Wow great explanation and I learnt something new today . So for Kerala SF it undergeoes PM at TVC and SM at NDLS isnt it? also I have a question , you said blackdiamond goes for BPC after every 4 days, when it goes after 4 days, how many hours does it take to undergo BPC, if its 8 hours the train doesnot have that much time at Dhanbad isnt it to undergo PM ?