Good topic, Kevin. I also have had problems accessing cal courses when one or both endpoints have disappeared due to repaving. One recent cal course I needed to use had clear endpoint descriptions that allowed me to carefully measure to these points and drive in new nails. Another paved-over cal course I recently needed to use was impossible to recreate because the description of one endpoint was based on fixed objects that weren't - fixed - it seems, because they were nowhere to be found.
I haven't attempted to set up a cal course on my own, though I know there are practical methods (described in this forum) to do so. I believe that the probability of establishing a fairly exact cal course improves with 2 people on the job. However, I would be happy to be convinced otherwise.