Crossrail 2 Swirl-Max - relieving the Northern Line

Crossrail 2 Swirl is a plan to take Crossrail 2 via Earlsfield, not Balham. The big issue with Swirl is that it does not directly relieve the Northern Line. This article provides a way to achieve that - "Swirl-Max".

How can Swirl be enhanced to relieve the Northern Line?

The Swirl plan deliberately takes Crossrail 2 away from the Northern Line. This is because any shared station (Balham or Tooting Broadway) on the main Crossrail 2 line allows passengers from places as diverse as Chessington, Kingston, Shepperton and Epsom to change onto the Northern Line, as well as for passengers to change from the Northern to Crossrail 2. My research suggests that the movement from Crossrail 2 to Northern will not be insignificant, and as such, it is far from clear that Crossrail 2 will make the Northern line less overcrowded. See my full analysis.

It is the case that simply by being built, Crossrail 2 will attract some journeys away from the Northern. This will notably be the case for residents around South Wimbledon. However, it is accepted that the Swirl plan alone would make little difference to Northern Line crowding.

Initially, it seemed that the best way to relieve the Northern Line would be to extend the Northern Line (West End Branch) from Battersea Power to Clapham South and/or Balham. However, the journey time analysis showed that such an approach would not achieve its goals, at least in part because the Northern Line Extension to Battersea Power does not interchange with the Victoria Line. As such, my view is that the best option is a branch of Crossrail 2 to relieve the Northern Line.

Swirl-Max - relieving the Northern Line

The Swirl-Max plan is an extension of the Swirl plan, proposing a branch of Crossrail 2 to relieve the Northern Line.

The branch would split from the main Crossrail 2 route south of Clapham Junction. It would then proceed to Balham, using a station alignment next to the existing station (the road between the station and Sainsburys). From there, it is proposed to take the branch on to Streatham.

Once the branch reaches Streatham, it makes sense to bring it to the surface to take over the existing line (coloured orange on the map) through Tooting (mainline) and Haydons Road to Wimbledon, where the branch would terminate. An additional station would be provided on the A24 near Tooting St.Georges hospital. The key benefit of doing this is that both Balham and Tooting on the Northern Line are relieved - it is no longer a choice of one or the other.

Note that all services from Chessington, Epsom, Kingston and Hampton Court would run via Earlsfield. The layout of the tracks at Wimbledon would make it impossible for those services to run via Streatham.

The branch would have 10tph (trains per hour), one every 6 minutes. While it may seem slightly low, this frequency does not turn out to be a problem for the branch. While relatively few people will change from the Northern Line to Crossrail 2 at Balham, my journey time analysis suggests that the numbers who would change with TfL's scheme are not as great as might be imagined. Thus, the key to relieving the Northern Line is attracting enough people to start their journey on Crossrail 2, rather than on the Northern. The Swirl-Max plan does this by providing four stations near the Northern Line - Balham, Tooting, St.Georges and Haydons Road. All four would provide competitive journey times to the West End, and considerably more comfort.

Details

It is proposed that the 10tph currently proposed to terminate at Wimbledon would run via the Streatham branch. The key purpose of the 10tph TfL want to terminate at Wimbledon is to provide performance management for the core Central London section of Crossrail 2. As such, it is vital that the branch be able to perform the same role.

To ensure reliable performance, the branch would need to have two specific characteristics. Firstly, the branch must be completely isolated from Network Rail. Secondly, the branch must have overhead electrification (to avoid any problems due to changing from overhead to third rail power supply). When considering possible branches, these two characteristics were key.

The proposed branch is in tunnel from Clapham Junction to Streatham. South of Streatham, the branch would surface and completely take over the line from Streatham to Wimbledon, without sharing any track between Streatham and the junction for Tooting. The existing Thameslink services on that line would be diverted to run via Sutton to Wimbledon, effectively doubling the service between Sutton and Wimbledon.

The Tooting Broadway station saga has indicated that there is some tricky geology in the area. To mitigate this, it is proposed to build top-down station boxes at both Balham and Streatham. This should keep the stations within the band of London Clay.

At Wimbledon, it is proposed that platform 10 would be used for the Thameslink service from Sutton, and platform 9 for the Swirl-Max Crossrail 2 branch service via Streatham. Terminating 10tph in a single platform is not desirable, however it is feasible. It should be possible to provide an additional platform 11 in the area of the Queens Road car park to mitigate this. There is the potential to extend platform 10 south under the existing deck to provide more space. Furthermore, it is expected that an additional turn-back location would be provided somewhere along the branch. It is intended that at least a single track would be provided between platform 10 and the Weir Road depot for empty stock movements.

