An intermodal transport container comprising a rectangular frame having enclosed sides, a floor, a top-access roof cover including a retractable roof panel assembly, a first end closure, and an opposing end closure collectively forming an enclosed interior volume for transporting bulk material. The top-access hinged roof cover includes a robust roof panel hinge system that engages with the roof panel assembly. The roof panel opens in accordance with a two stage process: initially having a linear motion where a member of the roof panel hinge system engages with a support beam of the roof panel assembly and a second stage where the roof panel rotates in accordance with the pivotal motion of the hinge of the roof panel hinge system.