Bored pile walls are vertical bored piles, acting either as single piles, contiguous (only touching each other) or a secant pile wall with overlapping piles. Piles are mostly installed as cased piles with typical diameters ranging from 60 to 120 cm. When installations have limited clearance, prohibiting the use of standard drilling equipment, special equipment can be used to a degree where it almost undercuts an existing structure.