The proposed tunnel portal site is at, or near, Wandsworth Prison. While it is not yet certain that the prison will be closed, it must be considered at least possible. That site has reasonable road access via the A214, however it is assumed that most spoil would be sent down the main running tunnel to the New Malden portal. As such, tunnelling for the branch would begin later than that for the main line. If the prison does not close, the nearby car parks and nursery offer sufficient space for the worksite.

If the prison site does become available, it may be possible to move the "tunnel swap" location of the Swirl plan to the north of Earlsfield, near the prison. Doing so could save £300m by avoiding the need for a new sub-surface Earlsfield station.

While not essential, it is considered desirable to provide at least passive provision for four platforms at Clapham Junction. Doing so, could allow the branch to be separated from Crossrail 2 at some future point in time.

When deciding on the plan above, some other options were rejected. A one station branch to Balham or a two station branch to Balham and Streatham Hill would not attract enough traffic off the Northern Line. A route via Streatham Hill to Streatham would add to journey time and costs, plus be complicated to build (no easy way to create a tunnelled station at Streatham Hill. A branch with a tunnelled station at Tooting Broadway would run into the same geological problems that caused TfL to move to Balham.

Benefits

The Swirl-Max plan has the same benefits as the Swirl plan, plus these additional benefits:

• Northern Line relief at both Balham and Tooting
• Ability to provide a station on the doorstep of St.Georges hospital
• No risk of overloading the Northern Line with passengers from beyond Wimbledon
• Significantly faster and more frequent service to Streatham
• Doubles the Thameslink service between Streatham and Sutton, and Sutton and Wimbledon

See also the full journey time analysis. For example, Streatham to Tottenham Court Road on Oxford Street would take just 15 minutes, with a train every 6 minutes.

It is difficult to quantify the potential Northern Line relief. However, if the four stations Haydons Road, St.Georges, Tooting and Balham could capture 35% of the traffic from the Northern Line at Colliers Wood, Tooting Broadway and Balham then around 1 in 4 people would be removed from the Northern Line north of Balham.

In addition, Swirl-Max provides far greater Victoria Line relief than the TfL scheme. This occurs, because many people that currently take the bus from Streathan to Brixton would instead take Crossrail 2 at Streatham.

My calculations suggest that this plan does not require a shaft on Wandsworth Common. This is because the proposed route is more direct to Balham. As such, a shaft at the prison site would suffice between Clapham Junction and Balham.

Costs

The following is a rough cost estimate for the Swirl-Max plan:

• Balham station - £300m
• Streatham station - £300m
• Additional tunnelling - £600m
• Surface works to take over line via Haydons Road - £300m
• Additional items / contingency - £500m

This comes to a total of £2bn. But it is important to remember that this is a high level estimate.

Potentially this means that the Swirl-Max plan is more expensive than TfL's current plan taking Crossrail 2 via Balham. However, it seems reasonable to suggest that Swirl-Max provides better transport benefits and greater reach for economic growth. A formal economic analysis would be needed to confirm this however.

While it is possible to end the branch at Streatham, it would seem that doing so misses the potential Northern Line relief from the Tooting and St.Georges stations. The additional cost to reach Wimbledon from Streatham should be easy to offset against the additional benefits.

Summary

The Swirl-Max plan for Crossrail 2 extends the Swirl plan, providing a branch from Clapham Junction to Balham, Streatham and Tooting. Instead of the question being "Balham or Tooting", it can be "Balham and Tooting, oh and Earlsfield and Streatham too!".

Feel free to comment to ask questions or support the plan.

Fewer trains at Earlsfield with Crossrail 2

Planning for Crossrail 2 is underway with a consultation currently open. The consultation invites feedback on "Proposed service patterns", yet most people in Earlsfield appear blissfully ignorant of what Crossrail 2 means to them. This article aims to make it clear.

Crossrail 2

The South West Main Line (SWML) from Waterloo through Earlsfield to Woking and beyond is one of the busiest railway lines in the country. It consists of 4 tracks all the way from Woking to Waterloo, with services from Earlsfield on the two slow lines.

