After much musing, I've finally figured out the real meanings of traffic signals in China:
RED: Stop. Unless you're a bus, truck, bicycle, policeman, or driving a Volkswagen Santana. In which case, it means Accelerate And Toot Your Horn (thereby intimidating other road users, who may be proceeding through the green light, and forcing them out of your way).
Note that on Chinese roads you can legally make a right-turn on a red light. However, unlike in other, less enlightened countries, you make that right-turn without looking to see if there is any traffic coming from the left. You don't need to look, because there always is.
[There IS a Give Way/Yield rule in China, contrary to popular belief. The rule is: "Last One To Finish Tooting His Horn Gets The Right Of Way". It's also an old Confuscian proverb.]
YELLOW/AMBER: Undefined. There seems to be no consistent behaviour for an Amber light in China. This makes the prevailing driving conditions unpredictable. Therefore most drivers will slow down to under 50 mph. Therefore this is usually the best time for a pedestrian to attempt to cross at a pedestrian crossing.
[Special Note About Pedestrian Crossings: No-one really knows how they came to be there. They are a bit like crop circles in a Wiltshire field. And about as useful for crossing the road! They are certainly not used for giving pedestrians any sort of right-of-way when crossing the street.]
GREEN: Go. But, go carefully. There will probably be some lingering pedestrians. Weave your way through the pack. If you have to (and you will) maybe it would be easier to drive on the other side of the road for a bit? Also, if your light is green, that means there is a red light somewhere close by, so watch out for an enormous blue truck, piled high with watermelons, microwave ovens and chickens. It's going to hit you. Any moment now.... Shit. That was close.