How to cut an arched top wood fence

A tree recently fell on our arched cedar fence. I purchased new planks that were a few feet too long in order to have enough extra wood to cut the matching arch. To recreate the exact same radius, I used a piece of 1" PVC pipe bent from corner to corner of a single panel. A perfect arch can be traced on the new boards. Then cut with a standard circular saw.

This technique makes a traceable template for each panel section: