How did the two tunnels that made the channel tunnel meet?

Originally posted by MessOnTheFED!
reply to post by andy1033

 

Andy... Ancient Egyptians invented surveying. I realy hate to bust your bubble.

MessOnTheFED!

I personally believe that there where civilization before our modern era. But we will agree to disagree here, on that.

Originally posted by andy1033
reply to post by MessOnTheFED!

 

Thats what i wanted to know. If it was just down to math and surveying, or did they use some sort of laser or something to guide them, that was going through all the rock or something to both ends.

Man you are so dumb! - The only way on Earth light will travel through rock (and for your information most of the channel tunnel was prob not bored through rock ) is for that very laser to BURN through it...

They worked backwards from the point they started digging from

Lasers are straight lines over the distance we are talking about here - nothing more than a hi tec straight edge - man your dumb (or are you trolling)

reply to post by andy1033


Look

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.

reply to post by endisnighe


I dont know the yaar this was constructed so i cant say for sure that GPS was used. It didnt get very efficiant until the 90's. Perhaps solar observation. I dont know how big the gap is. But your are correct in your assumptions that i got this covered. Any surveying questions ill be more than happy to answer. JAYinAr is a surveyor also, i believe.

I love my job!

MessOnTheFED!

reply to post by MessOnTheFED!


Yeah, but sometimes those engineers in your companies are lazy or dumb.

The last three projects that I started I had to rework all of the elevations around my buildings. They had the elevations of the swales for removing the rain higher than the floor elevations of my buildings. I have found that the landscaping and drainage usually have the most problems in the plans and than the curbing elevations.

It was the same firm on all 3 projects. Of course they offered to rework my engineering plan each time for $5000, but I did the work myself. Did I get any kick back from my company for my extra work? Hell no. They told me it was my job.

reply to post by endisnighe


The equipment is only as good as the man running it. Busts do happen sometimes but three in a row from the same company? Sounds like you should use a different engineering company, thats rediculious. And to charge you to come out and fix it. Thats even more rediculious. Sounds like they might have a special ed instrument man.

MessOnTheFED!

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.

Originally posted by MessOnTheFED!
reply to post by endisnighe

 

I dont know the yaar this was constructed so i cant say for sure that GPS was used. It didnt get very efficiant until the 90's.

I would hazard a guess that it was at it's most accurate as a new system... The accuracy may be dropping off slightly now the 'cloud' is getting older and no one seems to be updating the sats (on the GPS system that is).

The accuracy your referring to would be the end user units - you get what you pay for.

edit: Also GPS no good underground lol

[edit on 5/1/2010 by Now_Then]

reply to post by Now_Then


Actually its all about timing. The satellites send signals to the GPS unit and time how long it takes the signal to get back. The satellite is in a known orbit and can triangulate grid coordinates and elevation from this. The government had a "blocker" if you will, on the satellites timing until the 90s. They didnt want civilian GPS to be too eficient because of security reasons. I think the timing was fixed areound 94 or 96 i dont remember. That is why handheld GPS has gotten better over the years.

And yes a new survey grade R8 reciever will set you back an arm and a leg.

MessOnTheFED!

[edit on 5-1-2010 by MessOnTheFED!]

reply to post by buddhasystem


YOu would be suprised about the stuff i know about that the general public wont know about for another 5 years.

MessOnTheFED!

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]

reply to post by jibeho


We're still at it friend. I personally am working on a future strtch of I-49 coming through Louisiana. Ive walked down the centerline and cann tell you it is messy.

MessOnTheFED!

reply to post by MessOnTheFED!


Keep up the good work. I am a former Summer laborer with my local county highway engineers office. We maintained far more than we actually built.

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....