Traffic into Madras today is already a huge issue, supposedly. Now, in addition to the normal ecliptomaniacs, there are 35K people who are expected to attend the "Symbiosis" festival as well, and all the roads in and out of that area are two lane.

http://www.sfgate.com/news/article/e...s-11942253.php

This is an interesting article about the "drivesheds" of traffic that may converge on different places. A few random ones that you would not expect could, in theory, be significantly impacted if people primarily drive to the eclipse at the location closest to their homes.

http://www.businessinsider.com/solar...y-maps-2017-8/