An automated storage and retrieval system includes a three-dimensional grid and a plurality of container handling vehicles. The three-dimensional grid includes multiple storage columns, in which containers may be stored on top of one another in vertical stacks. Each container handling vehicle includes a container lifting device having a lifting frame for releasably connecting to a container. Each container handling vehicle is operated on rails at a top level of the grid for retrieving containers from, and storing containers in, the storage columns, and for transporting the containers horizontally across the grid. The automated storage system includes multiple floor elements. Each floor element arrangeable at a top end of a storage column on top of a vertical stack of containers, such that an operator may stand on top of the storage column. Each of the floor elements includes rail-connecting elements at a horizontal periphery thereof. The rail-connecting elements are able to connect to the rails at the top end of the storage column, such that each of the floor element is held at a desired level relative the top level of the grid. The floor elements are stored on top of one another in a vertical stack arranged in a storage column in the grid or arranged in a dedicated column having a cross-section able to accommodate a floor element having a larger cross-section than the containers.