Reinforced Soil Slopes (RSS) are very similar to conventional Mechanically Stabilized Earth (MSE) retaining walls however they provide a more economical approach to addressing grade differences.

Depending on the soil used, most permanent slopes greater than a 2H:1V will require some sort of mechanical stabilization for both deep seated and surficial failures. FHWA defines reinforced soil slopes as reinforced soil structures with a face angle flatter than 70 degrees. Much like MSE walls, RSS structures consist of compacted fill that is reinforced with geosynthetic reinforcement placed in horizontal layers relative to the face of the slope. Depending on the steepness of the slope in question, the designer selects a facing to limit erosion and promote vegetation if desired.

Oftentimes Reinforced Soil Slopes are used in a wide variety of applications by transportation agencies as part of their roadway designs. During new construction they may be used to reduce fill requirements or meet right of way (ROW) limitations without the significant price tag of a retaining wall. They can be used to stabilize existing unreinforced slopes or to repair landslides often reusing the same soil.

Next time you are driving along the highway, look at those steep slopes as you pass, because there is a lot of planning and engineering that’s gone into them that you didn’t even know about!