The tube design is not final. They included a variety of features to allow some flexibility in designing pods. The radius is smaller than a full-scale hyperloop. Depressurization is not catastropic, as it would be for an oil tanker, so there is no need for a double hull. In fact, some leakage is expected. The real tubes will have airlocks. The test track was originally going to have airlocks, but they were scrapped for complexity.
