Drilled Shafts are also referred to caissons, drilled piers, or bored piles, and consist of circular shafts of varying diameter, drilled to a predesignated depth, reinforced with a steel rebar cage, and filled with concrete. Drilled shaft foundations can support large loads and are typically used where here are large lateral loads or extremely large structures and foundation loads that transfer into the drilled shafts. Drilled shafts are used for bridge foundations, and other ancillary structure foundations such as sign cantilevers and trusses, and signal strain poles. Drilled shafts can be constructed in the dry, or in the wet, and can also include a steel casing.