Crossrail tunnelling to start shortly
 

In message , at 08:36:36 on Fri,
16 Mar 2012, Graeme Wall remarked:
You forget that Polson was Morton's right hand man on the project and
therefore knows everything about it.

iirc he was involved in one of the rival bids (and unsuccessful) bids to
build a bridge instead.
--
Roland Perry

Crossrail tunnelling to start shortly
 

In message , at 10:25:02 on Fri, 16 Mar
2012, Roland Perry remarked:
GPS is not accurate enough for laying a surface railway, never mind an
underground one.

It's accurate to about 10cm (if you employ differential GPS) which
probably good enough for avoiding a 10m obstacle 40m underground.

With an implied "apart from the fact it doesn't work under ground", of
course.

Obviously, you don't use it to measure the distance between the rails
when you are laying the track.

--
Roland Perry

Crossrail tunnelling to start shortly
 

On Fri, 16 Mar 2012 02:58:13 -0700 (PDT)
Colin Williams wrote:
"According to historian Niall Ferguson, of the 125 major European wars
fought since 1495, the French have participated in fifty - more than
both Austria (forty-seven) and England (forty-three). And they've
achieved an impressive batting average: out of 168 battles fought
since 387BC, they have won 109, lost 49 and drawn 10."

387BC? Thats pretty impressive given france as a nation didn't even exist until
the middle ages.

B2003

Crossrail tunnelling to start shortly
 

wrote in message
...
In article , (Mizter T)
wrote:

Tunnel boring to begin from the Royal Oak portal heading eastwards
under central London.

Pictorial:
http://www.bbc.co.uk/news/uk-17365934

"The scheme is currently the largest civil engineering project in Europe."
Really? Bigger than the Gotthard Base Tunnel?

Rule 1. PR departments must exaggerate. They probably believe they are
tunneling from Maidenhead to Shenfield AND from Heathrow to Abbey Wood.
Then they'll double that figure as there are two tracks.

Also see the regular references to the 48 tph train service....

Paul S

Crossrail tunnelling to start shortly
 

In message , at 19:17:39
on Thu, 15 Mar 2012, remarked:
"The scheme is currently the largest civil engineering project in Europe."
Really? Bigger than the Gotthard Base Tunnel?

iirc the cost of the tunnel (and perhaps stations) under London is only
one third of the total project spend. So to some it extent it depends
how much of the project you include.

--
Roland Perry

Crossrail tunnelling to start shortly
 

On 16/03/2012 10:34, Roland Perry wrote:
In message , at 08:36:36 on Fri,
16 Mar 2012, Graeme Wall remarked:
You forget that Polson was Morton's right hand man on the project and
therefore knows everything about it.

iirc he was involved in one of the rival bids (and unsuccessful) bids to
build a bridge instead.

Difficult to disentangle all his myriad claims but IIRC he was allegedly
working on the tunnel project but thought the bridge proposal was a
better option.

--
Graeme Wall
This account not read, substitute trains for rail.
Railway Miscellany at http://www.greywall.demon.co.uk/rail

Crossrail tunnelling to start shortly
 

On Mar 16, 10:59*am, wrote:

387BC? Thats pretty impressive given france as a nation didn't even exist until
the middle ages.

B2003


Perhaps it should have said France and its predecessors.

"387 B.C. Battle of Allia. The outnumbered Gauls, led by Brennus,
defeat the army of the Roman Republic led by Quintus Sulpicius and
ultimately go on to sack Rome itself. "

http://www.militaryfactory.com/battl..._victories.asp

(Massively off-topic, apologies).


----
Colin Williams.

Crossrail tunnelling to start shortly
 

On Mar 16, 7:49*am, furnessvale wrote:
On Thursday, March 15, 2012 10:53:04 AM UTC, Mizter T wrote:
Tunnel boring to begin from the Royal Oak portal heading eastwards under
central London.
So, it's finally really happening.

I'm keeping my fingers crossed and mouth shut. *How many false starts did the Channel Tunnel have that actually involved tunnelling underway?

Several of the Crossrail stations have been under construction for
some time. The ramps down to the portals at Paddington are
substantial.

Moreover, IIRC, the cost of Crossrail has reduced slightly.

Crossrail tunnelling to start shortly
 

On Mar 16, 9:58*am, Colin Williams
wrote:
On Mar 15, 9:38*pm, allantracy wrote:



Yes, you can always rely on the French to be a bunch of poseurs.

Pity they aren’t so good at armies.

"According to historian Niall Ferguson, of the 125 major European wars
fought since 1495, the French have participated in fifty - more than
both Austria (forty-seven) and England (forty-three). *And they've
achieved an impressive batting average: out of 168 battles fought
since 387BC, they have won 109, lost 49 and drawn 10."

(From 'The Second QI Book of General Ignorance', funnily enough).

France is one of the Western European countries today that has an
effective military. The UK is under defended.

Crossrail tunnelling to start shortly
 

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.]