Abstract: There is described an element from tunnel-type metal shuttering, particularly retractable element and means associated with each panel adjacent the bottom thereof and controlled by the rigid structure as it is moved between both end positions thereof, to adjust the panel bottom position and the rolling means position relative to the ground, while insuring automatic levelling of the element in the shuttering position thereof, and means to join each panel from an element to the directly adjacent parallel panel from an element lying side by side when said elements lie in shuttering position.