Tube segment for evacuated tube transport system

A double-walled tube section for constructing a double-walled tube segment suitable for underpressure applications,

• wherein the double-walled tube segment comprises an elongated curved outer shell part forming the outer wall of the double-walled tube segment and a plurality of inner shell parts,
• wherein the elongated curved outer shell part comprises an outer shell part curved central portion having outer shell part long edges, and an outer shell part portion folded portion at at least one of the outer shell part long edges wherein the outer shell part folded portion forms a flange folded towards the centrepoint M of the curvature,
• wherein each inner shell part comprises an inner shell part flat central portion having inner shell part long edges, and an inner shell part folded portion folded away from the centrepoint of the curvature at at least one of the inner shell part long edges, the inner shell part folded portion having an inner shell part curved edge to match the curvature of the elongated curved outer shell part,
• wherein the plurality of inner shell parts are joined together along their inner shell part long edges, and wherein the plurality of inner shell parts are joined to the inner surface of the elongated curved outer shell part along the curved edge of the inner shell part folded edge portion.