The announcement is the most concrete yet from any group working on a Hyperloop design. But building a brand-new transportation system is difficult, and if California’s High Speed Rail project has taught us anything, cost, time, and feasibility projections can belie how difficult executing such a project actually is. For perspective, Ars spoke to Gil Tal, a researcher and faculty member with the Institute of Transportation Studies at the University of California, Davis, who said that he had little doubt that a Hyperloop was technically feasible. Still, “I don’t know if Hyperloop actually makes sense economically,” Tal said. “I think probably technological barriers are not that hard to overcome.”