Pipe ramming
（重定向自Pipe Jacking）
Pipe ramming (pipe jacking) is a trenchless method for installation of steel pipes and casings. Distances of 30 m (150 feet) or more and over 1,500 mm (60 inches) in diameter are common, although the method can be used for much longer and larger installations. The method is useful for pipe and casing installations under railway lines and roads, where other trenchless methods could cause surface settling or heaving. The majority of installations are horizontal, although the method can be used for vertical installations.