Capt.H Im a founder member of the Institute of Asphalt Technology MIAT and an ex Royal Engineer officer. We actually put a rescue road/track into the Cuillin mountains on Skye using mainly heatherinstead of peat, there was peat there , but very wet, Bridge foundations under bridge support columns back in the 16 and 17th centuries were also supported on sacks of wool. and in modern day techniques roads in parts of Scandanavia are built on blocks of polystyrene where permafrost was year round And as you say , geotextile membranes are widely used to construct roads where drainage is difficult . For modern trafficed roads, with high axle loads really onlt the later combined with a correctly designed substrata , base and surface layer, is suitable .
Its a pity the roller is standing unused due to a flat tyre, Mr Macadam and before him the Romans realised a correctly graded stone would interlock and could remain stable for hundreds of yrs , but compaction to consolidate and tighten the material to reduce voids to the minimum is crucial
Robert Vernon