SINGAPORE - Over 800 tests - including running trains at peak frequencies and simulating breakdowns - are being conducted for the new Downtown Line 2.

It is one of the most rigorous testing being done in preparation for the launch of any train line in Singapore.

Said Land Transport Authority (LTA) chief executive Chew Men Leong: "Compared to the launching of the previous lines, we have put in a more comprehensive and extensive testing regime... for normal and contingency operations."

On Wednesday, the media was shown a coupling exercise being performed at the Little India station, where a rescue train was used to couple with a "stalled" train to push it to the next station.

The 12-station, 16.6km DTL2, which will open on Dec 27, will connect commuters in Bukit Panjang and Bukit Timah to the city. On Dec 5, commuters can also try out the new line as part of an open house.

Mr Chew said both the LTA and operator SBS Transit are "well geared" for the official launch.

"One scenario we cannot simulate is to run the trains fully loaded in a live environment... So in the coming months, we will need some stabilising of the train systems and there may be some teething challenges," he added.

Mr Chew said that while the LTA and SBS Transit seek to keep teething issue to a minimum, he also asked for the public's understanding should they occur.

On the opening of the six station Downtown Line 1 on Dec 22, 2013, a 15-minute disruption occurred due to a fault at the Bayfront station.