On a summer evening in 2011, two high-speed trains hurtling through the Chinese countryside met in a fireball of twisted metal and shattered glass. The Wenzhou disaster, as it came to be known, killed 40 people and injured nearly 200. The official inquiry traced the catastrophe to a lightning strike that had fried a trackside circuit, making one train “invisible” to the control centre, which then wrongly cleared the line for the train behind.