"We compiled our rankings using data and research supplied by Jeffrey Kenworthy, a transportation professor at Murdoch University in Perth, Australia. He measured the world's 84 largest cities on the following criteria: the cost to the consumer and the government, overall investment in improvements, and the speed and safety with which workers are delivered to offices.
Scores were adjusted for gross domestic product, which allowed developing cities like Dakar or Krakow, Poland, to compete with cities from highly developed G8 nations.
Dense cities perform particularly well by our measures. There are only 8,000 full-time residents in the City of London, but there are 320,000 jobs there, according to the City of London Economic Development Office. That sort of commercial density makes the London rail system a very efficient mechanism for delivering people to their offices. The Tube, which is the world's largest urban railway, and commuter trains efficiently move people in and out of the city, whereas cars in such a small space would overwhelm the system."