The capsule will also be 9 feet (2.7 meters) across and weigh 20 tons, with a passenger capacity of 28 to 40 people. If this is all sounding rather ordinary, there’s still one key spec that makes it more revolutionary, which is its top speed of 760 miles per hour (1,223 kph).
That’s Mach 1. Mach 1 is 1,225 kph.
HTT says one of the capsules would be able to leave a departure station as frequently as every 40 seconds,
Now that’s the key. The key to successful public transport is short gap between vehicles. Train networks can be made to carry much more people if the time between trains is reduced to 40 seconds.