WORK has started on the second phase of the Downtown Line (DTL), which will connect residents in Bukit Panjang and Bukit Timah to the city.

Transport Minister Raymond Lim launched the start of construction on Friday morning in a groundbreaking ceremony near Beauty World Plaza.

The 16.6km DTL2 will have 12 stops and is expected to be completed by 2015. It starts from Bukit Panjang, passes through the Bukit Timah corridor and runs to Rochor.

From there, it will link up with the first phase of the line, which loops around the Marina Bay area and the Central Business District.

The new line is expected to cut travelling times by up to 30 per cent.

Speaking to an audience that included Bukit Panjang and Bukit Timah residents, Mr Lim said: 'Those who live, work and go to school in this area will enjoy a completely new way to travel.'

Residents, however, would have to put up with a series of road traffic diversions as the stations are constructed.

Upper Bukit Timah Road, for example, will be realigned from as early as the fourth quarter of this year for the building of Beauty World station.

However, the Land Transport Authority stressed that traffic capacity will not drop as diverted roads will go through a lane-for-lane replacement.

'As with other major rail construction projects, there will some disruption and inconvenience... I seek the understanding of residents, motorists and other commuters in this area,' said Mr Lim.

The $12 billion Downtown Line is being built in three phases and will be fully completed in 2016. The third phase will eventually run to the eastern part of Singapore, passing through Macpherson and ending at Expo.