A Grid Framework Structure

An expansion joint for connecting regions of a grid structure including a plurality of tracks containing a first set of parallel tracks extending in a first direction and a second set of parallel tracks extending in a second direction, the second set of parallel tracks running substantially transversely to the first set of tracks in a substantially horizontal plane such that the plurality of tracks are arranged in a grid pattern to form a grid structure including a grid with a plurality of grid cells, each of the plurality of tracks having an upper surface profiled to provide two parallel track surfaces defining a double track for guiding two wheeled load handling devices, the expansion joint comprising:

• a first track element and a second track element, each of the first and second track elements providing a portion of a track of the plurality of tracks, the first and second track elements being elongate, each of the first and second track elements having an interface portion, the interface portions being arranged to slide relative to each other in a longitudinal direction to provide a double track including a two parallel track surfaces extending from the first track element to the second track element suitable for guiding two wheeled load handling devices across the expansion joint,
• wherein the interface portion of the second track element is arranged to be substantially a 180° rotation about a vertical axis of the interface portion of the first track element.