Section 24(4) in The Delhi Metro Airport Express Line, General Rules, 2010
(4)No train shall be driven on a running line from the rear cab except,-(a)a locomotive working within an Engineer's Possession under the control of hand signals;(b)in exceptional circumstances, when authorised by an official not below the grade of Operations Control Centre Traffic Controller and a look out shall be positioned in such cases at the leading end with the capacity to apply the emergency brake and the speed of the train shall not exceed ten kilometer per hour in such cases.