Since the 4 tracks are no longer sufficient for demand, Transport for London and Network Rail are planning to add an additional 2 tracks between New Malden and Clapham Junction, as part of Crossrail 2. The following map shows the official plan:

The current services that serve Earlsfield today, from Kingston, Hampton Court, Chessington and Epsom will be diverted onto Crossrail 2 and run via Balham, not Earlsfield.

Given this, a key question arises - What services will stop at Earlsfield once Crossrail 2 opens? The answer to this question is not good news for Earlsfield.

Earlsfield is likely to have around 40% fewer trains once Crossrail 2 opens

Exact details are unclear, partly because they are not yet decided. However, the consultation documents and verbal conversations with Network Rail indicate that the following is the working hypothesis (tph = trains per hour):

• Before Crossrail 2 opens - 18tph stop at Earlsfield
• After Crossrail 2 opens - 10-12tph stop at Earlsfield (a cut of between 33% and 44%)

What this means in practice is that 6-8tph will run through the platforms at Earlsfield without stopping. These will be the current fast services from Surbiton, which will be moved off the fast lines to make space for more trains from beyond Woking.

Transport for London and Network Rail believe that although there would be fewer trains stopping at Earlsfield, those that did stop would have more space available. As such, they argue that this service cut is not a major problem.

Ultimately, it is up to the residents of Earlsfield to decide whether they want to fight for a better deal.

Crossrail 2 Swirl

This blog is promoting a change to Crossrail 2, the Swirl plan. Swirl proposes routing Crossrail 2 via Earlsfield instead of Balham.

Were Swirl to be adopted, the service at Earlsfield would potentially increase to 30tph, one train every two minutes. It would also see Earlsfield added to the tube map, which experience suggests is very positive for an area.

If you live in Earlsfield you may not realise that the potential exists to get your area a much better deal. The difference between 10tph and 30tph is stark, as is the potential to be on the tube map.

Have a read of the Swirl plan, and if you agree, please respond to the consultation mentioning "Crossrail 2 Swirl".

Update 2016-01-19: See also the Swirl-Max plan which services Earsfield, Balham, Streatham and Tooting providing much greater benefits to the area.

Crossrail 2 and Surbiton

Planning for Crossrail 2 is underway with a consultation currently open. The consultation invites feedback on the following topics:

• Station locations, entrances and exits
• Shaft locations for the tunnelled section of the scheme
• The construction sites required to build and operate the tunnelled section of the scheme
• Proposed service patterns

The last of these is of most relevance to Surbiton.

While this article is focussed on Surbiton, much of the logic applies to other stations - Esher, Hersham, Walton, Weybridge, Byfleet and West Byfleet.

Crossrail 2

The South West Main Line (SWML) from Waterloo through Surbiton to Woking and beyond is one of the busiest railway lines in the country. It consists of 4 tracks all the way from Woking to Waterloo, with 5 tracks available for services on the final Waterloo approach. The 4 tracks consist of two pairs - the slow lines and the fast lines. Unfortunately, 4 tracks are no longer sufficient for the demand.

For Network Rail, the key purpose of Crossrail 2 is to provide an additional 2 tracks from New Malden to London, creating a 6 track railway. Current plans have this as 6 tracks on the surface between New Malden and Wimbledon, where the additional 2 tracks descend into tunnel for the rest of the route to London.

For Transport for London (TfL), the key purpose of Crossrail 2 is different. They need the new line to relieve the underground network, specifically the Victoria Line and Northern Line. As such, Crossrail 2 is planned to route via Balham (on the Northern Line) and then on to Victoria, Tottenham Court Road and Euston. This means that Crossrail 2 is not currently planning to serve Earlsfield.

The current consultation is the first step in deciding which train services run once Crossrail 2 opens and there are 6 tracks available from New Malden.

