When Phil Gaffney, then chief executive of Hong Kong’s MTR Corporation, visited the Tokyo Metro, he encountered a problem. He repeatedly asked what the metro’s target for train reliability was, without receiving an answer. He was asking the wrong question, it eventually emerged. On the Tokyo metro, it was unacceptable for any train ever to break down.

The story illustrates the demanding standards of the metros in the richest Asian countries, one of the world’s fastest growing markets for urban mass transit. Many of the cities such metros serve – including Tokyo, Hong Kong, Singapore and Taipei – are among the world’s most heavily populated and densely packed. These conditions make the cities perfect environments for metros and poor territory for competitors such as the private car.