KiwiRail’s change management process for upgrading the signal box display had not ensured that the mimic screen matched the physical track layout, and had not detected the absence of an interlock to prevent the signallers setting the points to a configuration over which it was not possible for rail traffic to travel.
On 23 May 2018 the Commission recommended that the Chief Executive of KiwiRail review KiwiRail’s change management processes for modifying existing and building new safety-critical systems, and ensure that these change management processes include a full failure mode effect analysis and require functional testing before the new or modified systems are put into service.
