Yesterday the mayor’s office released its £1.3trn (yes, trillion) London Infrastructure 2050 plan. The document contains all sorts of goodies for the sort of people who get all excited by the prospect of new transport infrastructure (i.e. us), so we’ll no doubt be writing about it rather a lot.

Perhaps the most striking proposal it contains, however, is the one for a new orbital rail link, which would connect a string of existing lines to the Overground Network and which, according to the Guardian, is referred to by officials as the ‘R25’, after London’s orbital motorway.

Sadly, though, the map in the report is a bit on the vague side…

…so thought we’d flesh it out a little.

We can’t promise that what follows is an entirely accurate reflection of City Hall’s plans: In a few places we’ve had to guess where the new line would go, based on the jagged twists and turns on its own map.

We’ve assumed, though, that TfL would prefer to use existing lines wherever possible, and so would only construct new track where it had no other choice. (We’ve marked these bits using hollow tramlines.) We’ve also resisted the impulse to add new stations willy-nilly, and only included them where it seems almost certain the powers that be would do the same. (These are marked with ticks rather than interchange roundels.) Even so the project is just a teensy bit on the ambitious aide. 

 

As you can see, the new network swallows up the Gospel Oak to Barking line and the Bromley branchline; takes in large chunks of the North London Line, the Wimbledon-Sutton loop (currently part of Thameslink), the Kingston loop (currently South West Trains); and uses chunks of assorted other lines. It also means bringing the long forgotten Neasden spur back into passenger service.


Most ambitiously of all it implies several new tunnels – in Wimbledon, Bromley and, biggest by far, under the Thames from Barking down to Sidcup. You could run this latter section above ground – but only if you were willing to bulldoze large swathes of Kentish suburbia.

The whole thing looks distinctly like London’s answer to the Grand Paris Express plan, which will see four new orbital lines built over the next two decades or so. But the Infrastructure Plan stresses that this project is “not included in the costings”: even if the engineering challenge could he met, how much all this would cost remains to be seen.

So, it may well never happen. But you can forgive the authorities for dreaming big once in a while.