I have a weeping Caragana pea tree which is 25 years old & im concerned about how thick the trunk is becoming also wondering about
what length the root system might be I'm wondering if I should start with a new tre as I'm having part of my front garden altered to drive for my car &I not sure if in time the roots from the existing tree could pose a problem to the new drive which is going to be mono block
It's a shame to lose a mature tree for the sake of a driveway, but yes, tree roots and pavers are not a good match. Beside root length, they expand in girth and can lift and displace the pavers.
If you value the tree, consider alternative routing of the driveway, or root pruning and installation of a root barrier.