Section 37(3)(a) in The Bangalore Metro Railway (General) Rules, 2011
(a)Sensors are provided to detect any person trapped between train door and Platform Screen door at station with curved platform, when all platform screen doors and platform edge doors are closed by the train operator, the sensors shall check and give following indications on Platform Screen door local panel at both headwall and tailwall:(i)nobody trapped - Green; and(ii)somebody trapped - Red flashing,