since the 1960s, British motorways have been deliberately designed as series of long curves, rather than straight lines. This is done for both safety (less hypnotic) and aesthetic (“sculpture on an exciting, grand scale”) reasons.

you can read a lot about it at https://books.google.co.uk/books?id=bGIgduj1cUEC&lpg=PA34&ots=2mXaGhWr99&dq=m4%20road%20curves%20computer&pg=PA34#v=onepage&q&f=false  via https://medium.com/fluxx-studio-notes/52-things-i-learned-in-2019-8ee483e6c816