Ananthapuri Express is an express train running between Thiruvananthapuram Central and Chennai Egmore via Tiruchirappalli and Madurai through the chord line. It is a daily overnight service. From Chennai Egmore, train no:16723 departs by 19:35 hours and reaches Trivandrum Central at 12:10 hours the next day. The parallel train numbered 16724 starts 16:20 Hours from Trivandrum and reaches Chennai around 08:40 hours the next day.
Anantapuri Express Wikipedia
It runs along the chord line through the shortest route to Chennai via Nagercoil, Tirunelveli, Madurai, Virudhunagar, Trichy, Villupuram and Chengalpattu.