Ewebata KJ421 Hydraulic Tunnel Boring Rig - ihe ngwọta kachasị maka mkpa ọwara gị niile na-agwụ ike. Nke a nnukwu igwe na-egwupụta ihe bụ nke a haziri nke ọma iji zute tunnels nke nha dị iche iche, nke nwere akụkụ obe sitere na 16-68 square mita. Igwe na-egwuputa ihe nwere ikike igwu mmiri nke ukwuu, nwere ike igbapu oghere na bolts n'ọnọdụ kwụ ọtọ, nke nwere mmasị na kwụ ọtọ, ma bụrụkwa ihe dị mkpa maka ịrụ ọwara.