JammyDodge wrote: ↑Mon Nov 01, 2021 20:52
jackal wrote: ↑Mon Nov 01, 2021 14:44
we can all at last retire our Lofthouse crayons
I got the crayons out
J42-43 theoretical braiding solution
M1 J42-43 Braid.jpg
Just when I thought I was out, they pull me back in.
Your sketch has the right idea but it has mainline weaving north of M1 J43 on both M1 and M621, and it also severs access from the M1 to M621 J7. This plan resolves these issues:
The basic concept is the same as yours, i.e., (1) remove the M1 TOTSO and (2) resolve route choice at Lofthouse (J42) north of J43. So the section between J42 and J43 consists of the M1 mainline (inner carriageways) and extended slips from Lofthouse (outercarriageways). But there are also C/D lanes (M1) and braiding (M621) north of J43 to handle weaving there while maintaining full access.
It might actually be possible to fit all of the C/D lanes under existing bridges, which have a decent amount of space, though the speed limit may have to be dropped in places as sightlines would suffer. The M1 J43 to J44 C/D lanes would just be 2+2, so fit under the Wakefield road bridge, which is D3M plus verge. J42 to J43 definitely fits for 3+2, accommodating two lanes for the turning movements at Lofthouse as at present. (3+3, allowing three lanes for the turning movements, might require the Sharp Lane bridge to be replaced, though I'm not convinced the extra lane is actually needed if weaving issues are resolved.)
J43 itself would need one new bridge (the existing bridge is the other bridge needed there) and two more are required for the braiding north of there. So though this looks very complex it may require only three new bridges, and the only significant landtake is for J43 and the braiding north of there.