Are 16 Car Trains feasible on Southern?

[theageofthetra]

On my traction course we were told that a train on the DC line can't exceed a power rating of 15 (each 4 car unit having a rating of 5) if an 8 car has to be rescued by say another 8 car then motors have to be isolated to bring the rating back down to 15. This made me wonder how the Eurostars were treated when they used to run on the DC lines into Waterloo? Perhaps as only the front and rear collected power they were treated as a top and tailed loco hauled service?

 

[AM9]

So it seems that running 16 car trains causes so many problems for just a small increase in route capacity. It requires far more civil engineering, realignment, signalling changes and major upgrading to the power supply that such a small number of extra seats could justify. And when that fills up where do you go?
The more effective solution would be route widening with avoiding lines for the worst congestion spots, in AC of course.
It may be expensuve expensive territory but if the demand was there then it's better than yet more roads that dump the traffic in London with nowhere to accommodate it.

 

[SpacePhoenix]

On my traction course we were told that a train on the DC line can't exceed a power rating of 15 (each 4 car unit having a rating of 5) if an 8 car has to be rescued by say another 8 car then motors have to be isolated to bring the rating back down to 15. This made me wonder how the Eurostars were treated when they used to run on the DC lines into Waterloo? Perhaps as only the front and rear collected power they were treated as a top and tailed loco hauled service?

Eurostars might not have needed all traction motors running when not operating on a high speed line or in the tunnel

So it seems that running 16 car trains causes so many problems for just a small increase in route capacity. It requires far more civil engineering, realignment, signalling changes and major upgrading to the power supply that such a small number of extra seats could justify. And when that fills up where do you go?
The more effective solution would be route widening with avoiding lines for the worst congestion spots, in AC of course.
It may be expensuve expensive territory but if the demand was there then it's better than yet more roads that dump the traffic in London with nowhere to accommodate it.

That probably requires just as much work and would there even be the space the 4 track along the whole route?

 

[Bald Rick]

Eurostars might not have needed all traction motors running when not operating on a high speed line or in the tunnel



That probably requires just as much work and would there even be the space the 4 track along the whole route?

Eurostars were restricted to 3.4MW on third rail, just over a quarter of their rating on LGVs @ 25kV. This is roughly the same as a modern 12 car EMU, but weighing half as much again, thus a bit sluggish. Hence when you got them moving, you made sure nothing got in their way.

It is much less work to build a few extra tracks or flyovers at a few key pinch points than to make the network 16 car compatible. As has been said up thread, longer trains can mean less capacity, particularly where you have closely spaced slow speed junctions. Like South London.

 

[21C101]

Eurostars were restricted to 3.4MW on third rail, just over a quarter of their rating on LGVs @ 25kV. This is roughly the same as a modern 12 car EMU, but weighing half as much again, thus a bit sluggish. Hence when you got them moving, you made sure nothing got in their way.

It is much less work to build a few extra tracks or flyovers at a few key pinch points than to make the network 16 car compatible. As has been said up thread, longer trains can mean less capacity, particularly where you have closely spaced slow speed junctions. Like South London.

Ideally you need six tracks from Purley northwards as far as the selhurst junction complex, but the cost woul be ghastly.

I would look at providing a conection from down fast to down slow at Streatham North Junction, allowing it to be "grade separated" on the fast lines and reinstating the loops at Cheam (including installing the planned - before WW1 - island platform for operational flexibility) first to get a couple of paths from the mid sussex line to Victoria.

I would also install through lines at Hackbridge station to enhance reliability, again with all for lines having platforms for operational flexibility. There is room on the east side as it is undeveloped.

That would buy some time to develop and get funding for a longer term solution.

 

[Bald Rick]

Ideally you need six tracks from Purley northwards as far as the selhurst junction complex, but the cost woul be ghastly.

As Borough Market viaduct and the GEML fast lines prove every morning, a two track railway can carry a lot of trains per hour if they are kept moving at the same speed.

The constraints are platform occupation at some key busy stations (answer - more platforms), and conflicting moves at some key busy junctions (answer - more flyovers).

