Right of Carriage way

Depends if it impedes access to your land.

Impediment in this case can include not just physical obstruction
(like, say, a fallen tree not dealt with, or a pile of gravel blocking access).

Rather, impediment can also include the path itself being in (being allowed to fall into)
such poor condition that it could damage or obstruct vehicles using it.
Not only your private vehicle(s), but also, say, ambulances, fire trucks, and even delivery vans.

In either scenario, you could probably get an Order requiring him to (at least help) fix it up.

That being said, without his consent, you have no right (nor he a duty)
to do anything that looks like a capital work.
By that, I mean that while you appear to have his consent to maintain it,
you do not have a right (and he has no duty) to upgrade it.
For example, I do not see that you have a right (nor he a duty)
to upgrade a graded dirt track to a compressed roadbase path,
let alone to a sealed surface.

In general, the servient title holder has no obligation to contribute to road repair

however, this is subject to the easmentt wording

you do have implied rights, ie you can’t have your safety being compromised when you use an easement,