Retractable stadium roof system with rectangular opening

A retractable roof structure for covering a field having a first axis and a second axis comprising:

• two tracks which are parallel to each other and to the first axis;
• two arches which in plan view are convex and circumscribe the tracks such that each track is along a chord of a respective arch, and in elevational view along the first axis also are convex and extend above the tracks;
• a substantially rigid, laterally extending edge ring which in plan view generally follows the arches;
• a support which supports the edge ring above grade;
• two sets of substantially rigid arch support struts which extend up from the edge ring to the respective arches;
• two sets of track suspending members which extend down from the arches to the respective tracks;
• two fixed roof portions which extend from the edge ring to the respective tracks;
• two retractable roof panels having runners which in plan view overlap the tracks and match the tracks in elevational view along the first axis, wherein the roof panels are convex in elevational view along the second axis;
• means for selectively moving the roof panels toward and away from each other along the tracks to thereby close or open the roof of the structure.