Answer: Hong Kong

The Hong Kong subway system isn’t just a little more efficient than other subway systems around the world, it’s so staggeringly efficient by comparison that it exists in a league of its own.

Beneath the streets of Hong Kong is a subway system that is 99.9 percent on time, a feat near unimaginable for other subway systems around the world. While a good part of that efficiency can be attributed to the 10,000 people tasked with maintaining the system in ways ranging from servicing the cars to polishing and repairing the rails, the true genius behind the system is the subway’s central artificial intelligence.

The artificial intelligence is a system carefully built to maximize uptime and efficiency through both careful scheduling of the actual rail routes as well as the maintenance for them. With a sweeping eye that sees farther into the future and more clearly than its human operators ever could, the subway AI ensures the subways cars arrive on time and instructs the human workers to swoop in and complete repairs when the cars leave.