There is a recent update about RRB 2016 written exam. Though, RRB has not released any formal notification, however, a lot of RRB 2016 applicants have received sms from RRB stating:
"Due to unavoidable circumstances, your NTPC (graduate) examination has been rescheduled to a later date. Your revised date and venue will be communicated to you shortly. - Railway Recruitment Boards"
For now, the final update is exam is rescheduled. We will keep you posted on the next information or a notification from RRB.