metro's Phase III network.

"The construction work for this underground stretch is almost complete and is expected to be opened for commuter operations after successful trials and mandatory approvals," a Delhi Metro statement said.

The opening of the stretch, originally scheduled for December 2015 has been advanced since the ITO Metro station will "cater to a large number of office goers".

"As per the Detailed Project Report, approximately 22,000 passengers are expected to use the ITO Metro station by 2016. The number is likely to cross the 31,000 mark in 2021," the statement said.

The work on the stretch started April 2012 and was completed this December - seven months before the scheduled date of July 2015.

"During the trial runs, the interaction of the Metro train with physical infringements (civil structure) will be checked to ensure that there is no physical blockage during the movement of the train. The entire signaling system will also undergo rigorous testing," the statement said.

"In addition, the response of the train at different speeds, braking of the train and the interconnection with the Operations Control Centre (OCC) will also be monitored. The behavior of the track system and the over head electrification (OHE) will be checked repeatedly during all the trials," it added.