I lived in London from 2004-15.<p>There&#x27;s been massive demand beyond available capacity for over a decade, but perhaps not much over a decade. That&#x27;s about how long it takes to plan new lines.<p>I used the West London Line before it was the London Overground. Within a month or two, it went from a little-used train to not getting a seat. Areas like Dalston went from being places I was warned to avoid (as a student) to having loads of new nightclubs. The closure of the East London Like wasn&#x27;t a massive issue beyond the local area, few people used it.<p>I expect the same to happen with Crossrail, and Crossrail 2. Royal Oak will become known, etc.<p>London needs two or three of these project to be built simultaneously, to catch up to what is needed, but that can&#x27;t happen - there aren&#x27;t enough skilled engineers in the UK. (This is why the plan to electrify all the remaining national rail lines stalled.)<p>Where is there a multi level rail line? I&#x27;ve never seen one, except within a station.