Sir it is not necessary that always rajdhani like trains will get robbed. Its railways responsibility that RPF should be present in trains specially in overnight trains. I've heard similar incidents in other trains that runs in old ICF coaches. Similar incident also happened in kerala sampark kranti twice near BRC. Throwing stones to the trains is common in faridabad area. Once I was travelling in TVC rajdhani some kids were threw stones to my train in somewhere between TKD & FDB & it broke the windows. Sadly only solution to this problem is fencing but I don't think that would happen in near future.