The use of gabion units is very simple. The structures folded up to the smallest possible volume need to be folded out on the construction site and the edges attached to each other. Before undertaking a gabion design, the type of soil being retained and the foundation soil type should be identified by a soil investigation survey to ascertain the correct parameters to use in design. The box-like volume created in this way is filled up with filling material available near the site. Generally, in the case of structures exposed to frost damage, the filling material is eruptive rock, but some structures - lined with geotextile fabric - can be filled with humus or earth.