In 1858 the tunnel used for years by the C&O , bored from both sides of the Blue Ridge at Rockfish Gap met on Christmas Day with an error of six inches. In 1944 the replacement parallel tunnel met with an error of four feet!
So much for progress. <g>
Extrapolating that, the next one should miss by about 32 feet!
Don't denigrate the optical instruments of 150 years ago, nor the men that used them. In 1944, I am thinking that the US Army Corps of Engineers had probably absorbed all the best, most experienced surveyors. Besides, it could have been worse. The error could have been 4 '- 8-1/2". Then you would have had the classic north rail from one end connected to the south rail from the other end.
Jim
here's another sign of progress......
in the mid 1990s, a barge hit a bridge in alabama and knocked it out of alignment. an amtrak train came along, hit the misaligned track at high speed and derailed into the river killing many people. the track was state of the art welded rail. if the rail would have been the older 39' sections, the rail joints would have broken when the bridge was hit, and triggered a stop signal that would have saved all those people.......