I responded to an invitation elsewhere to comment on possible Open Street Map (OSM) handling of this issue. Here seems like a less obscure place for my further remarks on OSM and the general issue, now that I have looked at local changes as an example
1. The underlying situation is probably fairly scandalous. A charity has had public funding to mark NCN routes for decades, either from the state or private contributions, but has decided that it no longer likes the idea, so is actually intending to go round removing the markings. It is particularly scandalous for the former county cycleways which were local authority projects, which existed before Sustrans and had their own marking. If Sustrans want to fiddle with the current markings they should required to revert to the original numbering, for example 10 for the Avon Cycleway.
2. For OSM mapping it is going to be difficult to define an OSM policy relating to on the ground signing of routes that are under someone else's control, or no ones control, and where the current controller has said that they will remove the signs over the next two years. If the routes are useful the solution is above OSM level in the political sphere: someone else, presumably local authorities has to take responsibility. OSM could then continue to map what exists.
3. There may be another solution, if you consider that if the routes had been created today, in the era of GPS they might not necessarily have been signed. This suggests that the solution suggested in the OSM wiki, of marking them as 'NCN abandoned', or similar, perhaps 'NCN assasinated' could be used in cases where OSM considers that they are worth marking. The latter decision is effectively what OSM does for roads and tracks when grading them for traffic levels of bicycle use.
4. Examples:
4.1 My comments are based on the Avon Cycleway, which seems to be one of the routes degraded on the new map:
https://osmaps.ordnancesurvey.co.uk/51. ... 2.75577,13.
It existed and was signed before Sustrans, with brown 10 signs, and the signing, now blue 410 sometimes with a brown 10 inset, will presumably continue to exist for some while, unless budget and volunteer effort is really to be diverted to an energetic sign removal programme. The signs are useful, particularly on the link routes, when picking your way round the edge of parts of the town that you do not know well, or just to avoid stopping to read the map at every junction.
The cycleway has always had the problem of some busy sections, which were marked on the original maps, for example the B3130 Barrow Road road to Winford is in the Clifton Link, still signed and still used by cyclists as the direct continuation of Hobbs Lane. One of my 1:50k OS maps shows this replaced by a short stretch of the A38 to reach the Felton Road, presumably in the pious hope that the pavement would be designated as shared. I have long ago given up using the B3130 in favour of walking the 600 m up the A38. So you could argue that, like the Sustrans network, the county cycleways never existed in complete form, except as a route suggestion for experienced cyclists, or in quadrants, using the links for less experienced cyclists who read the warnings on the map.
It might be that had the county cycleways been created today, in the age of online planners and GPS, no one would have expected signs on the ground, or possibly would have concentrated on signs warning of the presence of cyclists in the busier sections. Perhaps that is the real utility of the blue route signs.
4.2 The Sustrans changes are rather odd. The quiet narrow back road down the Gordano Valley has been reduced to 'not on the National Cycle Network', whereas the drag strips of Manmoor Lane and Kenn Road, which have some very fast traffic, remain as 'On road route on the National Cycle Network', presumably because they line up with the Strawberry Line. Anyone using the new classification as a guide to traffic conditions could be very surprised. It may be that the Gordano back road has been removed because Sustrans are promoting a scheme to create a mostly off road route on the line of the former light railway on the other side of the valley, and having an NCN marked on the opposite side, about one kilometre away, might hinder the business case.
Keeping NCN41 north through Oldbury is perfectly sensible, reducing NCN410 from Thornbury over to Horton and then back round north of Yate seems odd as the roads are much the same quality, and it actually provides a useful guide to some of the more obscure bits in the urban fringe. Presumably because the principle applied has been to tell the work experience lad to downgrade NCN410 apart from the off-road bits.
The route North through Henbury to Cribbs Causeway is shown as a traffic free part of the network, which it is, if your definition of traffic free is teetering along a narrow shared pavement. Then there are the odd doglegs. Who thinks it is necessary to dogleg NCN4 along Reedley Road, Stoke Lane and Stoke Grove rather than heading directly to Coombe Lane? Strictly, I think this is also a local link route, not NCN4, but the OS map does not make the distinction.
5. I think this points to the conclusion that the NCN is a mess that has never formed a coherent network, and Sustrans moving to define its job as traffic free routes only may be sensible from their business viewpoint, even if this leads to an NCN comprising a series of fragments. This may be the object; if the gaps in the NCN become obvious it may be easier to ask for funding to fill them with off road routes. From the public viewpoint this does leave us with some perfectly useable routes, which still have signing, and are worth maintaining as ideas for outings or utility use. I suggest that where signing exists the route should continue to be marked, both on the ground and on OSM with the number on the signs, at least for sections that are considered useable. Possibly we need a general OSM tag for 'Duff bit of official cycle route' for the parts that are not, rather than leaving users to work this out from the details.
6. We do seem to be heading towards a National Cycle Network comprising the parts of the current network that I now avoid or hurry through, because they are bumpy or busy, or convoluted.
Orignal Avon Cycleway sign still in place deep in the Avon countryside:
