Two large Mechanically Stabilized Earth or (MSE) walls are currently under construction at the east end interchange. Crews working on the wall along southbound Dale Mabry Highway are nearly complete and this ramp will serve as the entrance-ramp from Dale Mabry Highway on the Extension. The wall along westbound Gandy Boulevard east of the railroad tracks will serve as the entrance ramp for drivers merging onto the Extension from the Selmon Expressway and the northbound Dale Mabry ramp heading to St. Petersburg. All MSE walls consist of alternating layers of granular fill or dirt with reinforcing steel to hold everything in place. Once the project is complete, there will be nine MSE walls.