Hyperloop UPV
The Hyperloop UPV concept is a levitating rail-free pod design. Using magnetic repulsion and air cushioning for levitation is expensive and can produce unpredictable forces. The pod is equipped with a hybrid system of permanent magnets and electromagnet units, being able to control lift, so it can hover from the top of the tube. That way, the pod doesn't need so much electricity to be lifted by itself. Propulsion is obtained through expansion of the air with a nozzle, located at the rear of the pod, achieving speeds of up to 1000 km/h. The turbine recovers energy from the flow allowing a more efficient journey. This clean tube layout is said to cut costs in up to 30% of the whole Hyperloop project (about 180m USD) and the possibility to comfortably fit more passengers.
Hyperloop
There is also the criticism of design technicalities in the tube system. Prof. John Hansman has stated problems, such as how a slight misalignment in the tube would be compensated for and the potential interplay between the air cushion and the low-pressure air. He has also questioned what would happen if the power were to go out when the pod was miles away from a city. Prof. Richard Muller has also expressed concern regarding "[the Hyperloop's] novelty and the vulnerability of its tubes, [which] would be a tempting target for terrorists", and that the system could be disrupted by everyday dirt and grime.