THREE additional stretches of normal bus lanes along Raffles Avenue, Raffles Boulevard and St Andrew's Road will be converted to full-day bus lanes starting from Dec 22.

The bus lane along Raffles Avenue starts at Republic Boulevard and ends at Espalande Drive, while the stretch at Raffles Boulevard starts at Nicoll Highway and ends at Temasek Avenue.

The stretch along St Andrew's Road starts at Parliament Lane and ends at Stamford Road.

Currently these stretches of normal bus lanes operate only during peak hours - 7.30am to 8pm - on weekdays and Saturdays, except public holidays.

The increase in the coverage of bus lanes helps to ensure that buses have a smooth path of travel, increasing the speed and reliability of bus services for commuters, the Land Transport Authority (LTA) said in a statement on Monday.

The bus lane scheme is one of several initiatives that LTA has launched as part of the Land Transport Master Plan to improve the speed and reliability of public buses.

Since the expansion of the bus lane scheme, the LTA said it has observed improvements to bus speeds of between 10 per cent to 12 per cent in several areas where bus lanes have been implemented.

With the three new stretches, there will be 23km of full day bus lanes and 155km of normal bus lanes.