"Roland Perry" wrote
John Salmon remarked:

There are some examples of poor signage where roads merge and then
separate. The A57 - the main route from Lincoln to Sheffield - merges with
the A1 between Markham Moor and Apleyhead, but drivers approaching Markham
Moor from the Lincoln direction are given no clue whatsoever as to the
correct route to take, and it is not at all obvious. The A57 just
disappears.

I don't think the brackets indicate a merged route. They simply say that
"if you take this route you'll eventually get to the bracketed road".

I didn't mention brackets - that was the previous poster.

This is consistent with your observation at Markham Moor... the A1 is not
intended to be a road "merged with" the A57, the latter road simply stops
there.

But it starts again a few miles along the A1. What is that if it isn't a
"merged route"? [1]

Go north a junction, and there are signs pointing north saying "this way
to Doncaster on the A1, and incidentally this leads to...

Not "leads to"; it *is* the A57...

... the A57 for Sheffield and W******"; [2]

I still think the situation at Markham Moor, as viewed by a driver going
from Lincoln (on the A57) to Sheffield (on the A57), is most unsatisfactory.

[1] Incidentally, the A57 has been merged with the A1 between Markham Moor
and Apleyhead (formerly known as Five Lane(s) End(s)), (and the A614 has
been merged with the A1 between Apleyhead and Blyth) ever since the combined
Retford/Doncaster bypass opened around 50 years ago. Prior to that, the
stretch of road being discussed *was* the A57.

[2] Expletive (from the point of view of a Retfordian) deleted.
:-)