Wo toh depend karta hai train type and round trip distance pe..Agar round trip run upto 3500 km for ICF and upto 4000 km for LHB hai toh Secondary Maintenance mein Internal cleaning, passenger amenity attention and watering hota hai, jiske liye Pit line pe le jane ka jarurat nahi hota..Jaisa 12487/8 ke sath JBN mein hota hai.
But agar round trip 3500 km for ICF and 4000 km for LHB se jyada hai toh fir Pit line le jane ka jarurat hota hai..JBN mein pit line hai nahi toh yeh train 19483/4 ka JBN extension feasible hi nahi hai.