In reply to TheGeneralist:
That's a good question, I'll ask them.
If you design-in for MTB then do you also have to account for an increase in erosion, and a different sort of erosion than you'd get from footfall? Would a multi-use hill path be built differently?
I'm thinking of loose chip surfaces being worn down, or those tyre scores you see on soft ground that seem to act as water channels for runoff (more damage per bike than a set of footprints?).
Are hill paths more a walker concern because they are the primary infrastructure for walking in the hills? Whereas MTB-ers already have lots of trail centres, and thousands of miles of gravel estate tracks that are better by bike than on foot. For bikers, is going up hills a minority activity and thus less of a consideration in the scheme of things?
Not sure what I think about any of this. Guess my principle would be the hills are for everyone non-motorised, so long as they're not doing more than their fair share of damage. But I really don't know to what extent we ought to account for two wheels when maintaining hill paths: there's got to be a conversation in there.