The invention relates to a rack storage system comprising a storage rack (1) with storage shelves (12a, 12b) having storage spaces (17) for articles in rack stages (16) lying one above the other with a rack aisle (15) extending in between. Several guide tracks with first and second guide rails run along the rack aisle (15) (27, 28). First and second conveyor vehicles (3a, 3b) can be moved on the guide tracks, each of the conveyor vehicles (3a, 3b) having a drive motor (65a, 65b) and an electronic control unit (66a, 66b) and being controllable independently of one another. The first guide rail (27) is equipped with a first contact line arrangement (67) and the second guide rail (28) is equipped with a second contact line arrangement (68), each of the contact line arrangements (67, 68) comprising dedicated contact lines (69, 70). For energy and/or data supplying purposes, current collectors (71a) of the first conveyor vehicle (3a) contact the contact lines (69) of the first contact line arrangement (67) and current collectors (71b) of the second conveyor vehicle (3b) contact the contact lines (70) of the second contact line arrangement (68). The first conveyor vehicle (3a) and the second conveyor vehicle (3b) can be moved simultaneously and independently of one another on the same conveying track.