Current peak services

Currently, Surbiton has the following peak services:

• 07:01 - 29mins - from Hampton Court (all stations to Waterloo)
• 07:08 - 16mins - from Woking (non-stop to Waterloo)
• 07:11 - 25mins - from Guildford via Claygate (fast to Wimbledon, then all stations to Waterloo)
• 07:27 - 20mins - from Woking (non-stop to Waterloo)
• 07:31 - 31mins - from Hampton Court (all stations to Waterloo)
• 07:38 - 16mins - from Woking (non-stop to Waterloo)
• 07:41 - 28mins - from Guildford via Claygate (New Malden, Wimbledon, then all stations to Waterloo)
• 07:53 - 18mins - from Guildford via Claygate (non-stop to Waterloo)
• 07:57 - 20mins - from Woking (non-stop to Waterloo)
• 08:01 - 30mins - from Hampton Court (all stations to Waterloo)
• 08:08 - 16mins - from West Byfleet (non-stop to Waterloo)
• 08:11 - 27mins - from Guildford via Claygate (New Malden, Wimbledon, then all stations to Waterloo)
• 08:19 - 15mins - from Woking (non-stop to Waterloo)
• 08:25 - 19mins - from Woking (non-stop to Waterloo)
• 08:31 - 30mins - from Hampton Court (all stations to Waterloo)
• 08:38 - 19mins - from Farnham (non-stop to Waterloo)
• 08:42 - 17mins - from Guildford via Claygate (non-stop to Waterloo)
• 08:48 - 16mins - from Woking (non-stop to Waterloo)
• 08:57 - 25mins - from Guildford via Claygate (fast to Wimbledon, then all stations to Waterloo)

The lines in bold are the fast services, "Surbiton Express", which currently run non-stop from Surbiton to Waterloo.

In the authors opinion, the Surbiton Express trains are unlikely to survive after Crossrail 2.

Network Rail planners have a tough job. There are simply too few train paths available into Waterloo for the number of people wanting to travel. Unlike some other routes into London, practically every train in the peak is at the maximum length. In addition, ideas such as double decker trains, or even longer trains, are impractical. (Better signalling may be an option, however at present Network Rail has limited experience in running any line with more than 24 train paths an hour.)

Faced with increasing demand and fixed paths into London, Network Rail simply has to allocate trains as best it can. The most efficient way to do this is to use the two fast lines from Woking to Waterloo solely for trains running non-stop from Woking to Waterloo. The effect of that is that all trains to Surbiton would run on the slow lines, not the fast lines. As such, the Surbiton Express trains would almost certainly cease to exist in their present form.

As it turns out, removing the 5 Surbiton Express trains (per hour) probably yields more than 5 extra train paths from Woking to Waterloo. This is because there is no need to provide space in the timetable for lateness at the junction at Surbiton. This fact emphasises why the Surbiton Expresses are seen as poor use of the limited train paths.

While these changes could happen prior to Crossrail 2 opening, the new line offers the best chance to mitigate the loss of the Surbiton Expresses. This is because the existing slow services to Shepperton, Chessington, Hampton Court and Epsom move off the slow lines and onto the additional Crossrail 2 tracks. This leaves the existing slow lines free to handle traffic from Surbiton.

Peak services with Crossrail 2

The consultation leaflet for Crossrail 2 proposes the following services with Crossrail 2 (tph = trains per hour):

• 4tph Surbiton to Crossrail 2 - from Hampton Court, all stations including Berrylands and New Malden
• 8tph Surbiton to Waterloo - no information provided on stopping patterns

The key question for Surbiton is what will the stopping pattern be of the 8 peak trains to Waterloo? As it turns out, some clues are buried in other parts of the consultation:

• 4tph New Malden to Waterloo - but these are services from Kingston, not Surbiton
• 8tph Raynes Park to Waterloo - but these are services from Kingston and Epsom, not Surbiton

Thus, none of the trains from Surbiton to Waterloo are expected to stop at New Malden or Raynes Park. (The Crossrail 2 trains from Hampton Court via Surbiton will provide the connection to New Malden and Raynes Park.)

Verbal conversations at consultation events have indicated that the current plan is for 10-12tph to Waterloo from Wimbledon and the same at Earlsfield. Thus it can be seen that 8tph of the 10-12tph at Wimbledon and Earlsfield stop at Raynes Park, with only 2-4tph from Surbiton expected to stop at Wimbledon and Earlsfield. The simplest timetable for Surbition would therefore be:

• 4tph Surbiton to Crossrail 2 - from Hampton Court, all stations including Berrylands and New Malden
• 4tph Surbiton to Waterloo - stopping at Wimbledon, Earlsfield, Clapham Junction and Vauxhall
• 4tph Surbiton to Waterloo - stopping at Clapham Junction and Vauxhall

It is important to emphasise that this is speculation by the author based on the available facts.

To drill down further, see these unofficial journey time estimates. To summarize, I'd estimate journey times of 23 to 26 minutes from Surbiton to Waterloo once Crossrail 2 opens, and 25 minutes from Surbiton to Victoria.

