I rode a short section of part of the western half of the Ridgeway many years ago, and my hazy recollection is that parts of that particular section were extremely deeply rutted by 4 x 4 use. What made the ruts particularly bad was not just the depth, e.g. 6", but the fact that the sides of the ruts were often nearly vertical, so if a rider was not very careful and their front wheel strayed into a rut, the front of the bike would drop into it very suddenly with a hard jolt.
I think that there are only limited discrete sections of the Ridgeway that are Byways Open to All Traffic*, and I remember reading since I rode on it that there have been restrictions on motor vehicles using them during the winter to reduce the damage they cause when the track is muddy.
Does the section of the Ridgeway forming part of King Alfred's Way include Byways Open to All Traffic*, and has any assessment of the condition of those sections been made to ensure their suitability?an
Even if the winter motor vehicle restrictions have reduced the damage and ruts, it might still be necessary to estimate/measure the number and the impact of 4 x 4s etc. which would be encountered by cyclists on those sections, especially narrow sections where there would not be enough space for an oncoming or overtaking 4 x 4 to go safely past the cyclist without the rider pulling off the track.
* Edit - I see that they are not Byways Open to All Traffic, but Restricted Byways:https://www.nationaltrail.co.uk/ridgeway/news/driving-ridgeway-and-what-do-if-you-see-illegal-activity
Answering one of my own questions I can see that the section of the Ridgeway forming part of King Alfred's Way does include Restricted Byways:https://www.nationaltrail.co.uk/ridgeway/information