Photo Credit: Zephaniah Varley
Seen here is a machine called a roadheader excavating the 4th bore of the Caldecott tunnel near Oakland, California being built by Parsons Brinckerhoff of Antioch, California. A roadheader is a machine with a rotating cutter head that is mounted on a boom and moved around to eat through the rock in front of the machine. A loading device on the front of the machine then gathers the cut rock bits, called spoil, onto a conveyer belt to be moved out of the tunnel for disposal.