The reason for the relatively slow journey times is that all trains from Surbiton will be on the current slow lines. The slow lines need to serve Earlsfield and Vauxhall, and there is no possibility to overtake the stopping train in front, thus missing out stations saves relatively little time.

Additional data

Updated 2016-01-10.

These are some additional points that provide evidence for the impact on Surbiton.

1) The speed limit on the slow lines is less than that on the fast lines. This can be found in the Network Rail Sectional Appendix.

2) The slow lines run into the low numbered platforms at Waterloo. These can only take 8 car trains today, and are only planned to be extended to 10 car trains. As such, without an additional investment, services from Surbiton will be limited to 10 cars.

Alternate Crossrail 2 plan - Swirl

This blog is also promoting a change to Crossrail 2, the Swirl plan. Swirl proposes routing Crossrail 2 via Earlsfield instead of Balham.

If the Swirl plan happens, then journey times from Surbiton would have the potential to be 1 to 2 minutes shorter. This is because no train on the slow lines would be responsible for stopping at at Earlsfield, allowing trains to run slightly faster. Note however, that the Swirl plan would need widespread support from the public to be adopted.

Summary

The Surbiton Express trains are on borrowed time. They will probably end when Crossrail 2 starts, but they just might reduce in number before that.

Comments welcome, but make sure to respond to the official consultation.

Crossrail 2 Journey time modelling

TfL have not made public their modelling for Crossrail 2. As such, I've done some journey time modelling myself.

Journey time modelling

Journey time modelling is a hard problem in general, as there are many possible routes to consider on a network like that in London. However, if the problem is simplified to only include a subset of routes, it is possible to obtain an answer.

The simplifications used are:

• Only journeys from SWML destinations affected by Crossrail 2 are considered
• Only journeys to central London destinations are considered
• Interchange times are estimated
• A maximum of three trains is allowed to get from start point to destination
• Buses are ignored
• Trams are ignored
• Walking is ignored
• Time to enter/exit stations is ignored

Even with these simplifications, it is possible to get some reasonable figures out, and take a look at two key questions:

• Will Northern Line passengers change onto Crossrail 2?
• Will Crossrail 2 passengers change onto the Northern Line?

The results are here:

• Crossrail 2 via Balham (TfL plan)
• Crossrail 2 via Tooting Broadway (TfL old plan)
• Crossrail 2 via Earlsfield (Swirl plan)
• Crossrail 2 via Earlsfield with branch to Balham/Streatham/Tooting (Swirl-Max plan)

Each page contains a set of possible options for each of a long list of possible journeys. A key of station codes is given at the bottom of each page.

The first finding matches that of my previous article. Journey times from Crossrail 2 suburbs to London Bridge and Bank are quickest by changing onto the Northern Line.

The second finding was unexpected however. The figures for Balham indicate that many passengers travelling from Morden to Victoria and Euston will not change to Crossrail 2! This is because the time saved by the new route is not enough of a saving over the existing route (changing to the Victoria line at Stockwell).

Finally, it is important to remember that the time to enter and exit the station is not included. This can have a big impact together with the walking distance to an individual's actual start and end point.

Summary

This quick post provides links to journey time analysis for Crossrail 2 in South West London. The analysis is imperfect, but enough to raise further concerns about TfL's Balham option.

Crossrail 2 Swirl

This article outlines Crossrail 2 Swirl, an alternative to the flawed "Balham Bulge" plan put forward by TfL (Transport for London) in South West London. As we'll see, Swirl is both cheaper and more effective than TfL's plan.

Update 2015-12-10: This article is effectively part 1 of 2. The Swirl plan below proposes a fast line tunnel under Wimbledon. The Swirl-Max plan proposes how Swirl can be extended to serve Balham, Tooting and Streatham. See also my previous articles on Crossrail 2. And follow up on journey times.

TfL plans for Crossrail 2

This map outlines the current TfL plan for Crossrail 2 between Clapham Junction and Wimbledon, via Balham.

As can be seen, the "Balham Bulge" route from Wimbledon to Clapham Junction via Balham is very indirect. In addition, the chosen tunnel portal site to the north east of Wimbledon, requires the demolition of most of Wimbledon town centre, including the Centre Court shopping centre (everything along the purple line on the map is demolished). The Swirl plan removes the ineffective Balham Bulge and avoids the need to demolish Wimbledon town centre.

