When visiting big cities like Beijing and Shanghai, foreigners might get the impression that China is already a nation of car owners. But according to Wei Qingchao , who specialises in traffic and environmental studies at Beijing Jiaotong University, about a third of urban residents walk when commuting and half still ride a bicycle. The Beijing-based China Bicycle Association says the mainland now has about 500 million bicycles. By the end of last year, China had more than 33 million cars. Speaking at a forum on transport development in Guiyang , Professor Wei said the continuing popularity of bicycles might have something to do with the fact that most urban residents lived close to city centres, leaving the commute very short, the report said. 'But on the other hand, Chinese public transport still needs improvement, such as punctuality and speed,' he was quoted as saying. Traffic congestion is common on the mainland and many cities are investing heavily in public transport to solve the problem. The number of buses in cities rose from 136,000 in 1994 to 287,000 a decade later. In Beijing alone, the number will increase to 21,000 by 2010 and the length of the city's subway lines will be extended from 114km to at least 270km. But Professor Wei said only a fifth of urban residents took buses and less than 10 per cent were frequent riders of public transport such as subways.