It had been assumed that TfL's route for Crossrail 2 between Wimbledon and Victoria was set in stone, but there has been recent talk that the Tooting Broadway station is under debate as a result of difficult ground conditions. This post provides a set of possible routings for the section, beyond the Balham option TfL is apparently looking at.
Balham instead of Tooting?
This blog has long argued that Crossrail 2 should not go via Tooting, but the suggestion of Balham comes as a surprise. In some ways it is less of a dog-leg, but in others it is more of one. Clearly, the desire to route via the Northern Line is very strong.
To aid the debate, I've drawn a map showing a set of what might be considered viable options and stations. Of course there are many more options in reality, but too many can make things less clear (thus, no options are shown via Wandsworth for example).
The TfL routes are shown in red (light red for Tooting, dark red for Balham). Other potential routes in purple.
Here is my measurement of the distances involved:
|Route (between Wimbledon and Victoria)||Distance||Excess over shortest route|
|Tooting, Clapham Junction, Chelsea||11.9km||27%|
|Tooting, Clapham Junction, Battersea Power||11.4km||21%|
|Tooting, Clapham Junction, (direct to Victoria)||10.9km||16%|
|Balham, Clapham Junction, Chelsea (my estimated route)||12km||28%|
|Balham, Clapham Junction, Chelsea (TfL actual proposal)||12.9km||37%|
|Balham, Cedars Road, Battersea Power||10.5km||12%|
|Earlsfield, Clapham Junction, Chelsea||10.3km (4km surface)||10%|
|Earlsfield, Clapham Junction, (direct to Victoria)||9.4km (4km surface)||0%|
From this I draw some conclusions:
1) The shortest route is via Earlsfield and direct to Victoria. Routing via Chelsea or Battersea Power is quite a diversion between Clapham Junction and Victoria. This also involves the least tunnelling (as the portal can be north-east of Earlsfield).
2) Tooting Broadway is a long way south and east between Wimbledon and Clapham Junction. Hence the "dog-leg" moniker for the TfL route. The total excess distance of 27% is high. (The TfL routing map was published later with a higher excess).
3) Balham is further east than Clapham Junction. As such, a Wimbledon - Balham - Clapham Junction routing is more indirect than via Tooting Broadway at a total excess distance of 28%. (The TfL routing map was published later with a higher excess of 37%).
4) Balham to Victoria via Cedars Road and Battersea Power is a simple straight routing, with an excess distance of just 12%. If chosen, it would probably push the Northern Line Battersea extension to reach Clapham Junction sooner rather than later. It does raise the question of whether Crossrail 2 really needs to serve Clapham Junction? ie. could interchange with South West Main Line fast services happen at Wimbledon instead of Clapham Junction? Note that the station at Battersea Power would need to link to Queenstown Road station to be effective.
Finally, I'll note that the Balham option provides for a station in the Wandle Valley. This has the potential to deliver a major housing development. Given the pressing need for housing in London, and the funds housing brings, this could be a major factor in any decision.
Happy to hear your thoughts in the comments!
Update 2015-10-28: The real map from TfL has arrived, and demonstrates how routing via either Balham or Tooting involves an even more stupid routing than my map above! Calculated as a 37% excess over the shortest practical route.