[Central Park Tunnel: IRT Lenox Avenue Line]
Tunnel excavation under Central Park, Manhattan during the construction of the IRT Lenox Avenue Line. Note the rolling platform or "traveler" in the newly excavated tunnel. This traveler, which operates on rails placed along the edges of the rock wall, is used to build the concrete sidewalks. The view is north from the west side of the tunnel.
This photo shows tunneling under Central Park for the Lenox Line. Unlike cut and cover, these tunnels are deep underground and cannot be built by digging through the street. Drillers made holes for dynamite that helped explode the rock, and then excavators removed the spoil and cleared the way for the shield, a device that kept workers safe as they dug. The shield is a temporary support that acts to protect the workers from falling debris as they chip away at rocks ahead of the shield and put in place permanent support walls behind it. Sandhogs used pickaxes, shovels, air powered drills, and sometimes dynamite, to break through the rock.
