Capacity on Southampton to Waterloo line

[Hammy1966]

Hello All,

I have spent a fair amount of time travelling from Southampton to London Waterloo over the past year (4 days a week) and in my experience over that period I have wondered whether the best use has been made of the capacity on the line and the number of carriages. Obviously, I am fortunate in that I start at Southampton and getting a seat is never an issue. However, the trains are not as frequent as I think they could be and the poor folks at Winchester do not get such an great choice of seats. I have seen some stand all the way to Waterloo in the morning and a couple of times I have had to stand all the way to Winchester in the evening.

Is the bottleneck "arrival slots" at Waterloo or some rule on how close trains can be to each other? Swaythling and St Denys seem wasted stations but I am sure folks at Winchester might love a shorter train that started there?

It strikes me some lessons may be possible from the way the very clever people at NATS manage air traffic and arrivals/departures With limited runway capacity and a very high focus on health and safety and separation.

 

[swt_passenger]

Winchester gets four trains an hour all day once you include the 2 tph semi fasts that come from Portsmouth in the morning peak, and return to Portsmouth in the evening peak. (One of the 2 per hour each way runs in the paths normally used off-peak by the trains to/from Poole, e.g. the xx55 up direction off SOU and xx39 down direction off WAT.) The semi-fasts stop a few times more but effectively Winchester gets nearly twice as many seats towards Waterloo as Southampton. These semifasts are not overtaken so although they are not the preferred service they do soak up passenger numbers. There are also specific morning peak trains that start elsewhere, e.g. at Southampton Parkway.

The main problem is fast line paths inbound from from Surbiton which are running in total at around 24 tph, and then the terminal platform capacity at Waterloo - the latter will be helped by the current works to reopen the international platforms.

I'd recommend reading the Network Rail Wessex Route Study that goes into great detail on what is needed to run more trains on the overall route:

http://www.networkrail.co.uk/long-term-planning-process/wessex-route-study/

Table 3.1 basically defines the current fast line service arrivals in the peak hour at Waterloo, you'll see immediately that the 2 tph from Southampton are only a small fraction of the total. Future alterations such as 5 tracking from Surbiton, OR Crossrail 2, Woking grade separation etc etc, will all contribute to running far more long distance trains.

 

[Muzer]

And yeah, the limit is basically the platforming capacity at Waterloo combined with train headways with the current signalling system. Basically, you'd need both more platforms at Waterloo (they're currently working on that bit), plus trains closer together (needs a long-term solution which I trust is in development — the use of much shorter signalling blocks combined with ERTMS or similar).

With regards to Winchester, it's already been said that they have the Portsmouth trains. I catch the (admittedly quite early) 0717 from Basingstoke each day, and that comes from Portsmouth via Winchester. I always get a seat. So the Winchester people should have no problem — it's their own fault if they instead choose to use the busy Soton services!

 

[edwin_m]

When comparing with NATS, remember that planes can overtake each other and most of them fly at about the same speed anyway. The line northwards from Southampton has only one track in each direction over most of its length, and carries quite a lot of freight though not in the peak hour. The difference in speed between faster and slower trains enforces long gaps behind a slower train, so that the following fast train doesn't catch up with it. The Route Study linked to above proposes solutions such as an extra four-track section to allow overtaking.

 

[MarkyT]

And yeah, the limit is basically the platforming capacity at Waterloo combined with train headways with the current signalling system. Basically, you'd need both more platforms at Waterloo (they're currently working on that bit), plus trains closer together (needs a long-term solution which I trust is in development — the use of much shorter signalling blocks combined with ERTMS or similar).

