What does 'vehicle access' mean ?

[ANiceSliceOfCake]

This isn't an issue just yet but I'm just thinking ahead. We have vehicle access to get to our back garden over the garage area of the neighbours land.

It's a piece of land to the rear of the block of houses where we live that we cross over.

But my question is, if the owner was to build on it how much room do they need to leave for my vehicle access?

is there not a minimum width defined on the deeds/covenants . We have to leave 4' for our neighbours path.

I'll have to have another look, I couldn't see a specific width.

Or it may on the landowner's deeds.