This document provides general considerations to support the design guidance to geotechnical and civil engineers involved in the design of structures in which a geotextile is used to fulfil the function of an asphalt interlayer. The key potential failure mechanisms and design aspects to be considered are described, and guidance is proposed to select engineering properties.

The state of the art is however limited and does not commend any particular design method. This document can be used as a basis for further research on, for example, system selection, design, performance testing, creation of local guidelines.