Uni-Systems Engineering designed, supplied, and oversaw installation of the retractable skylight mechanical drive system for the World Trade Center Transportation Hub Oculus. The retractable skylight is comprised of 40 retractable panels installed along the oculus arch. When closed, the panels cantilever over a 313 foot long opening that varies in width between 17.5 feet at the top and 12 feet at the ends. When open, the panels are positioned over the building structure, out of sight from the building interior below. The skylight panels are driven along Winkel rails that slope 10° up toward the center of the roof. Each driven rail is powered by a 0.75-horsepower electric motor. A carriage on each rail provides the interface between the rail and the skylight panel.