Beijing's traffic woes will get worse by 2015, experts are predicting, with 7 million cars in the city and traffic jams reducing the average rush-hour driving speed to 15 kilometers per hour.

The situation will be unbearable if the private cars continue to increase at the current pace, 1,900 cars every day, Guo Jifu, head of the Beijing Transportation Research Center, said at a symposium Tuesday to discuss the city's traffic problems.

It took only two years and seven months for the number of Beijing's cars to jump from 3 million to 4 million, while Tokyo used 12 years to fill the gap.

The center said the relatively low cost to drive contributed to the rapid increase of private cars in Beijing.

If the growth rate continues, Beijing's current total of 4.4 million cars will hit 7 million by 2015, Guo said. The center said Beijing's roads could only support 6.7 million vehicles. Seven million cars means the parking lots needed would take up the whole downtown Beijing, and still not be enough.

Figures with the municipal commission of transport showed in the first half of this year, Beijing drivers are averaging 24.2km per hour during weekday morning rush hours, 3.6 percent slower than the average morning rush hour speed last year.

About 40 percent of Beijing's car trips are for less than 5 kilometers. Car owners in Beijing like to drive wherever they go, no matter how near it is, the report said.

The average annual mileage of car in Beijing is 1.5 times more than that of a car in London and twice as many as a car in Tokyo.

Beijing's private cars are now kept off the roads one day a week according to their plate number. In addition, Beijing in April introduced staggered working hours to ease the traffic pressure.

The measures have not dampened the city's booming auto sales. But Guo said the traffic authority will not consider controlling the sale of cars.

Mayor Guo Jinlong said in his government report in January that the city government plans to get more people out of cars and onto public transport mainly by extending 12 light-rail and subway lines and opening more express bus lanes in 2010.