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Was 4-track Crossrail considered?

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mister-sparky

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Hey guys! Is there, or has there any been any thoughts or plans to make Crossrail 4 tracks? For fast lines and slow lines, or just to increase capacity. Half of the problems with Thameslink is that it snarls up in the central core because it's such a bottleneck. I can't help thinking that Crossrail is just going to become a disaster because of the same reason.
 
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ainsworth74

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Thameslink is a disaster?

Also not sure much extra capacity is really going to be needed? We're already looking at frequencies of 24tph through the core and surely that's always going to be all-stops so no need for separate fast/slow lines. Outside of the core there might, and I stress might, be a argument to be made for a mix of fast/stopping services but then the infrastructure should already basically exist to allow that to occur if anyone wants to set up. There could well be capacity issue to address if you want to do that but it'll take more than quad tracking as those section are already quad track!
 

The Ham

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There is no point having Crossrail as 4 tracks as the GWML feeding into it is also only 4 track. There maybe some benefit in providing 4 tracks once there are more tracks on the GWML.

One of the big diferances between Crossrail and Thameslink is that Crossrail doesn't currently have any trains running on it, whilst Thameslink did. Therefore the increase in capacity for Crossrail is much higher.
 

edwin_m

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Four tracks for Crossrail would cost twice as much as two tracks, and even if it was used to capacity in the peaks the off-peak traffic would be within the capability of two tracks.

Far better if the funding was available to build two more tracks on a different route, which would provide a wider range of new travel opportunities. It would also be less likely to overload the intermediate stations with passengers.
 

Busaholic

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Four tracks for Crossrail would cost twice as much as two tracks, and even if it was used to capacity in the peaks the off-peak traffic would be within the capability of two tracks.

Far better if the funding was available to build two more tracks on a different route, which would provide a wider range of new travel opportunities. It would also be less likely to overload the intermediate stations with passengers.

Although I totally agree with the gist of your argument, I can't see that 4 tracks would cost twice as much as 2 track, especially on the station side.

Perhaps Thameslink should have been provided with a third, bi-directional track for emergencies (like the Channel Tunnel) though, but I expect Farringdon Station and Snow Hill Tunnel clearances wouldn't allow it?
 

tbtc

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There's folk Oop North bitter enough about the cost of a two track Crossrail - they'd have a coronary if you doubled the costs to design a four track Crossrail! Much better to use the "spare" money for Crossrail Two on a different alignment (Wimbledon to Islington).

With the train operation being automated, and Crossrail originally designed to have only having a couple of "shortish" branches at either end* (i.e. much less complicated than Thameslink is going to be, much shorter than Thameslink is going to be), trains should cope with the central "core" without much fuss.

Crossrail is going to be a simple route, like a grander version of the Central Line, rather than the four track/ freight/ Bristol to Norwich express/ double decker (delete as applicable) line that some enthusiasts want it to be - the reality of Crossrail is probably going to seem quite boring once it opens (efficient, simple, roughly on budget, roughly on time, no doubt well used from day one... but not as "sexy" as the Enthusiast Community would like!).

(* - pre "Tring")
--- old post above --- --- new post below ---
Although I totally agree with the gist of your argument, I can't see that 4 tracks would cost twice as much as 2 track, especially on the station side

FOUR tracks could cost more than double TWO tracks, since a two track railway only has to find a "gap" of a certain width between various underground lines/ rivers/ other tunnels under London - finding a route for a wider railway may be significantly harder.

(I don't know for certain, of course, just explaining that sometimes there are economies of scale and sometimes there aren't)
 

ainsworth74

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Perhaps Thameslink should have been provided with a third, bi-directional track for emergencies (like the Channel Tunnel) though, but I expect Farringdon Station and Snow Hill Tunnel clearances wouldn't allow it?

