Because PF 8/9 are used for the below tagged
Trains
1) Gaya - Jasidih Shravani Mela Special/03652
2) Raxaul - Hyderabad Special Fare Special/07006
3) Barauni - Secunderabad Special Fare...
more... Special/07010
4) Patna - Kolkata Express/13132
5) Darbhanga - Secunderabad Special Fare Special/07008
6) Gaya - Patna Special/03298