It's not just the section of the A46 around Lincoln which is dire! When the Leicester - Newark section was finally dualled in 2011, that left a ridiculous single carriageway section around Newark which is a real bottleneck, plus a really dangerous roundabout junction. It seems that this may well be dualled too, but work won't start until 2020-ish...
Lincoln's western bypass is a travesty - particularly where dual carriageway sections become single carriageway. The roundabout junctions can't really cope with large vehicles either. It should have been built as a dual carriageway for the entire length to the A15 junction.
They're now building an eastern bypass from the A15 to Wragby Road - but again that's all single carriageway, so will undoubtedly become yet another bottleneck.
The 'missing link' between the A46 and A15 might become the 'North Hykeham relief road', but again there's doubt about whether it'll be a dual carriageway.
I've been driving from the south west to Lincolnshire since the late '60s. Parts have improved as anyone who ever remembers the magical mystery tour of the Leicester ring road and the subsequent crawl up the Fosse Way will probably agree. But until there's a proper dual carriageway along the entire length from Leicester to the A158 Wragby Road, it'll always be inadequate.
As for the A15 north to Hull - well, it's a lot better using the A15 and a bit of M180 to the Humber bridge than the old crawl through Brigg to the New Holland ferry and the 40 year old paddle steamer to Hull ever was!