well glass city,a very good morning to you. It has been calculated by railways that 3a has been the most profitable class for them. How they did this is unknown to me. And it is just due to this reason,that more emphasis is being paid on increasing class 3a in each and every train. In many of the trains in eastern railways, sleepers and pantry have been removed and class 3a have been added...eg.hwh jodhpur express, saraighat express,darjeeling mail,etc...