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Old December 1st, 2007, 09:35 PM   #2121
iampuking
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Why are the passengers per day figures on the Bakerloo line significantly lower on Saturdays, yet higher on Sundays? From the TfL website: http://www.tfl.gov.uk/tfl/corporate/...rloo#section-2

Why are drivers so scared to close the doors? Today the driver on my train said "Mind the closing doors" about 20 times before finally shutting the doors, then reopening them again for some more "mind the closing doors"... It's just... annoying!

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Old December 2nd, 2007, 12:21 PM   #2122
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Quote:
Originally Posted by iampuking View Post
Why are the passengers per day figures on the Bakerloo line significantly lower on Saturdays, yet higher on Sundays? From the TfL website: http://www.tfl.gov.uk/tfl/corporate/...rloo#section-2

Why are drivers so scared to close the doors? Today the driver on my train said "Mind the closing doors" about 20 times before finally shutting the doors, then reopening them again for some more "mind the closing doors"... It's just... annoying!
That's got to be a typo... There's a digit missing off the Saturday figure, it ought to be 190,000-odd. The information about the management is years out of date too.
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Old December 2nd, 2007, 06:47 PM   #2123
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It said that National Rail's tracks are managed by Railtrack in another section!
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Old December 2nd, 2007, 11:02 PM   #2124
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Crossrails tunnels are going to be twin tubes.
http://www.crossrail.co.uk/80256B090053AF4C/Files/informationsheets68/$FILE/j5397_r3_info_tunnels_w.pdf
So were the JLE.

Why not two or three tracks in one tunnel so its easier to access and provide crossovers?
Or two tubes with two tracks in each so you can have stopping and fast services.
I'm guessing engineering issues such as wind resistance and maybe safety issuses for detrainments?

Last edited by Acemcbuller; December 3rd, 2007 at 12:07 AM.
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Old December 2nd, 2007, 11:28 PM   #2125
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Quote:
Originally Posted by Acemcbuller View Post
Crossrails tunnels are going to be twin tubes.
http://www.crossrail.co.uk/80256B090053AF4C/Files/informationsheets68/$FILE/j5397_r3_info_tunnels_w.pdf
So were the JLE.

Why not two tracks in one tunnel so its easier to access and provide crossovers?

I'm guessing engineering issues such as wind resistance and maybe safety issuses for detrainments?
Probably cheaper. That's one big tube you're thinking of by putting 2 mainline tracks in one tunnel.

Same with the channel tunnel and all other tube lines.
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Old December 3rd, 2007, 12:22 AM   #2126
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Why was Paris Metro Line 14 constructed with this method then?

And how are stations like this constructed, this is in the St Petersburg Metro, you can find similar stations in Paris and, surprisingly, in Liverpool! It's deep level, not cut and cover like Baker Street which is a similar shape.

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Old December 3rd, 2007, 01:36 AM   #2127
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Yes but if you extrapolate the tunnel profile to an entire line of tens of kilometres you're excavating millions of tons of spoil for nothing: you end up with lots of empty space within the tunnel bore whereas single bore tube tunnels are almost entirely occupied by the train, so no wasted tunnelling.

The smaller the bore, the more structural integrity and therefore the less sturdy the walls need to be. One big bore would need much thicker walls than a single track bore.
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Old December 3rd, 2007, 03:22 AM   #2128
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I think it's more complicated then that, heres an image from an argument I had with someone (don't ask)



That's the design for a deep level column station (in Moscow)

From a laymen's perspective, i'm thinking that the outer tubes are overlapped further, to create a single vault, using three TBMs (or using the same one three times, who knows) rather than using one massive TBM

So basically, it's like building a tube station but just overlapping the two bores to create a single vault?

I'm probably wrong though...
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Old December 3rd, 2007, 04:58 PM   #2129
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iampuking - you mentioned the Liverpool twin-bore. From what I read on the merseyrail thread that's from an older part of the railway, built in the steam days I imagine, when twin bore must have had steam and smoke ventilation benefits do you think? Tubeman - would you agree? When it was extended into the modern merseyrail network it was all single bore on the new sections, obviously achieving lower construction costs. The cross section of the russian station above shows this is a station on a dual single bore line.
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Old December 3rd, 2007, 07:56 PM   #2130
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Quote:
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iampuking - you mentioned the Liverpool twin-bore. From what I read on the merseyrail thread that's from an older part of the railway, built in the steam days I imagine, when twin bore must have had steam and smoke ventilation benefits do you think? Tubeman - would you agree? When it was extended into the modern merseyrail network it was all single bore on the new sections, obviously achieving lower construction costs. The cross section of the russian station above shows this is a station on a dual single bore line.
Thats true. None of the tunnels built exclusively for electric trains are double track. Its just a question of the ease of excavation and the amount of material to be excavated.