Plain track signalling headway on the fast lines isn't really the problem. It is theoretically around 100 seconds on the fasts today driving on greens and, if you factor in the traditional Southern electric practice of driving on double yellows that just step up to green as you pass at near line speed, this drops to around 80 seconds. I've seen this standing on Wimbledon station in the peak following a temporary blockage of all lines near Waterloo. The terminus, full of long distance trains, then emptied as quickly as possible with a seemingly endless series of trains whipping through the down fast line platform at Wimbledon at little more than one minute intervals. Very impressive to say the least! Timetable planning headway for normal operations is usually two or three times the technical headway capability, providing some contingency for recovery in real time. ERTMS really comes into it's own where station intervals are short, on the Waterloo slow lines for instance, where the shorter blocks can provide a modern equivalent of 'closing up' signals at every platform in order to implement a metro style operation without the expense of additional colour light signals or the difficulties of weird aspect sequences that have their own risks of misinterpretation. On fast lines, ERTMS with shorter blocks can also cope much better with temporary speed restrictions than colour light signals. A big advantage of ERTMS level 2 is that block length is decoupled from braking distance. You can have block lengths as long or as short as desired for the specified local capacity and performance requirements. Block length can vary along a line to be shorter around critical stations and junctions areas whilst being more spaced out through fast plain line sections to save on equipment cost.

 

[Helvellyn]

Crossrail 2 is something that would free up capacity on the SWML, but that is years off. Essentially the Basingstoke and Alton stoppers, which come off the slow lines at Surbiton (or vice versa on the Down) would stay on the less utilised Slows, possibly along with a two per hour Haslemere stopper.

Essentially you could then have on the Fast lines 14 trains per hour (outside of the peaks): -

• 2 per hour Weymouth - Waterloo [Fast]
• 2 per hour Poole - Waterloo [Semi-fast]
• 2 per hour Portsmouth (via Eastleigh) - Waterloo [Semi-fast]
• 2 per hour Portsmouth (via Guildford) - Waterloo [Fast]
• 2 per hour Portsmouth (via Guildford) - Waterloo [Semi-fast]
• 2 per hour Exeter - Waterloo [Fast]
• 2 per hour Yeovil/Gillingham - Waterloo [extended back Salisbury stoppers - Semi-fast]

Winchester could then have six trains per hour to Waterloo.

 

[Bald Rick]

Suspect Winchester would rather have 6 per hour in the peaks, rather than off peak.

Thankfully Crossrail 2 sorts that too.

 

[Hammy1966]

Thank you very much for sharing the information and your thoughts. I have not yet read up on ERTMS but thinking of short term measures. Are there any? ERTMS and cross rail feel some way off?

 

[Muzer]

Plain track signalling headway on the fast lines isn't really the problem. It is theoretically around 100 seconds on the fasts today driving on greens and, if you factor in the traditional Southern electric practice of driving on double yellows that just step up to green as you pass at near line speed, this drops to around 80 seconds. I've seen this standing on Wimbledon station in the peak following a temporary blockage of all lines near Waterloo. The terminus, full of long distance trains, then emptied as quickly as possible with a seemingly endless series of trains whipping through the down fast line platform at Wimbledon at little more than one minute intervals. Very impressive to say the least! Timetable planning headway for normal operations is usually two or three times the technical headway capability, providing some contingency for recovery in real time. ERTMS really comes into it's own where station intervals are short, on the Waterloo slow lines for instance, where the shorter blocks can provide a modern equivalent of 'closing up' signals at every platform in order to implement a metro style operation without the expense of additional colour light signals or the difficulties of weird aspect sequences that have their own risks of misinterpretation. On fast lines, ERTMS with shorter blocks can also cope much better with temporary speed restrictions than colour light signals. A big advantage of ERTMS level 2 is that block length is decoupled from braking distance. You can have block lengths as long or as short as desired for the specified local capacity and performance requirements. Block length can vary along a line to be shorter around critical stations and junctions areas whilst being more spaced out through fast plain line sections to save on equipment cost.

Cheers for the clarification. I think part of me knew this, I just wasn't thinking straight when I posted! Would I be correct in saying that besides platforming at Waterloo, the second biggest barrier for capacity on the main fasts is differences in stopping patterns?

 

[swt_passenger]

Thank you very much for sharing the information and your thoughts. I have not yet read up on ERTMS but thinking of short term measures. Are there any? ERTMS and cross rail feel some way off?

If you've read the route study now it implicitly recommends that if Crossrail 2 doesn't happen the alternative is a 5 track railway from Hampton Court Junction (south of Surbiton, all the way into Waterloo, which apparently isn't that difficult to achieve within the existing railway boundary, except possibly in the immediate Clapham Jn station area. It would mean a third main line used for the peak tidal flow direction.

