Question
I have a 30 ft Colorado blue spruce in my front yard. Its root system has cracked the front walk, which is 4 ft from the edge of the walk. I want to replace the front walkway but am concerned  that all 3 estimates I have received warned me they would cut any roots they encountered.
I don't want to weaken the tree and understand from 2 arborists i consulted that the root system is shallow (6 - 12 inches deep). The concrete replacement requires a 5 inch subsoil depth.
The arborists suggested root pruning w/ airspade before walk replacement. Won't that weaken the tree as well?
Could you suggest a softer walkscape that might not involve 5 inch depth prep?

Answer
The root system is with in the first 2 feet of soil. You can get by with cutting up to 25 % of the roots But even this can cause some dieback of foliage on the side toward the root cutting. Instead of a solid cement walkway you might consider pavers in a sand bed. The sand is put over the roots (try not to add more than 3 inches of sand over the exposed roots) the pavers are put in the sand. This may raise the height of the walkway a little. IF a root or two is cut it will not effect the tree as a if you cut all the roots on one side of the tree. Paver come in all sizes for 6 inch squares to a couple of feet and several colors.  Here is web link to pavers used for walkways.

http://www.paversearch.com/walkway-pavers-menu.htm