Never Travel using 2S (Second Sitting) in Guv Chennai Exp especially in long distance. The seats are horrible and you will be pretty tired. I booked the 2S from Thrissur to Tirunelveli because sleeper or AC – 2/3 tier was unavailable. I boarded from Thrissur around 9:20PM – soon the compartment was filled up with loads of people and I found it very difficult to even sit properly. The toilets are also horrible. It was only when the train reached Nagercoil Jn, it became less crowded and I was able to lie down and sleep for about 2 hours till I reached Tirunelveli.