Требования к материалу защитного слоя, на который укладывается геотекстиль

Geotextile material used as a separating layer in the railroad track construction must not prevent water exchange both inside the ballast prism and between ballast material and soils of the main subgrade; therefore it should not be subjected to colmation. Moreover, certain requirements are imposed both upon geotextile materials and the protective layer material on which the geotextile is laid.