A high-speed Beijing airport rail link built in time for the Olympics won kudos from its first batch of passengers who were whisked from the city's gleaming new terminal to downtown in under 20 minutes.

'Normally I take a taxi and that can take an hour or more,' said Mr Chen Jianlan, a frequent visitor from Hong Kong, taking one of the first trains into town after the line opened Saturday.

The 27-kilometre line links downtown to the massive new airport Terminal 3, which opened five months ago. It also runs to Terminal 2, Beijing Capital Airport's other international hub.

"I am proud to be Chinese," said Ms Zhang Yuzhen, a tour guide travelling on the line that is part of a mass transit upgrade undertaken by the city in time for the Beijing Olympics, which open in under three weeks.

"When you see this fantastic airport terminal, and then you go into the new rail concourse, you just get a lump in your throat," said Ms Zhang.

China is using the August 8-24 Games to present a polished image to the outside world, and the athletes, VIPs and tourists who choose to use the airport rail link when they arrive for the Games could not fail to be impressed, according to businessman Jiang Yong.

"I've been overseas and I think this is pretty good by comparison to what I have seen there," said the 35-year-old salesman for US jet engine maker Pratt and Witney.

At the rail terminal travellers pay 25 yuan (S$5) for a ticket for the ride into town from staff like 25-year-old Li Ge, dressed in a crisp new dark blue uniform.

"Once they get off the plane, one of the first things they see in China will be our smiling faces,"said Mr Li. "'We have been training for six months for this day."

Mr Liu Hongtao, the manager of the airport line, said its key characteristics were high speed and high-tech design.

The trains reach 110 kilometres per hour while passengers watch live television on flat-panel video screens in the air-conditioned comfort of two-tone red and grey upholstered chairs.

Two new subway lines also went into service on Saturday as Beijing strives to improve the public transport system to reduce traffic gridlock and improve air quality ahead of the Olympics.

The new lines, including a link to the main Olympic Stadium, add an extra 58km to the over-stretched subway system at a cost of 22.3 billion yuan.

Their opening coincides with China's last-ditch bid to beat pollution before the Games - Sunday's implementation of broad traffic restrictions that will keep more than one million cars off Beijing's streets during the Games.

Beijing's 3.3 million vehicles - increasing by more than 1,000 a day - have been identified as the chief source of the city's notoriously bad air quality.

Cars with odd- and even-numbered licence plates will be ruled off the roads on alternate days for two months starting on Sunday.