Very noisy train, looks like the coupling of the coaches is loose. I travel every week from Bangalore to Chennai and sleep is always disturbed by the noise. It is like a newly learning car driver driving a car and causing jerks while shifting gears. But it is iron...metal...clinking noise...while you are in sound sleep. Never noticed this kind of nuisance in other trains. Wish railway authorities make note of this and take appropriate corrective action.