For more details on why a Balham routing will not be effective, see the previous article on how TfL's plans make the Northern Line overcrowding worse not better.

Crossrail 2 Swirl

Crossrail 2 Swirl is a proposal to alter the route and design of Crossrail 2 between Clapham Junction and Wimbledon. Instead of serving Balham or Tooting, Swirl serves Earlsfield, hence the name - "SW EARLsfield".

To provide the total capacity increase needed for South West London, Surrey and Hampshire, a total six tracks are needed from at least New Malden to Clapham Junction. To provide this, Swirl proposes a tunnel from the A3 between New Malden and Raynes Park all the way to Clapham Junction and beyond, giving four tracks on the surface and two tracks in tunnel. Between the junction at New Malden and the A3 tunnel portal, six tracks would be provided by removing the fast line platforms at New Malden.

The A3 tunnel portal site has a key advantage over TfL's Gap Road site in that it has excellent road access. Being able to send heavy vehicles down the A3 to the M25 will have major benefits for local roads.

All fast line services from Surrey, Hampshire and beyond would run via the new tunnel under New Malden, Raynes Park and Wimbledon. No underground stations are needed on this section as these are the fast lines. The existing four tracks through Raynes Park on the surface would be used for Crossrail 2 and outer suburban services to Waterloo.

At Wimbledon, the existing six platforms would be retained. A new footbridge would be needed to cope with increased usage, but the rest of the town centre would be completely unaffected. Crossrail 2 trains would use the existing slow line platforms. The outer suburban services to Waterloo would use the existing fast line platforms, providing a cross-platform interchange. This will allow passengers to change to a high frequency Waterloo service (TfL proposes an interchange to a much lower frequency Waterloo service).

In order to provide a high frequency service through the core of Crossrail 2, it is necessary to turn back some trains at Wimbledon. This would be achieved using the existing Thameslink platforms, with the tram evicted to run at street level. Thameslink services would share the platforms.

The key part of the Swirl proposal is the very large Weir Road industrial site between Wimbledon and Earlsfield. This would be used to "swap" usage of the tunnel. The fast tracks would be taken out of the tunnel and back to the surface to use the existing surface tracks to Clapham Junction. The same site would also be used to take the Crossrail 2 tracks down into the tunnel. As a result, Earlsfield station would be replaced with a sub-surface station.

Note that the proposal is for a single tunnel all the way from New Malden to beyond Clapham Junction using a single Tunnel Boring Machine (TBM). While this may seem strange, the costs associated with tunnelling tend to be at the tunnel portals, with the distance that the tunnel is driven being a secondary consideration. As such, it is cheaper to have a single TBM rather than two separate tunnels. The "swap" at Weir Road involves a relatively simple cut and cover box that would be built after the TBM had passed through the site.

The Crossrail 2 Swirl proposal has minimal impact on the branches that can be served by Crossrail 2 in outer London. As such, the map of services below shows the same branches as TfL's official scheme:

However, unlike the TfL scheme, none of the outer suburban (green) services need to stop at Earlsfield or Raynes Park, providing a faster journey for many passengers. It should be noted that only those outer suburban services to Twickenham would stop at new Malden.

Benefits

The Swirl proposal has the following benefits compared to the TfL plan:

• £1.5bn cheaper (estimated)
• Much better service for Earlsfield
• Better services to Surrey, Hampshire and beyond
• No need to demolish the entire centre of Wimbledon
• Tunnel portal with direct access to the A3 for lorry traffic
• Does not worsen the overcrowding on the Northern Line

The cost estimate is very rough, but there is no doubt that Swirl has a lower cost than TfL's plan. The total length of tunnel from New Malden to Clapham Junction is just 1km longer than the indirect tunnel from Wimbledon to Clapham Junction via Balham. This has an extra cost of about £100m. The sub-surface station at Earlsfield should be cheaper to build than the tunnelled station proposed for Balham, saving perhaps £100m. The tunnel "swap" is again a relatively simple construction, perhaps £200m. The primary difference is therefore is the large amount of work avoided at Wimbledon.

At Wimbledon, TfL is currently planning on demolishing the entire town centre. The main covered shopping mall, Centre Court, and many more buildings would be demolished to allow an additional four platforms to be built along with a long cut and cover box. The disruption caused will be immense. It is very hard to estimate the cost of this work, however £2bn does not seem like an unreasonable estimate. By contrast, Swirl requires minor changes to the existing station, plus some new tram tracks, for a far lower cost.