It is generally assumed however that Crossrail 2 is most likely to be given the OK, but the build programme has always looked like a planned opening about 10 years after Crossrail 1, the current scheme.

There is also a possibility of reallocating track use to give 5 tracks to the mains through Queenstown Rd and Vauxhall, and provide for an empty stock line as far as Clapham Yard. This would also allow more fast line services into Waterloo in the morning peak, and out in the evening peak

 

[NSE]

Crossrail 2 is something that would free up capacity on the SWML, but that is years off. Essentially the Basingstoke and Alton stoppers, which come off the slow lines at Surbiton (or vice versa on the Down) would stay on the less utilised Slows, possibly along with a two per hour Haslemere stopper.

Essentially you could then have on the Fast lines 14 trains per hour (outside of the peaks): -

• 2 per hour Weymouth - Waterloo [Fast]
• 2 per hour Poole - Waterloo [Semi-fast]
• 2 per hour Portsmouth (via Eastleigh) - Waterloo [Semi-fast]
• 2 per hour Portsmouth (via Guildford) - Waterloo [Fast]
• 2 per hour Portsmouth (via Guildford) - Waterloo [Semi-fast]
• 2 per hour Exeter - Waterloo [Fast]
• 2 per hour Yeovil/Gillingham - Waterloo [extended back Salisbury stoppers - Semi-fast]

Winchester could then have six trains per hour to Waterloo.

There's no way the WofE could handle 4tph each way between Salisbury and Yeovil is there?

 

[Muzer]

Pretty sure there's no way in hell, without redoubling almost all of it.

 

[317663]

Winchester is only a 2 platform station and, given a 3 minute gap between services, such as platforms 8 and 9 at Clapham*, often having one train every three minutes when the slow platforms are OOU. This means it can have 20 trains each way per hour. But saying that, it would cause a bottleneck on Basingstoke, Shawford, swaythling and St. Denys.
Eastleigh has a 4 track station so it wouldn't have much interference.

Just a thought :3

 

[swt_passenger]

The Network is a tree system though, you cannot increase frequency significantly at Winchester to the extent that it inhibits a useful proportion of trains from any other branch. There's also XC and freight passing through Winchester, and the freight takes up more paths than passenger trains.

 

[The Planner]

Timetable planning headway for normal operations is usually two or three times the technical headway capability, providing some contingency for recovery in real time

It shouldnt be anywhere near 3x the technical unless that is quite low itself. A 100 second technical headway shouldnt equate to anywhere above a 3 minute planning one.
--- old post above --- --- new post below ---

Winchester is only a 2 platform station and, given a 3 minute gap between services, such as platforms 8 and 9 at Clapham*, often having one train every three minutes when the slow platforms are OOU. This means it can have 20 trains each way per hour. But saying that, it would cause a bottleneck on Basingstoke, Shawford, swaythling and St. Denys.

You would never plan that way, far too much of a performance risk to fill a line like that.

 

[Helvellyn]

Suspect Winchester would rather have 6 per hour in the peaks, rather than off peak.

Thankfully Crossrail 2 sorts that too.

It would likely get more than 6 tph in the peak. My fantasy off-peak frequency was based on the fact that it's all about clock face timetabling. It also uses 14 paths on the fasts into London - in the 07:00-09:00 peak you could be seeing 26-28 tph on the Fast alone. Who knows what that would look like, but what's to say you wouldn't see a return of non-stop Southampton-Waterloo trains in the peak for traffic west of Southampton, with say a couple of Southampton Central - Parkway - Eastleigh - Winchester - Waterloo crowd busters?

Crossrail 2 would lead to a wholescale timetable recast on the SWML and the potential to do some radical stuff with the longer distance trains. With people prepared to move further and further out of London due to house prices some interesting things could be done.

Just need the small matter of Crossrail 2 being authorised!

 

[The Ham]

Crossrail 2 is something that would free up capacity on the SWML, but that is years off. Essentially the Basingstoke and Alton stoppers, which come off the slow lines at Surbiton (or vice versa on the Down) would stay on the less utilised Slows, possibly along with a two per hour Haslemere stopper.

