Section 7(2)(c) in The Railway (Notices of and Inquiries Into Accidents) Rules, 1998
(c)collusion, between a Road Vehicle and a passenger train at a Level Crossing where no passenger or Railway Servant is killed or grievously hurt shall not be treated as a "Serious Railway Accident" even if those travelling in the road vehicle are killed or grievously hurt shall not be treated as serious railway accident, unless the Chief Commissioner of Railway Safety or Commissioner of Railway Safety is of the opinion that the accident requires the holding of an inquiry by the Commissioner of Railway Safety.