Flexible roads require edge restraint so that they can be consolidated by rolling. Typically edge restraint can take the form of curbs which are haunched with concrete. Such curbs can take the form of precast concrete curbs, cast-in-place concrete (favoured in North America), bricks laid on edge or in soldier-course fashion, setts, or even steel edging. Private roads can be formed with timber edging, as can informal garden paths where the timber will rot away leaving a “natural” edge. Alternatively, on heavy clay soils newly laid flexible paving can be consolidated by rolling against a cut in the earth: this will produce a wavy edge which may be appropriate on rural sites.