NR NB 107 ISSUE 2 PDF

This Notice Board is intended for persons carrying out Signalling Failure Investigations in accordance with the current Signalling Maintenance Testing Handbook (NR/L3/SIG/11231 Issue 4) Part 5. It applies to persons holding Levels 1, 2 and 3 of the escalation and sign-back authority defined in NR/SMTH/Part 5/S001, but in particular to staff responsible for final approval (L2 or L3) who should make sure that they consider possible causes broadly and challenge teams seeking to sign-back into use equipment that has been alleged to have failed wrong-side, so that the risk of missing a wrong-side failure mode is minimised.

Purpose

This Notice Board explains the circumstances in which a possible scenario which could have led to a SPAD occurring was missed during Signalling Failure Investigation. It is issued as a "lessons learned" exercise to remind persons carrying out such investigations to think broadly about possible causes of a reported failure.