I have an earlier (pre-digitised) copy of the John Evans map that I had attached on the post above, and it seems obvious to me that the digitised map from the national library is not quite the same as the original copy that I have attached below.
The Evans maps are a series of county maps of Wales that were drawn between 1793 and 1795 and I had previously taken a screenshot of the original map from an online source, which I had to magnify significantly. While the digitised copy of this map on the National Library website is far clearer than my original copy, there are obvious discrepancies between the two and it would seem that the digitised copy has added in little details that were not present on the original map. It is as if the digitising process has added detail to match the rest of the map and therefore added a small section of road, whereas, on the original copy, the road was just a boundary line and a square section where the Turf is now located. I have no idea how the two copies of the map could be different, unless the digitising process has added in new detail.
There is also another map in the National library, dated 1834
https://viewer.library.wales/4997612...41%2C698%2C518
and this map has a boundary line highlighted in the exact area where the road is, and so it seems as if some of the details from this map have been introduced onto the digital version of the earlier map, thereby resulting in the road being drawn into the 1793 map.
None of the other maps, either earlier or later, show a road in this area, although some show a boundary line where the road is drawn, and therefore I think that the road on the map has just been added by some kind of digital software during the digitising process, but in reality, the road wasn’t really there.