This train is actually 2 trains merged as 1 train. Some coaches come from Dhanbad and some from Tatanagar. Both the parts are merged at Rourkela and thereon run as single train to Allapuzha. In return from Allapuzha, both parts run combined till Rourkela from there both the portions (Dhanbad and tata) are separated before they proceed to their destination.
Two trains are
1. 13351/52 Dhanbad Allapuzha express
2....
more... 18189/90 Tatanagar Allapuzha express.
Here Tata allapuzha is slip/link service and its coaches are numbered as ST 1, ST 2....