The Channel Tunnel is fully bi-di (as far as I'm aware) however there are only two rail tunnels (with two cross-overs between them). The third tunnel is a much smaller service tunnel used to get people into the tunnel or, more importantly, out of it. It does not have rails (but the vehicles do have wire guidance but this is buried under the road surface).
 

mr_jrt

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I do find it a strange argument against 4-track railways. The WCML, GWML, MML, GEML, etc. disagree with the sentiment wholeheartedly. I think there is an argument for express trains through the core - the main problem with the SSLs is that they never got their express tracks, so everything becomes an all-stations crawl and services have to either turn back or you waste capacity beyond the merge (you can't squeeze a quart into a pint pot, as the saying goes!). The residual peak services into Liverpool Street mainline station are a symptom of this, most likely due to the Abbey Wood branch.

In a metro context, the NYC subway uses express tracks to great effect.
 
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Class 170101

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Where the two track becomes un-stuck is if Boris wants to run 24hrs a day. As I understand there are no crossover tunnels for Crossrail so this cannot happen. Additonally it will be difficult to find the space under London for four tunnels, two was difficult enough.

Oxford Circus cannot be served (even though the Crossrail is 'parallel' with the Central Line at this point) because when Crossrail was conceived the Post Office Railway was still operating and its tunnels are in the way. The Crossrail TV program also showed how close one of the bores was to the Northern Line (crossing below) and to an escalator shaft (crossing above) at Tottenham Court Road.
 

swt_passenger

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Between Stratford and Ealing Broadway Crossrail could be considered an extra pair of tracks for the Central Line.

I think the main reason they missed out Oxford Circus was to spread the interchange with existing N/S lines out more. People who are aiming for the wider area between the named stations of Bond St and Tottenham Court Rd also have the secondary entrances to the two Crossrail stations at Dean St and Hanover Square...

The four central double ended stations widen Crossrail's coverage considerably.
 

Busaholic

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Where the two track becomes un-stuck is if Boris wants to run 24hrs a day. As I understand there are no crossover tunnels for Crossrail so this cannot happen. Additonally it will be difficult to find the space under London for four tunnels, two was difficult enough.

Oxford Circus cannot be served (even though the Crossrail is 'parallel' with the Central Line at this point) because when Crossrail was conceived the Post Office Railway was still operating and its tunnels are in the way. The Crossrail TV program also showed how close one of the bores was to the Northern Line (crossing below) and to an escalator shaft (crossing above) at Tottenham Court Road.

I believe there are two crossover tunnels, though I can't immediately quote a source for this, beyond newspaper reports from March this year about a construction worker dying 'in the construction of a crossover tunnel at Fisher Street, Holborn': the other, from my unreliable memory, was somewhere between Liverpool Street and Whitechapel.
 

Class 170101

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Between Stratford and Ealing Broadway Crossrail could be considered an extra pair of tracks for the Central Line.

I think the main reason they missed out Oxford Circus was to spread the interchange with existing N/S lines out more. People who are aiming for the wider area between the named stations of Bond St and Tottenham Court Rd also have the secondary entrances to the two Crossrail stations at Dean St and Hanover Square...

The four central double ended stations widen Crossrail's coverage considerably.

Indeed Bond Street and Tottenham Court Road stations bring one each of their respective exits close to Oxford Circus however I understood they would have liked to serve Oxford Circus directly as to relieve the Bakerloo Line between Paddington and Oxford Circus.
--- old post above --- --- new post below ---
I believe there are two crossover tunnels, though I can't immediately quote a source for this, beyond newspaper reports from March this year about a construction worker dying 'in the construction of a crossover tunnel at Fisher Street, Holborn': the other, from my unreliable memory, was somewhere between Liverpool Street and Whitechapel.

Fisher Street is an access tunnel where the death tragically occurred as I recall. Whitechapel is where the Junction between the Greast Eastern and Abbey Wood branches of Crossrail meet.
 
