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!
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.