Under the proposal, passengers would travel between downtown Chicago and O'Hare airport in 16-person vehicles travelling at 240km/h, slashing travel time to 12 minutes, from the current 30-45 minutes Chicago has selected Elon Musk's Boring Co to build a futuristic US$1 billion underground transit system that will whisk people from Chicago's downtown Loop district to O'Hare International Airport at 240km/h, the billionaire entrepreneur and Mayor Rahm Emanuel said on Thursday.