In madurai after electrification,WAP 4 started ruling madras bound trains WDP 4 which hauled are given rest for vaigai exp and pandiyan exp........And in madurai there is a rescue loco WDP 4 when enquired to a loco pilot he said this loco will be idle and if any problem in midway towards chennai this will be used for hauling those trains ...This new technique is followed by madurai divison and he also said in upcoming days after the complete electrification of MS-CAPE Section ther will AC locos WAG 9,WAM 4 which will be acting as recue loco in madurai divison