Here is a URL where you can download a zip file with the ATC 2009 centerline-track data with USGS digital elevation data for each track point.
You can do your own elevation studies. On the page below, the data is used to determine the top 5 steepest half-mile and mile sections as well as create graphs of elevation profiles between shelters.
http://web.eecs.utk.edu/~dunigan/at/atelev.html