The Swirl plan provides better services to outer suburban services such as Surbiton, Claygate, Walton and Guildford. This comes from the ability to provide more services now that the outer suburban trains do not need to serve Earlsfield. These services will also save time without the need to stop at Earlsfield.

Swirl provides a better service to long distance services from places such as Portsmouth, Basingstoke, Winchester and Southampton. The benefit here is that the fast services will run via the new tunnel between New Malden and Earlsfield. The new tunnel will have a higher speed limit than the existing fast tracks on the surface. As such there would be a small journey time saving (which cost-benefit calculations tend to place a high benefit value on).

At Earlsfield, the new sub-surface station can be constructed south of the existing station and double ended (two exits, one at each end). This would provide an exit from the station to the far end of the Weir Road site. Assuming that the Weir Road site is still used for a train depot, there is no reason why the depot cannot be covered with a concrete deck. This allows the site to be used for massive development, with enhanced value thanks to the new station entrance/exit.

Additional notes

Update 2015-11-29: This section was added to provide some additional notes on Swirl primarily for TfL and Network Rail.

Swirl proposes the "tunnel swap" occurs at the Weir Road site. This is because it is known that the site is large enough at 1km long. However, there would be cost benefits to perform the swap north of Earlsfield alongside the cemetery. This is a much narrower site however. If the prison becomes available for redevelopment, it may be possible to use that site to make this alternate swap location more practical.

Swirl proposes the tunnel portal next to the A3 at New Malden. This is good for road access, but not the easiest in construction terms. The next possible portal site is north-east of Berrylands station, on the east side of the river north of some housing. That site has less good road access, but is completely off the railway, potentially making it easier to construct. A proper engineering analysis would be needed to compare the two sites.

Swirl has two elements - a fast line tunnel under Wimbledon and serving Earlsfield instead of Balham. It should be noted that the fast line tunnel part of Swirl is compatible with serving Balham, although the author does not believe that to be the best approach.

Relieving the Northern Line

Update 2015-12-10: Since serving the Northern Line is critical to Crossrail 2, the Swirl plan has been extended into the Swirl-Max plan, which serves Earlsfield, Balham, Tooting and Streatham. Swirl-Max is the version to be submitted to the TfL consultation.

Originally, this article proposed that the Northern Line could be relieved by extending the Northern Line Extension (West End branch) from Battersea Power station to Cedars Road on the Clapham/Battersea border and on to Clapham South and/or Balham. This option has now been dropped as further analysis showed it would not work.

Summary

Crossrail 2 Swirl is a detailed plan to provide a better solution for South West London, Surrey and Hampshire. It proposes a single tunnel from New Malden to Clapham Junction and beyond, with a tunnel "swap" between Wimbledon and Earlsfield. This avoids the need to destroy Wimbledon town centre, and saves around £1.5bn in the process. See the Swirl-Max plan for how Balham and Tooting would be served.

The October 2015 consultation is now closed, but readers are encouraged to continue to speak to politicians and others in power to fight for a better option for Crossrail 2. Use the term "Fast Line Tunnel" or "Crossrail 2 Swirl".

Crossrail 2 and the Northern Line

TfL's plans for Crossrail 2 have always included a connection to the Northern line between Clapham Junction and Wimbledon. This blog has long argued that this is a mistake. Here is the detailed explanation as to why.

Update 9 Feb 2016 - The final article in the series, Crossrail 2 Swirl-Max - is now published.

Update 12 Nov 2015 - The next article in the series, Crossrail 2 Swirl - is now published.

Update 15 Nov 2015 - A full analysis of journey times is now complete:
Journey times with CR2 station at Balham (the TfL plan)
Journey times with CR2 station at Tooting Broadway
Journey times with CR2 station at Earlsfield (the Swirl plan)
Journey times with CR2 station at Earlsfield and branch to Balham/Streatham/Tooting (the Swirl-Max plan)

Crossrail 2 and the Northern Line

Until October 2015, the TfL plan was to take Crossrail 2 between Clapham Junction and Wimbledon via Tooting Broadway to link with the Northern line. In the October 2015 consultation, Balham is proposed instead of Tooting Broadway:

The stated purpose of the Northern Line connection on Crossrail 2 is:

A Crossrail 2 station at Balham would still provide very similar benefits to one at Tooting Broadway, principally helping relieve crowding on the most congested parts of the Northern line.