Essentially you could then have on the Fast lines 14 trains per hour (outside of the peaks): -

• 2 per hour Weymouth - Waterloo [Fast]
• 2 per hour Poole - Waterloo [Semi-fast]
• 2 per hour Portsmouth (via Eastleigh) - Waterloo [Semi-fast]
• 2 per hour Portsmouth (via Guildford) - Waterloo [Fast]
• 2 per hour Portsmouth (via Guildford) - Waterloo [Semi-fast]
• 2 per hour Exeter - Waterloo [Fast]
• 2 per hour Yeovil/Gillingham - Waterloo [extended back Salisbury stoppers - Semi-fast]

Winchester could then have six trains per hour to Waterloo.

I don't want to appear critical if something that is just a "here's something as we don't really have any idea as to what the future may hold", however a doubling of paths required for services through Salisbury could appear to be excessive.

An alternative, which may solve other problems and I'll spell them out below, would be to have 3 WofE trains (1 new path) and provide the extra capacity/speed up the WofE services by extending the Basingstoke stoppers to Salisbury.

The main reason is that by having the Basingstoke stoppers continue in service beyond Basingstoke is that you increase platform capacity. As by the time you so the train, everyone gets of the train is checked, it departs it then returns, it sits at the platform and the guys again you could have run three services through the station. Which could be a limitation in the future. It also means that the crossing from one direction to the other happens on a much quieter section of track, which could further reduce the capacity impact of these services.

On the WofE line, the advantages would be that the minor stations could see at least 3tph (1 WofE service and 2 or more Basingstoke stoppers, depending on if they see an increase in frequency) with the WofE services calling on a skip stop pattern other than one very fast service (which could even just call at Basingstoke, Salisbury and Yeovil before stopping at most stations to Exeter).

In doing so there is a much better service between all the stations on the line (at least 3tph, with Andover having at least 4tph and Salisbury having at least 5tph).

Yes, no one is going to go to London on the Basingstoke stoppers from Salisbury, but they won't need to. The point is that you free up platform capacity at Basingstoke and potentially move a lot of the local passengers off of the faster services, which could help with station dwell times. For instance, why try and get off a busy train at Basingstoke, when there are other services (which could even get you there at a better time or allow you to leave home a bit later, but may take 5 minutes longer) which are less busy and you are guaranteed a seat (if not 2).

It could also save the TOC money to run, as rather than having one train all the way from Waterloo (4 sets of units for 1tph) you only need the extra units from Basingstoke (up to 4 sets if units for 2tph). However, given that the current Basingstoke stoppers arrive about 27 minutes before they do the return journey and there would be a pause at Salisbury for about 20 minutes, there could be scope to reduce the dwell time at the end of the route so as to reduce the number of units needed.

In which case, you could require just 3 sets of units to run a possible more frequent Basingstoke stoppers (3tph) service to Salisbury.

Of course, with a complete recast of the timetable anything could happen.

 

[MarkyT]

An alternative, which may solve other problems and I'll spell them out below, would be to have 3 WofE trains (1 new path) and provide the extra capacity/speed up the WofE services by extending the Basingstoke stoppers to Salisbury.

Perhaps better to send the Basingstoke local terminators to Micheldever to reverse and minimise crossover conflict and platform occupancy. That is at least already electrified, and with the outside fast lines bypassing the platforms proposed in the Wessex route study the trains could use either face of the existing central island to reverse, or an additional bay stub track could be built 'Woking style' at the London end.

 

[The Ham]

Perhaps better to send the Basingstoke local terminators to Micheldever to reverse and minimise crossover conflict and platform occupancy. That is at least already electrified, and with the outside fast lines bypassing the platforms proposed in the Wessex route study the trains could use either face of the existing central island to reverse, or an additional bay stub track could be built 'Woking style' at the London end.

Under the current extent of electrification I would agree, however it is likely that after 2030 (the opening of Crossrail 2 is expected to be 2030) that the line to Salisbury will have wires.

Given the number of services that use the line between Basingstoke and Micheldever it is unlikely that there would be sufficient capacity to run more services that way as well as all the extra services running to the south coast, whilst towards Salisbury could have 6 passenger services (3 WofE & 3 Basingstoke stoppers extended) and a few freight an hour (say up to 10tph total services) which should be fairly easy to accommodate on a double track railway.

