On the bus, my friend told me a funny but logical theory. It goes like this: In Singapore, bus gets better treatment than cars. (e.g. There is a special lane for buses but not for cars. ) As the advantage of travelling by bus than by car increase, and the advantage of driving a car decreases(e.g. price hike, increase in tax), more people will switch to buses. However, as more people take buses, the road will be crammed with buses, not cars. Then, people will switch back to car again. It's a cycle, isn't it?