As can be seen, the pressure is to provide additional capacity for the Northern Line. Already today, it is very difficult to get on a northbound Northern Line train at any of the three Clapham stations in the morning peak. The Crossrail 2 station is supposed to help alleviate this.

Unfortunately, Crossrail 2 could well make the Northern Line crush worse not better.

The Capacity Difference

Each Crossrail 2 train will have a capacity of around 1500 people (10 car trains of mainline size). Each Northern Line train has a capacity of around 665 people (6 car trains of tube size). Thus, each Crossrail 2 train will have around 2.25 times the capacity of each Northern Line train.

Both services, Crossrail 2 and the Northern Line will run at around 30tph (trains per hour). Thus, the capacity difference between the two lines is fixed around 2.25.

If 1 in 6 people on a Northern Line train transfer to Crossrail 2 then that is about 110 people. But if 1 in 6 people on Crossrail 2 transfer to the Northern Line, that is around 250 people. As should be immediately obvious, relief of the Northern Line only happens if more people transfer from Northern to Crossrail 2 than the other way around.

Put another way, a transfer of 1 in 6 people from the Northern Line train to Crossrail 2 is equivalent to a transfer of 1 in 15 people from Crossrail 2 to the Northern Line. But who will transfer and why?

The Journey Time problem

To determine who will transfer, it is necessary to look at the journey times.

From Balham to Moorgate is 23 minutes by Northern Line. The same journey using Crossrail (taking Crossrail 2 to Tottenham Court Road and changing to Crossrail 1) would take roughly 22 minutes (13 minutes to Tottenham Court Road, 4 minutes to change and 5 minutes to reach Moorgate). Thus, Crossrail offers a very small 1 minute saving and the risk involved in a change of trains.

From Balham to Bank station is 21 minutes by Northern Line. By Crossrail it would be 28 minutes changing at Victoria to the District Line or Angel to the Northern Line, which is 7 minutes longer.

Travelling to London Bridge? 19 minutes by Northern Line, or 30 minutes by Crossrail changing at Angel to the Northern Line (Crossrail 2 has no access to the Jubilee Line). That is 11 minutes longer by Crossrail.

And Canary Wharf? It is around 30 minutes on the Northern and Jubilee Lines, and around 31 minutes on Crossrail (Crossrail to Canary Wharf is a low frequency service at 12tph).

For completeness, Crossrail 2 will of course save large amounts of time for journeys to the West End near Victoria, Leicester Square and Euston.

Putting the pieces together

Given these two key points - relative capacity and journey times - the real question is whether routing Crossrail 2 via Balham (or Tooting) makes sense. People generally take the quickest route.

To summarize, these are what I calculate to be the quickest routes:

• Any station from Morden to Tooting going to London Bridge, Bank or Moorgate - stay on Northern Line
• Any station from Morden to Tooting going to Canary Wharf - Northern Line then Jubilee Line
• Any station on Crossrail 2 via Wimbledon going to London Bridge or Bank - change from Crossrail 2 to Northern Line
• Any station on Crossrail 2 via Wimbledon going to Moorgate or Canary Wharf - stay on Crossrail 2 and change to Crossrail 1

Thus there are two conclusions:

1) No one already on a Northern Line train approaching Balham and heading to London Bridge, the City or Canary Wharf will change onto Crossrail 2.

2) Anyone on a Crossrail 2 train from Wimbledon and heading to London Bridge, or the south part of the City will change onto the Northern Line.

Given these conclusions, TfL's claims that Crossrail 2 will relieve the Northern Line look very very duboius. Just think about the sheer number of jobs in the City and Canary Wharf if you have any doubts.

And as a final kicker, routing Crossrail 2 via Balham (or Tooting) is considerably more expensive than routing it via Earlsfield. A topic that will be the subject of my next article!

Summary

Each Northern Line train is a lot smaller than each Crossrail train, so relief of the Northern Line depends on few people transferring from Crossrail 2 to the Northern Line. Unfortunately, journeys to key destinations such as London Bridge and the south part of the City are quicker by changing from Crossrail 2 to the Northern Line.

As such, this analysis suggests that routing Crossrail 2 via Balham or Tooting is highly unlikely to reduce crowding on the Northern Line by much and may well make it worse.