If I remember correctly when I read about it, it was a little further off than mm's.

But yes, basic surveying was used.

They do use lasers and GPS besides the visual now for surveying.

The last surveyors I had using the newer GPS systems were about twice as fast but their systems were much more expensive than the more basic line of sight systems. They gave me the accuracy percentages compared to the line of sight and they were almost as accurate. Actually quite cool field to be in, engineer surveying. Nothing gets done until these guys set up their grid and elevations.

It sounds like MessOnTheFED has this covered.

Construction Site Super here.

My father (who was a civil engineer) used to tell me a story about tunnels..

Two tunnels of about the same length were under construction, one in Europe under the Alps, and one in China.

The European one had German Engineers and, when the two bores met they were off by 2 centimeters. The German surveyer promptly went and shot himself, ashamed of the vast error.

The Chinese kept working their tunnels until eventually they both exited the mountain, never having met. They promptly threw a huge party celebrating the fact that they now had two tunnels instead of one.

Accuracy is matter of culture and what is possible.

Construction began in 1988, 6th of May 1994 was when the tunnel was opened and 6 months later was open to passengers.
I am sure it encountered a few problems during the construction and had to stop on a few occasions,but cant remember what exactly.

Thank God for directing the surveyor dude to this thread, at least we know how it works form somebody knowledgeable. Yes, surveyors can do miracles. Even before the English Channel tunnel, there were multiple subway systems all around the globe, and look, these are also in need of precision.

All of them there fancy surveying techniques worked for the completion of the Transcontinental Railroad as well. From Sacramento to Omaha Nebraska this construction project began from each city and met in Promontory Utah. This railway was so well laid out that Interstate 80 follows its basic route today.

Thanks to our surveyors and engineers. You also successfully built our nations interstate highway system using these same techniques as well.

[edit on 5-1-2010 by jibeho]

Originally posted by Aggie Man

Originally posted by MessOnTheFED!
Its amazing what you can do with a data collector and a total station isnt it. Its called Surveying man. Its my livelyhood. Simple trig functions work wonders dont they.

MessOnTheFED!

LOL!!!! You know, 10,000 years from now, scientists and archaeologists will be baffled at this feat. AND the conspiracy theorists will shout from the mountain tops that the tunnel was built by ancient aliens. Mankind could never be that clever.

It will of course be reported here first

[edit on 5-1-2010 by wmd_2008]

well i think they used really large moles that they domesticated like in the movie ember lol. seriously how the heck do you think they make tunnels thru mountains same principles you know your direction depth your geology you have to go through and do your math and take constant measurments to make sure you are not deviating from path.

The satellites send signals to the GPS unit and time how long it takes the signal to get back.

There is no signal sent back, as the gps you are holding is only a receiver. This receiver calculates its position by receiving timing data from several satelites and then extrapolates its position from that timing data. The positioning accuracy has improved due to the US military removing error data that once only gave accuracy to about 150 metres (about 500 feet).

[edit on 5-1-2010 by smoov]

I doubt that GPS's were used inside tunnels to ensure that they were aligned....