It is described an automated storage and retrieval
system comprising: - a rail
system (8) comprising a first set of parallel tracks (10) arranged in a horizontal plane (P) and extending in a first direction (X), and a second set of parallel tracks (11) arranged in the horizontal plane (P) and extending in a second direction (Y) which is orthogonal to the first direction (X), which first and second sets of tracks (10,11) form a
grid pattern in the horizontal plane (P) comprising a plurality of adjacent grid cells, each comprising a grid opening (12) defined by a pair of neighboring tracks (10a,10b) of the first set of tracks (10) and a pair of neighboring tracks (10a,10b) of the second set of tracks (11); and - a plurality of stacks (7) of storage containers (6) arranged in storage columns (5) located beneath the rail
system (8), wherein each storage column (5) is located vertically below a grid opening (12); characterised in that the system further comprises: a multi trolley vehicle (100) for transporting storage containers (6) between the storage columns (5) and at least one deployment area (25, 26, 80), which deployment area (25, 26, 80) provides direct access to an area outside the
grid pattern formed by the first and second sets of tracks (10, 11), the multi trolley vehicle (100) comprising: a trolley
assembly (72) comprising a plurality of trolleys (72') coupled to each other along at least one of the first direction (X) and second direction (Y), where each trolley (72') provides at least one container volume for storing at least one of the storage containers (6) and where each trolley (72') comprises moving devices (14, 15) allowing movement of the trolley
assembly (72) in at least one of the first direction (X) and / or the second direction (Y), and where at least one of the trolleys (72') comprises non-motorized moving devices (14, 15), and a first drive vehicle (70) coupled to the trolley
assembly (72), the first drive vehicle (70) comprising motorized moving devices (14, 15) allowing self-propelled movement of the first drive vehicle (7) and thereby the multi trolley vehicle (100) in at least one of the first and second directions corresponding to the at least one of the first and second directions of the trolley assembly (72), such that the multi trolley vehicle (100) is horizontally movable. It is further described a multi trolley vehicle operated on said storage and retrieval system, and a method of operating the storage and retrieval system.