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Busaholic

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Have now found on Crossrail's own web pages mention of a crossover tunnel in the central area, being built right now. It will be beneath Red Lion Square, Holborn, with access gained from that Fisher Street shaft. It doesn't say so, but it may well not have been originally planned. But if there's to be one, surely there has to be a second?
 

edwin_m

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I believe Fisher Street has crossovers both ways. There is no crossover near Whitechapel, just an underground grade-separated junction at Stepney Green. Although the tracks will be bi-directional there would be no point in using them as such in service, as the workable frequency would be too low to bother with. The crossovers become important in emergencies and possibly during engineering hours, and might allow a limited service using both tracks on half the route if the other half is closed.

I was oversimplifying when I said a four-track Crossrail would cost as much as a two-track one, but only slightly. The costs of the stations at platform level would double as there would be two "island" platforms not one, and each would need separate escalator access, PRM lifts and emergency shafts. So the only saving would be at higher levels, and even there everything would have to be bigger to cope with the greater flows of passengers.

As already stated, Crossrail is effectively an express service with the Central Line providing the "slow" and if you like the buses on Oxford Street catering for really local journeys. It already manages to miss the Victoria line and the mega-interchange at KXSP, and taking out any more stations would compromise its usefulness for city centre access and connections to other lines for the benefit of a couple of minutes saving to the few passengers travelling right through London.
 

swt_passenger

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Indeed Bond Street and Tottenham Court Road stations bring one each of their respective exits close to Oxford Circus however I understood they would have liked to serve Oxford Circus directly as to relieve the Bakerloo Line between Paddington and Oxford Circus.

I've just been searching in Hansard on the Crossrail Bill evidence discussions, and there are a large number of quotes about Oxford Circus being ruled out very early on. One major reason was the sheer complexity of the work underground where three lines already crossed, but they also researched the effect on street level pedestrian numbers and found that the streets would not allow for the modelled numbers of exits and entries. It seems the post office tunnels were noted in the process, but they were certainly not the primary reason for missing the station out...
 

macka

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The main purpose of Crossrail is to distribute passengers travelling in from the suburbs around central London rather than pushing them all through the tube at Paddington and Liverpool St. Therefore, Crossrail must stop as much as it can within the core. To have a pair of express tracks through the core misses the point, and it would be a far better use of the money to build another Crossrail line instead to relieve other railway stations and tube lines. The capacity of 24 tph each direction (which can be upgraded) is already huge for a railway line and will be wasted if there is a second pair of tracks because the GWML and GEML will not have enough capacity to fill both pairs of tracks.

The idea of having a separate pair of express tracks works better for linking the suburbs and beyond to the core, just like the railway main lines. The IC services can run through entire areas served by commuter services without stopping - like for example, EMT's Sheffield services won't stop until Leicester (well beyond Bedford) while passing 5-6 Thameslink services travelling in the same direction.
 

ChiefPlanner

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It is very tricky finding a tunnelled route through a complex city like London - and the costs of a 4 track tunnel would be very high , obviously. It is in effect providing a 6 track east-west rapid transit tunnel - by relieving the Central and Circle / Met/ H+C which are over 150 years old in the latter case - very restricted and slow. (Good job the madness of Railtrack in it's most bullish phase of taking over the Circle line and running main line trains through it - conveniently forgetting the 16 or so Met Line trains per peak hour which run through to Aldgate - their idea of micro- cheap and fallible scheme)
 

deltic08

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What I fail to understand is why the tunnel wasn't built big enough for double deck trains to increase capacity for very little increase in cost.
 

Busaholic

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Thameslink is a disaster?

Also not sure much extra capacity is really going to be needed? We're already looking at frequencies of 24tph through the core and surely that's always going to be all-stops so no need for separate fast/slow lines. Outside of the core there might, and I stress might, be a argument to be made for a mix of fast/stopping services but then the infrastructure should already basically exist to allow that to occur if anyone wants to set up. There could well be capacity issue to address if you want to do that but it'll take more than quad tracking as those section are already quad track!

