Subway builders have set aside room in the Dongzhimen Railway Station, the downtown end of the Airport Line, where in the future, passengers will be able to check in for their flights and have their luggage delivered, said Zhou.

But no time-table is immediately available as to when the check-in counters will be set up at the downtown subway station.

In another development, a 4.5-km Olympic Branch Line will carry spectators to the main Games' venues in northern Beijing, and Line No. 10 will run 25 km northwest to southeast in the shape of a right angle.

But before and during the Games, this branch line will open exclusively to participants to the Games, including athletes, coaches, journalists and others, and spectators holding tickets of the day, said Zhou.

"The passengers all need to receive security checks on the ground before they take the Olympic subway to the Games' facilities," he said.

Subway operators estimate the Olympic line would be transporting a maximum of 220,000 passengers daily during the Games. Line No. 10, meanwhile, will probably handle 850,000 passenger trips a day in maximum.

In the meantime, Beijing has been upgrading its two old subway lines, Line No. 1 and 2, to make their facilities air-conditioned and wheelchair accessible.

Yet by the Olympics' opening, some trains on Line No. 1, the city's oldest that runs east to west through the city center, may still run without air-conditioner, said Liu Jian.

Beijing officials said last month that to facilitate public transport during the Olympics, city authorities would increase the number of buses and subway trains and extend their daily operating hours. In addition, 66,000 taxis would provide 24-hour service.

About 2 million domestic tourists and 450,000 overseas tourists will visit Beijing during the Olympics, the Beijing Games organizing committee and Beijing municipal tourism bureau has forecast.