The director needed a period-looking elevation for use on-air to illustrate/animate the construction of Tunnel No. 6, the Great Summit Tunnel of the Sierra Nevada for the documentary program "Transcontinental Railroad" (for the PBS series American Experience). The drawing I produced is on the right, and was based on a series of photographs of the actual mountain.
Here's how it was built. Engineers decided to drill a vertical shaft midway along the projected tunnel line. Tunneling would then take place on four faces at a time, as two teams worked inward from the eastern and western ends of the tunnel and two more teams worked back to back from the middle, moving outward.