Fortunately, some have recently opened (eg Gatwick platform 7), some are being built now (Bermondsey dive under, London Bridge new through platforms), some are committed (Redhill new platform), some are in the early planning stages (taps side of nose with knowing look).

There is an excellent series of articles over on London Reconnections re Brighton Line capacity, which the author is mid way through publishing.

 

[edwin_m]

The new bridge at East Croydon looks like it provides enough room for a whole new island (complete with two tracks) on the west side. Also I think the reason for the rather massive structure is that it spans clear across the whole lot with no intermediate structural supports. Thus if a different arrangement of platforms is needed, it's just a question of moving the lifts and stairs.

 

[21C101]

As Borough Market viaduct and the GEML fast lines prove every morning, a two track railway can carry a lot of trains per hour if they are kept moving at the same speed.

The constraints are platform occupation at some key busy stations (answer - more platforms), and conflicting moves at some key busy junctions (answer - more flyovers).

Fortunately, some have recently opened (eg Gatwick platform 7), some are being built now (Bermondsey dive under, London Bridge new through platforms), some are committed (Redhill new platform), some are in the early planning stages (taps side of nose with knowing look).

There is an excellent series of articles over on London Reconnections re Brighton Line capacity, which the author is mid way through publishing.

Interesting post, I was effectively suggesting exactly that for horsham dorking sutton streatham junction, but that would never be enough long term

It is a pity that the land containing the old line that swung west from the fast lines north of east croydon then under them to join the line from west croydon was sold off as this could have been used to build an underpass to grade separate the up london bridge fasts from the down victoria fasts which is the remaining major conflict there. That would help a lot.

A spur from the up redhill line to the up quarry line where they cross at star lane would remove the other - up trains crossing from redhill to quarry at stoats nest conflicting with down quarry line trains at stoats nest jct.

The other thing you might be able to do is add a sixth track between east ans south croydon by moving the retaining wall back (as was done when the fifth track was added)

I cant see solutions involving major urban new land take or tunnelling ever happening in my lifetime.

 

[Yabbadabba]

Even though the signal spacing as designed on the slow lines around Selhurst/Norwood folk/Windmill/Cottage junction to allow 8 car train standing at one junction to be clear of the junction in rear, in practice with professional driving even a 8 car train will block the junction in rear, let alone the 10 car metros wizzing around.

The main line can barely hold a 12 car between signals so it will take a nice sum of money to improve these junctions to take 16 car trains. I think that places like Selhurst triangle one way or another would need to be sorted out 1st to run more or longer trains, or even both, not to mention the terminal stations amongst other infrastructure improvements to make 16 car trains to work.

On a many a morning peak an Up Wallington train will block Glouster Rd Jcn stopping a DN Selhurst spur train, which will block Selhurst Jcn, Stopping an Up Vic Slow train blocking Cottage Jcn preventing the next Up London Bridge Slow train from moving. Or as above but with the Up Wallington train block Norwood Folk Jcn, stopping the Next up London Bridge overhanging Cottage Jcn thus Blocking the Up & Dn Victoria slow lines, with the Dn Vic slow train over hanging Selhurst Jcn, so blocking the next Dn Selhurst Spur train in Selhurst station. Such is the fun of running today's railway through late 1970s designed and early 80s built railway layouts.

 

[Jonny]

So it seems that running 16 car trains causes so many problems for just a small increase in route capacity. It requires far more civil engineering, realignment, signalling changes and major upgrading to the power supply that such a small number of extra seats could justify. And when that fills up where do you go?
The more effective solution would be route widening with avoiding lines for the worst congestion spots, in AC of course.
It may be expensuve expensive territory but if the demand was there then it's better than yet more roads that dump the traffic in London with nowhere to accommodate it.

ERTMS/ETCS level 3 can be fitted to enable "moving block" operation that would improve capacity quite substantially. This has the potential to improve capacity with relatively little cost.

 

[NSEFAN]

Are there any working implementations of level 3?

 

[SamanthaJ1989]

I'm unsure if this would be nescarry outside of commuter hours