> I understand the electrical system was shot.
To the layman/railfan that means doom. However it could be several minor factors such as MG flashovers, TM flashovers, faulty obsolete relays and contactors, or just perished insulation on the HT cabling and/or LV control wiring.
That is very easily solved with Managemental commitment, and a $$,$$$.00 outlay. Maybe the D&Sng should call Kiwirail and discuss the Brightstar programs.
Call it an insurance plan if you like, like upgrading the track before a serious derailment occurs, all which may become apparent in due course.