Slip Forming, used to construct a variety of concrete elements and structures, is the technique of moving formwork to allow for the simultaneous extrusion and finishing of concrete.  It is a continuous process which can provide significant time savings in a variety of construction projects.  As concrete is placed, the formwork may be moved either vertically or horizontally.  It can be moved vertically to form chimneys, walls, tanks, silos, and multi-story buildings, and usually provides uniform cross-sections from the bottom of the structure to the top.  The formwork can also be moved horizontally to produce even layers of concrete for highways, driveways, curb and gutter combinations, and median barriers.