Trains chug around Yangon's circular railway at a stately pace barely faster than a brisk walk, but this creaking relic of colonial times is at the heart of plans for a public transport revolution in the traffic-choked metropolis.Rush hour spills a throng of passengers towards Kyi Kyi Win's cigarette stand at a downtown station, and the tobacconist says she has seen more commuters using the trains since changes to the city's long-neglected network were introduced. "Only poor people used to use the train because the tickets were very cheap," she told AFP, sprinkling rows of green leaves with tobacco and betel nuts -- a mild chewable narcotic -- and folding them into bite-sized parcels for sale at San San Aye station.But upgrades including higher-priced air-conditioned carriages have drawn wealthier customers aboard, delighting Kyi Kyi Win who says the average spend on her betel has soared from 50 kyats per person (five US cents) to 200 kyats.Built under British colonial rule, the railwa