MSE (mechanically stabilized earth) walls from the @southmountainfreeway project in AZ.
MSE walls are common on highway projects around the country. They work by taking advantage of friction - each concrete panel has a metal strap that extends perpendicularly, well behind the wall. As the wall grows higher, earth is compacted on top of the metal straps. As more and more earth forms on top of all of the straps, the wall stands purely because of the friction of the earth on the metal straps.
These type of walls are chosen because they are precast and can be constructed quickly. There’s often huge cost and time advantages to using precast MSE walls as opposed to cast in place walls. #ibuildamerica