It's outside the core where a rethink might still be in order. All-stations stoppers from Reading and Shenfield (particularly the former) aren't really what's needed, those should continue as now into Paddington and Liverpool Street mainline stations and only the more important stations like Maidenhead, Ealing Broadway, Stratford and Romford served directly. Already on the Abbey Wood side Plumstead is being left out and the same should surely apply to Chadwell Heath and West Ealing. There'd then be the scope to run from Tring, say, as is being mooted and somewhere north of Tottenham Hale as additional semi-fast services joining at Paddington and Stratford respectively, and perhaps get some benefits to N.E. London decades before Crossrail 2.
 

swt_passenger

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What I fail to understand is why the tunnel wasn't built big enough for double deck trains to increase capacity for very little increase in cost.

The trains have to be able to run from Shenfield to Maidenhead, (now Reading) and also through the existing Connaught tunnel, and the existing Heathrow tunnel.
 
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thelem

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The trains have to be able to run from Shenfield to Maidenhead, (now Reading) and also through the existing Connaught tunnel, and the existing Heathrow tunnel.

And there are places where the existing tunnels only just fit, the bbc documentary had an episode about one that it called threading the eye of a needle.

How much bigger would they have needed to be for double deck? Because the tunnels are circular, increasing the height by 40% would roughly double the amount of material that would need to be extracted.
 

HSTEd

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Actually no bigger.

The DfT answered an FoI request on this topic and I believe they said that double deck trains will fit if you rearrange some of the equipment inside the tunnel.
 

swt_passenger

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Actually no bigger.

The DfT answered an FoI request on this topic and I believe they said that double deck trains will fit if you rearrange some of the equipment inside the tunnel.

That's correct, but it remains an academic issue until/unless they do something about the rest of the existing 'on Network' infrastructure.
 

ScotGG

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One of the major questions in future is just how much four tracking there should be on an extension from Abbey Wood to Gravesend/Ebbsfleet. The North kent line there sees 8 trains an hour off peak and about 10 at the peaks with no scope to run more I believe. I suppose if they leave it as 2 tracks then some north Kent services from London Bridge could terminate at Abbey Wood if space to do this?

And then some Crossrail take those paths with other crossrail services terminating at Abbey Wood. Though with such huge housebuilding plans for north Kent and Medway 4 tracking the whole lot would offer real long term capacity. The issues are going over Slade Green depot and cuttings around Dartford I think?
 

Bald Rick

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Half of the problems with Thameslink is that it snarls up in the central core because it's such a bottleneck.

On the contrary, the TL core is, today, about the only part of Bedford to Brighton that isn't operated at capacity in the peaks.
 

AM9

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That's correct, but it remains an academic issue until/unless they do something about the rest of the existing 'on Network' infrastructure.

Even if the existing infrastructure could accomodate double deck trains, it's not clear whether the effective capacity of a high-frequency service would be any better. The dwell times of double deck trains are longer so the frequency would be lower. For all their additional cost and inconvenience, double decker trains only give between 25% and 40% more capacity when standing passengers are accounted for.
 

DownSouth

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Even if the existing infrastructure could accomodate double deck trains, it's not clear whether the effective capacity of a high-frequency service would be any better. The dwell times of double deck trains are longer so the frequency would be lower. For all their additional cost and inconvenience, double decker trains only give between 25% and 40% more capacity when standing passengers are accounted for.
Dwell times are not significantly longer. The passengers, unless stupidity is a contagious disease transmitted by season tickets, will learn how to use them properly as they have done in other places with double-deck commuter trains like Sydney, Paris, Germany, commuter lines near New York City and southern California to name a few.

To get a 40% increase in space is well worth it, and not future-proofing the new tunnels is criminal.
 

Starmill

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Crossrail is going to be a simple route, like a grander version of the Central Line, rather than the four track/ freight/ Bristol to Norwich express/ double decker (delete as applicable) line that some enthusiasts want it to be - the reality of Crossrail is probably going to seem quite boring once it opens (efficient, simple, roughly on budget, roughly on time, no doubt well used from day one... but not as "sexy" as the Enthusiast Community would like!).

I dunno, that sounds pretty exotic to me! ;) Can't remember the last time we had anything at all like that!
 
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