Motorists make their way on a Bangkok street during an afternoon rush hours

Transport analysts say the solution to easing congestion in Asia's huge cities lies with mass bus transport systems replacing private cars.

Asia's cities, boosted by economic prosperity, especially in China and India, are facing increasing gridlock unless urgent measures to promote mass transit systems are promoted.

This was the warning from transport analysts during a regional conference in Bangkok on sustainable transportation and air quality.

More than 100 transport specialists from 10 countries at the conference say the solution lies in providing better public transportation systems to lure car owners away from driving.

Heather Allen, a manager with the International Association of Public Transport, says Asian cities need to stress transport systems over private car use.

"At the moment, anywhere in the world, the energy issue is very firmly on the table and the energy efficiency of public transport," she said. "Our experience and our research shows that on average you can go twice as far using public transport as you can with a private individual car."

Asia's love affair with the car appears very strong. In India, car sales in September were up almost 10 percent, while in China vehicle sales were up 33 percent from a year ago to 354,000 units. Both countries have booming economies and growing middle classes.

But experts say such growth aggravates the problems of increasingly crowded cities.

Axel Friedrich from Germany's Federal Environmental Agency says such growth cannot be sustained as traffic snarls increase in cities. Also, he says, more private cars aggravate pollution problems and increase economic costs because workers and cargo get stuck on jammed roads.

"The density of people in a city like Hong Kong, like Shanghai, or Beijing, is 10 times higher than in Europe or the United States," reminded Mr. Friedrich. "So if you try to get the same number of vehicles, what happened in Beijing, you are stuck in traffic. You can not move any more and this of course is not sustainable; so why promote a system you know is not working in the long term?"

But Mr. Friedrich says while Shanghai's government is trying to reverse the trend and put in place more public transportation, such changes are difficult to make.

Transport analysts say that new systems such as underground railways are often too expensive and provide low returns to investors or governments.

The most efficient systems and fastest to implement are bus systems. But Mr. Friedrich says governments often face local political and business interests when trying to put in place such efficient, low-cost transport systems.