To remedy this, Musk envisions what he calls a Hyperloop system. The specifics of how the technology would work are layed out in Musk's proposal, where he writes:
"Hyperloop consists of a low-pressure tube with capsules that are transported at both low and high speeds throughout the length of the tube. The capsules are supported on a cushion of air, featuring pressurized air and aerodynamic lift. The capsules are accelerated via a magnetic linear accelerator affixed at various stations on the low-pressure tube with rotors contained in each capsule. Passengers may enter and exit Hyperloop at stations located either at the ends of the tube, or branches along the tube length."
Based on Musk's projections, the capsules would move at roughly 760 miles per hour, traveling along a network of tubes lined with solar panels that would provide power to the system. And rather than simply offer a pie in the sky vision of the system, the proposal even delves into the minutiae of cost and infrastructure logistics, ultimately estimating that the system would cost just under $6 billion. For some perspective on that number, note that New York City's new 2nd Avenue subway line, which will only span two miles and is mired in old technology, is expected to cost $4.5 billion.
Because he's busy doing trivial things like pioneering commercial space flight and reshaping the auto industry, Musk is reluctant to commit to working on the project himself, instead opting to release the plans to the public to whomever wants to take up the challenge.
Elon Musk, by the way, demonstrates the personality qualities of an ENTP.