Basil Jet wrote:

On 2012\03\15 21:03, Denis McMahon wrote:

I wouldn't trust a gps derived position underground even if I could
receive the signals - you don't know how much bouncing about it's done
getting through the soil, pipes, rocks of various types, cables etc above
you, and every signal bounce is a loss of accuracy.

GPS is not accurate enough for laying a surface railway, never mind an
underground one.


Differential GPS is. This isn't your car's satnav, nor your hand-held
Garmin that you take when hiking, it is an extremely precise method of
establishing position with great accuracy using highly sophisticated
corrections of GPS satellite transmissions.

It also takes time to do; your car satnav or hand held GPS receiver
gives you a near instant fix to within a few metres, but differential
GPS takes hours* to give an accuracy of millimetres.

But GPS isn't much use down a tunnel. You can establish precise
positions at the shafts using GPS, but you need traditional methods
from then on in.


[*When I was last personally involved in the late 1990s, it took a
couple of days. I am assuming it has gotten quicker in the last
fourteen or fifteen years.]

On 15/03/2012 11:11, Roland Perry wrote:
In message , at 10:55:45 on Thu, 15 Mar
2012, d remarked:
http://www.bbc.co.uk/news/uk-17365934

There doesn't seem to be much distance between the 2 bores. Surely
they won't
be that close the entire route? Looks like it would collapse.

The tunnel is concrete-lined as the machine moves forward.

I'm more interested in them apparently using GPS 38m underground!

Did they ever choose names for them?

wrote on 15 March 2012
21:38:54 ...
On 15/03/2012 11:11, Roland Perry wrote:
In , at 10:55:45 on Thu, 15 Mar
2012, d remarked:
http://www.bbc.co.uk/news/uk-17365934

There doesn't seem to be much distance between the 2 bores. Surely
they won't
be that close the entire route? Looks like it would collapse.

The tunnel is concrete-lined as the machine moves forward.

I'm more interested in them apparently using GPS 38m underground!

Did they ever choose names for them?

Yes. The one currently at Westbourne Park is named Ada, as I saw today
from a Circle Line train.

The names a
PHYLLIS, after Phyllis Pearsall, who created the London A-Z street atlas
ADA, after Ada Lovelace, who worked with Charles Babbage on his
"analytical engine", and is regarded as the first computer programmer
(Phyllis will be first to start boring at Royal Oak, and I assume she
must be already on the slope leading down to the portal there.)

The others whose names have been announced are VICTORIA and ELIZABETH,
after the two queens; MARY, after Mary Brunel the wife of the famous
railway engineer Isambard Kingdom Brunel; and SOPHIA after Sophia Brunel
the wife of IKB's father Marc Isambard Brunel who built the first tunnel
under the Thames.

http://www.crossrail.co.uk/news/site...ines-announced
--
Richard J.
(to email me, swap 'uk' and 'yon' in address)

So, it's finally really happening.


....... and only thirteen years late.

On 15/03/2012 14:55, allantracy wrote:

So, it's finally really happening.


...... and only thirteen years late.

so it is doing better than Thameslink 2000?

On Mar 15, 2:55*pm, allantracy wrote:
So, it's finally really happening.

...... and only thirteen years late.

It was approved 2007 ... under a Labour government based on the 2005
proposals ... made during a Labour government.

If it is 13 years late by your reckoning it was 1994 when it ought to
have been approved - but it was not - by a Tory government.

The previous study that made as far as a Bill were presented in 1991
to a Tory gov finally rejected in 1994 by a Tory gov.

How do you think now then ?

--
Nick

On Mar 15, 7:02*pm, D7666 wrote:

On Mar 15, 2:55*pm, allantracy wrote:

So, it's finally really happening.

...... and only thirteen years late.

It was approved 2007 ... under a Labour government based on the 2005
proposals ... made during a Labour government.

If it is 13 years late by your reckoning it was 1994 when it ought to
have been approved - but it was not - by a Tory government.

The previous study that made as far as a Bill were presented in 1991
to a Tory gov finally rejected in 1994 by a Tory gov.

How do you think now then ?

Quite - here's a very brief historical background on an archived page
which used to reside on Crossrail's own website:
http://preview.tinyurl.com/8a8funk

If it is 13 years late by your reckoning it was 1994 when it ought to
have been approved - but it was not - by a Tory government.

The previous study that made as far as a Bill were presented in 1991
to a Tory gov finally rejected in 1994 by a Tory gov.

How do you think now then ?


Well therein lies the difference

Tories said we're not doing it and doing it they did not.

New Labour said we are doing it and doing it they did not.

The difference we now call spin.

On Mar 15, 8:44*pm, allantracy wrote:

New Labour said we are doing it and doing it they did not.


Explain.

What did they not do ?

NO WAY was a project like this ever going to get authorised underway
and completed in one term of government. If you really think that you
are more in cloud cuckoo land than I thought. there has been an
election, but that does not undo what was done before.

--
Nick
..

On 2012\03\15 20:44, allantracy wrote:

If it is 13 years late by your reckoning it was 1994 when it ought to
have been approved - but it was not - by a Tory government.

The previous study that made as far as a Bill were presented in 1991
to a Tory gov finally rejected in 1994 by a Tory gov.

How do you think now then ?


Well therein lies the difference

Tories said we're not doing it and doing it they did not.

New Labour said we are doing it and doing it they did not.

The difference we now call spin.

Indeed... you can't bore a tunnel without spin.