 

[swt_passenger]

There's nothing in the Wessex Route Study that explicitly suggests increasing frequency to Exeter or anywhere beyond Salisbury. It seems to fall under the heading of too far into the future to be discussed yet.

 

[Muzer]

Extend the Basingstoke stoppers to Salisbury because of platform capacity at Basingstoke? What about platform capacity at Salisbury? Pretty sure it won't handle another 2tph terminators, given the existing services and restrictive layout...

 

[swt_passenger]

Extend the Basingstoke stoppers to Salisbury because of platform capacity at Basingstoke? What about platform capacity at Salisbury? Pretty sure it won't handle another 2tph terminators, given the existing services and restrictive layout...

You'd presumably re-open P1 for through trains and terminate on the island? All depends how much emphasis is placed on existing cross platform or same platform interchange

 

[Ianno87]

Winchester is only a 2 platform station and, given a 3 minute gap between services, such as platforms 8 and 9 at Clapham*, often having one train every three minutes when the slow platforms are OOU. This means it can have 20 trains each way per hour. But saying that, it would cause a bottleneck on Basingstoke, Shawford, swaythling and St. Denys.
Eastleigh has a 4 track station so it wouldn't have much interference.

Just a thought :3

20tph - only if every train is exactly the same!

Killer on this section are freight paths, particularly northbound (which is uphill), which knock out some capacity as they are much slower than a 100mph passenger train.

Then there are the trains that call at Micheldever/Shawford which knock out some more capacity...

And then you need to figure out what to do with all these trains when they get to Eastleigh - particularly on the two tracks from there to Southampton, including the tunnel (and where they all turn back)

 

[swt_passenger]

And then you need to figure out what to do with all these trains when they get to Eastleigh - particularly on the two tracks from there to Southampton, including the tunnel (and where they all turn back)

Exactly - and also allow for the five tph each way that join the route within that area, four each way from the Netley line, and the Romsey rounder, and ECS, and freight that runs to and from Eastleigh via Romsey, etc etc... I noted earlier Winchester's overall frequency is constrained by all the other passenger routes when looking towards London, but is also very much constrained westbound as well.

 

[Coolzac]

There's nothing in the Wessex Route Study that explicitly suggests increasing frequency to Exeter or anywhere beyond Salisbury. It seems to fall under the heading of too far into the future to be discussed yet.

I read that and was disappointed. Given that I would consider it a mainline and the growth of commuting into Exeter, I wish it was in future plans!

 

[Muzer]

You'd presumably re-open P1 for through trains and terminate on the island? All depends how much emphasis is placed on existing cross platform or same platform interchange

This is currently used as the depot reception road though. I'm not entirely sure how feasible reopening it would be because of this.

 

[swt_passenger]

This is currently used as the depot reception road though. I'm not entirely sure how feasible reopening it would be because of this.

It has already been proposed for reopening in previous studies though, so they must have had a planned work round for that?

--- old post above --- --- new post below ---

I read that and was disappointed. Given that I would consider it a mainline and the growth of commuting into Exeter, I wish it was in future plans!

But there are already plans to double frequency between Exeter and Axminster (or Honiton where paths are unavailable) for Exeter commuting. I was thinking more about the earlier ideas to run more trains all the way to Waterloo...

 

[Coolzac]

It has already been proposed for reopening in previous studies though, so they must have had a planned work round for that?

--- old post above --- --- new post below ---



But there are already plans to double frequency between Exeter and Axminster (or Honiton where paths are unavailable) for Exeter commuting. I was thinking more about the earlier ideas to run more trains all the way to Waterloo...

Oh good! I didn't know that. That's a stepping stone at least!

 

[swt_passenger]

Oh good! I didn't know that. That's a stepping stone at least!

There are known dates for Devon Metro service introduction in the GW Direct Award franchise agreement (from December 2018 for phase 2 to Axminster), but this is getting a bit off-topic for this thread.

 

[Hammy1966]

Very interesting perspectives. Thank you all. So if something needed to be done in the short term and it can't be train frequency. Is it number of carriages and extending the so called "peak hour earlier in morning later in evening. And offer a ticket price incentive for not travelling at the peak hour??