May 17, 2014 – The Federal Highway Administration (FWHA) is touting the benefits of Rockeries in a new publication. FHWA's Rockery Design and Construction Guidelines (Pub. No. FHWA-CFL/TD-06-006) provides highway designers, inspectors, and contractors with a basis for evaluating existing rockeries and specifying and constructing new ones.
Rockeries are described in the publication as "an engineered system of dry stacked angular rocks placed without mortar, concrete, or steel reinforcement. Often built with local native stone, they rely on the weight, size, shape, and interface friction of the rock elements to provide overall stability. Rock dimensions are generally greater than 450 mm (18 in), while the rock weights are greater than 90 kg (200 lb). The structures achieve stability through the mass of the rocks and inter-rock friction. A retaining rockery supports itself and resists lateral earth pressures, preventing erosion and slope collapse." For more go here.