H&H provided inspection services and performed machinery analysis on the Toronto SkyDome, one of the largest movable structures in the world. SkyDome comprises four trussed shell panels; two are segments of spherical shells, and two are circular shells. One spherical shell is fixed, and the other three are mounted on bogies with steel wheels that roll on steel rails. Some bogies are powered by electric motors that drive the wheels through enclosed reduction gearing. The roof is normally in the closed position. To open the roof, the movable, spherical shell panel is rolled on a circular track and parked over the fixed spherical shell panel. The cylindrical shell panels are then rolled on straight tracks to rest over the spherical panels.