Quay Valley, California
In March 2015, Dirk Ahlborn, the CEO of Hyperloop Transportation Technologies (HTT) in El Segundo, California announced a plan to build a hyperloop test system at the Quay Valley site. Ahlborn indicated that construction could begin in 2016 to be completed in 2017 with the first rides to begin in 2018 if his company can raise $100 million in funding. The company has said that this track will be a fully working and operational creation of the hyperloop, but that running speed will be reduced on the shortened track from Hyperloop's full potential. It is not decided whether a 5-mile loop or straight section will be constructed, and it may cross the Interstate bisecting the site. Ahlborn said that speeds up to may be possible. Quay Hays expects to break ground on the new community in 2016, including a working version of the Hyperloop, estimated to cost $100–150 million.
Arthur Kantrowitz
A recent high-speed transportation option for rapid transit between populous city-pairs about apart, the Hyperloop, has the Kantrowitz limit as a fundamental design criterion. Attempting to pass a high-speed passenger-pod through a very low pressure tube runs squarely into the Kantrowitz fluid flow limit. Historically, the solutions to working within the limit have been "go fast" and "go slow". A major innovation in the Hyperloop proposal provides a novel third approach to remain below the Kantrowitz limit while still moving at high-subsonic velocities: adding a front-end inlet compressor to actively transfer high-pressure air from the front to the rear of the high-speed transport capsule, and thus bypassing much of the air that would have resulted in the dynamic shock of the choked flow. The flow in the smaller duct through the capsule is also subject to the Kantrowitz Limit, this is relieved by increasing the pressure and the density to achieve the required mass flow. In the Hyperloop alpha design of 2013, the air-inlet pump also provides a low-friction air-bearing suspension system for traveling at over .