"The soil mass of GRS systems is reinforced in layers with a polymeric geosynthetic (e.g., geogrids or geotextiles), and the layered reinforcement is attached to facing elements that constitute the outer wall. Because the facing elements are commonly composed of articulated units that are not rigidly attached to each other, the wall is deemed flexible. Various materials, including natural rock, concrete block, gabion, or timber, may be used for the flexible facing. GRS structures are more forgiving to differential foundation settlement thus minimizing the bump that commonly develops between the roadway and bridge. GRS structures are more adaptable to low quality backfill, easier to construct, and more economical than their conventional counterparts.  GRS structures can be put into service quickly, can be built by maintenance personnel, and are especially well suited to projects constructed in areas that are difficult to access with heavy equipment. GRS structures are an economical alternative for temporary structures, because of their easy demolition and the recyclable nature of their components, and for emergency work, because of reduced lead time and lower equipment requirements."

An excerpt from the forward of  NCHRP Report 556 Design and Construction Guidelines for Geosynthetic-Reinforced Soil Bridge Abutments with a Flexible Facing