This loading bay comprises a compact structure carrying at least one fold-away ramp and a shelter for closing off the space between the shed and the truck box body at the side and at the top during loading or unloading operations. Said compact structure adjoins the wall (P) of the shed on the outside and is set up with the possibility of being removed longitudinally on guide means for positioning the movable assembly in a position opposite any one of the openings (H) providing access to the shed. The loading bay comprises, additionally, motorized actuating means, at least one bar of sensors for detecting the position of the truck while said truck is being moved closer into position, a light-signalling device and a light and/or acoustic signal warning of the approach of a truck.