The only exception to that rule I would think would be in the case of cut and cover tunnels where it probably makes sense to dig a single tunnel for two tracks rather than two independant ones in order to minimise the overall width of the excavation, which might be taking place under a street with buildings either side. Often, structural supports would be constructed between the tracks.

I think that the St Petersburg station has been constructed in that fashion purely for architectural effect. Normally, two adjacent single platform bores would be built side by side.
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Old December 3rd, 2007, 08:38 PM   #2131
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I know it was built for architectural effect, but I was more interested in how it was built.
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Old December 4th, 2007, 01:14 AM   #2132
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Are all the discarded newspapers recycled?
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Old December 4th, 2007, 01:54 AM   #2133
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Are all the discarded newspapers recycled?
Really reaching for questions now.
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Old December 4th, 2007, 02:12 AM   #2134
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What would be the point of that? Am I scraping the barrel or flogging a dead horse?
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Old December 4th, 2007, 04:29 PM   #2135
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Quote:
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I know it was built for architectural effect, but I was more interested in how it was built.
The Moscow column station was probably built by first constructing the running tunnels (probably using a TBM) and then using conventional shoring and tunnelling methods to excavate the central arch, following on from the installation of the support columns.

The St Petersburg one is a bit of a mystery as the arch springing points seem to be directly above the platform edge with no columns supporting. I suspect that the ceiling that can be seen is a false one and the structural lining of the tunnel is some distance above.

This is almost certainly a bored tunnel but the span is very large. (A cut and cover with this span would require some colossal roff beams). The closest British equivalent to that, which I can think of, is the old Liverpool Overhead Railway Dingle underground station, which is now closed. This was constructed in sandstone rock and had a span of over 50 feet - being the widest station tunnel in Britain. Even so, comparisons of the photographs seems to suggest that the St Petersburg station is wider.

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Old December 4th, 2007, 05:23 PM   #2136
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So you think that the St Petersburg metro station and that Liverpudlian example are both constructed with similar methods?

Parisian RER D Magenta station is similar:



And Paris Metro Line 14 Olympiades

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Old December 4th, 2007, 07:31 PM   #2137
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The Liverpool tunnels were constructed a hundred and more years ago and would have used very traditional techniques with hand excavation, wooden shoring and the construction of a brick lining. Fortunately, the sandstone rock through which they are excavated is ideal for that form of construction.

The Paris and St Petersburg examples may well have been constructed in clay or other soft ground necessitating more sophisticated techniques.

One way of constructing large underground structures is by using the New Austrian Tunnelling Method. This was used for the huge 18m. wide crossover caverns constructed in underwater stretches of the Channel Tunnel.

This technique involves excavating the required tunnel profile and stabilising it with sprayed concrete reinforced with steel mesh. This lining is continually monitored for movement under ground pressure and is strengthened with more sprayed concrete as and where required. Finally, a reinforced concrete internal lining is constructed that forms the main tunnel lining.

The photograph of Magenta station in Paris seems to show concrete lining segments so may have been constructed using a shield to support the ground with the lining installed as the shield is moved forward.

In any event, the ability to construct large spaces underground does make a lot of difference to the attractiveness of an underground system. Not only does it reduce the feeling of claustrophobia but also assists the free movement of passengers.
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Old December 4th, 2007, 08:29 PM   #2138
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Quote:
Originally Posted by iampuking View Post
I know it was built for architectural effect, but I was more interested in how it was built.
It is fascinating for sure, thanks very much too Martin S for the information.
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Old December 6th, 2007, 12:56 AM   #2139
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yo tubeman, been thinking got some more for ya

-do you reckon it would be beneficial to curtail the metropolitan line at baker street, and then increase the capacity on the hammersmith and city? do u reckon it could be done or would the metroland lobby complain too hard about losing thier city link?

-are bakerloo line to somewhere in the bromley andthe northern splitting and extending to croydon seriously on TFLs agenda??

-do you reckon running the fleet line as ashort shuttle from charing cross to fenchurch street would be beneficial??

-finally do you reckon crossrail will change much from now to when it's implemented, like dropping a branch, going for shorter trains, and also now that it's a tfl project surely they can increase the frequency of the core section from 24tph so that bith branches can be served adequately??

cheers tubeman
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Old December 6th, 2007, 01:10 AM   #2140
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Thanks a lot Martin S, it was really interesting.

image hosted on flickr


This is on the Victoria line, it appears there is enough space to squeeze in an emergency walkway if the tracks were moved to the left a tad, does anyone know if this is a possibility?
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