Ploughman
Established Member
Found this article today.
http://www.theengineer.co.uk/in-dep...xcavating-crossrails-tunnels/1012220.article?
http://www.theengineer.co.uk/in-dep...xcavating-crossrails-tunnels/1012220.article?
Precision of tunnelling route 1mm
Programmed steering and monitoring by GPS
About half way down this interesting article, there's a box with the following it it:
How does GPS work underground?
From memory, the Channel Tunnel TBM's were guided by laser, which I find easier to understand.
Or is the (differential?) GPS just used at the entrance points so as to provide an accurate reference and point the TBM in the right starting direction?
Presumably the latter, unless you have a very sensitive receiver and use some form of low-frequency system.
The TBM is currently lying beside the line just beyond Royal Oak, presumably waiting to be launched. Of course, I was out of film.
The Crossrail is a new line intended to alleviate the overcrowding on the Tube, correct?
Is it a distinct system or is it another Tube line? I checked out the website and it wasn't clear.
Hopefully though it will be treated as "tube" for ticketing purposes
The Crossrail is a new line intended to alleviate the overcrowding on the Tube, correct?
Is it a distinct system or is it another Tube line? I checked out the website and it wasn't clear.
Premium fares though will apply to Heathrow.Already confirmed whole line with be valid on Oyster. However once outside the London zonal system, expect fares in line with GW.
Within Île-de-France, all rail tickets are unified, as near as matters.the closests comparable system is the Paris RER (which shares ticketing with their metro but uses completely different infrastructure) except that the RER uses double deck carriages. Our new crossrail tunnels are being built large enough for double deck trains. but there are sections of older lines used which are not yet compatible with double deck trains.
Within Île-de-France, all rail tickets are unified, as near as matters.
In terms of scale and form, crossrail 1 is comparable to RER line A (one branch of which goes within a few stone throws of my old house).
If I remember correctly the crossrail OHLE is not being put high enough to fit a double-decker anyway, but could be raised in theory. The lines outside Paddington are not suitable for double-deckers at any rate.
As far as I know its the Connaught Tunnel which prevents double deck trains from being used. I'm pretty sure that the Heathrow tunnels are big enough to accomodate double deck trains.
There's the North London Line for that sort of thing. I somehow doubt that Crossrail will get any use for freight.Although (in my fevered imagination) it wouldn't surprise me if some enterprising freight company asks about using the tunnels off peak or night time for an east-west freight link some time in the future...
Hmm, the Connaught tunnels were originally going to be repaired/re-lined/otherwise patched up. But more recently they've decided that wasn't feasible/economic. But they are now to be completely rebuilt (using a temporary coffer dam to drain the docks above). So if the're being rebuilt completely then I would assume the current wisdom of building in passive provision for DD stock would apply?As far as I know its the Connaught Tunnel which prevents double deck trains from being used. I'm pretty sure that the Heathrow tunnels are big enough to accomodate double deck trains.
I'm pretty sure that the Heathrow tunnels are big enough to accomodate double deck trains.
Hmm, the Connaught tunnels were originally going to be repaired/re-lined/otherwise patched up. But more recently they've decided that wasn't feasible/economic. But they are now to be completely rebuilt (using a temporary coffer dam to drain the docks above). So if the're being rebuilt completely then I would assume the current wisdom of building in passive provision for DD stock would apply?
Already confirmed whole line with be valid on Oyster. However once outside the London zonal system, expect fares in line with GW.
For what it's worth, the two ends of the Alice Springs to Darwin line were built independently from each end and they met with a mere 4 mm offset. Not bad considering the length of the line is 1,420 km, well over double the length of the WCML from London to Glasgow. But there are no tunnels so it's an easy job!About half way down this interesting article, there's a box with the following it it:
How does GPS work underground?Precision of tunnelling route 1mm
Programmed steering and monitoring by GPS
From memory, the Channel Tunnel TBM's were guided by laser, which I find easier to understand.
Or is the (differential?) GPS just used at the entrance points so as to provide an accurate reference and point the TBM in the right starting direction?
For what it's worth, the two ends of the Alice Springs to Darwin line were built independently from each end and they met with a mere 4 mm offset. Not bad considering the length of the line is 1,420 km, well over double the length of the WCML from London to Glasgow. But there are no tunnels so it's an easy job!
...only to the west!!!
What about the eastern end??? GA???
are they the ones with a route map above the inside of the doors with little neon lights to indicate next station? wonderfully 1970s & seem to still work as well.Pity. It would have been quite nice to be able to bash Z20500s through London!