The Ferry Point Tunnel is one of the oldest tunnels in California. The route comprises five tunnels and several bridges. Building works include construction of three road tunnels, five bridges and three junctions. These typically have long entrances and are equipped with escape tunnels or routes. Construction projects include airports, housing complexes, tunnels, and bridges. An additional 6,500 worked on expanding the underground network of tunnels and halls. Seven subway tunnels under the East River were flooded. The railroad comprises 405 miles of rails with 39 bridges and 86 tunnels. NJT owns most of its tracks, infrastructure, bridges, tunnels and signals. This network of bunkers, tunnels, and pillboxes favored the defense. It usually consists of a network of tunnels and numerous entrances. Fans have many applications including in wind tunnels and cooling towers. Tunneling began at the lower portals of the Nevada tunnels in May 1931. The tunnels required of excavation and another of concrete lining. A tunnelling shield is a protective structure used during the excavation of large, man-made tunnels.