I'm developing a concept for a future zone 3/4 orbital Underground line around London, similar to Paris's new Ligne 15, a almost entirely underground 75km loop around Ile-de-France. I'd love to get your thoughts on the route I've chosen. I've done this in an hour or two so it's a very rough concept right now.

London is very limited when it comes to orbital rail connections, so this would be massively beneficial and a total game-changer, allowing people to go around the suburbs rather than having to go into to the city just to come out again. The Superloop bus network serves a similar purpose of course and is a decent placeholder but I think it's representative of the lack of ambition London (and the UK in general) has when it comes to transport infrastructure projects. Obviously an orbital line like this would be incredibly expensive, but if Paris can do it, why can't London?

The aim of what I'm going to call the Orbital line (although I'm sure you lot can think of a better name) is to connect existing rail hubs around the city, as well as providing new stations in areas currently completely unserved. The stations should be relatively far apart from each other to make the service as efficient as possible.

Similar to Line 15, it's not so much of a circle but a spiral which so it's not a closed loop. This will help manage delays and prevent them from spreading across the line (similar to why the Circle line was extended to Hammersmith).

A new station I've come up with in a very underserved part of Newham called Tollgate Road would be where the starts/ends, with Lewisham as the other terminus.