Richard Fairhurst wrote:reohn2 - Ah, I see. Faulty/missing surface information in OpenStreetMap, which cycle.travel uses as its source data: Crankwood Road was marked as a paved road, while the towpath wasn't marked as paved/gravel. (Generally cycle.travel takes a cautious view, so if a towpath doesn't have surface information it'll steer clear.)
Essentially all online routers use either OpenStreetMap or Google as their routing database. OSM generally has more information relevant to cyclists, but as a volunteer contribution project it's only as good as the local contributors! I've tweaked the surface information from what I could see on the aerial imagery, but hopefully a local will be able to refine it further.
I've added the "gravel" surface tag to a couple of bits of the towpath towards Wigan that were unmarked in OSM so that should help encouraging routing along the canal.
I've also graded a couple of section that are marked route 55 south of Hindley & Hindley Green as "mud" as that is an appropriate tag. They were dry when I tried them in the middle of the summer's heatwave but I could tell that wasn't their normal surface consitency.
I'd seen Crankwood Road on the map & wondered what it was like - Streetview has covered the tarmac bits but no indication of what the intervening bits are like, The Ordnance Survey mapping just has a white road which could mean anything.