Congestion worsened despite road improvements

[Haltamer]

https://www.bbc.co.uk/news/uk-england-47845050

There's a suprise!
I haven't done specific research on each of the projects, but by the looks of things they were the usual bandaid "smart motorway-esque" improvements that attempt to eke incrementally more capacity from the same road / junction layouts, without considering the overall design.