Have you been on a train recently?  Standing all the way from Manchester Piccadilly to Euston is no fun 😞

The whole network is severely short of capacity - we need new lines not only between London, the Midlands and the North but from East to West as well.  If new lines are going to be built then they might just as well be built to the latest specifications.

The idea of building lines above motorways sounds good in principle but the reality is that such plans would disrupt traffic for years and cost the country a fortune - much better to build alongside them where possible and go underground, (like Crossrail), near city centres.