NR NR/SIN/128 ISSUE 1 PDF

The scope of the Special Inspection Notice applies to MCB-OD level crossings that are controlled by relay based circuits. Those crossings that are known to be in scope and are already commissioned are listed in Appendix A.

Those MCB-OD crossings not listed are controlled directly by electronic control systems that will not be liable to the issue and therefore do not need modifying.

Purpose

The purpose of this Special Inspection Notice is to define remedial actions to be taken following discovery of a wrong side failure mode at certain manually controlled barrier level crossings with obstacle detection (MCB-OD). The action, when implemented as prescribed, is designed to mitigate for the failure of a relay due to high contact resistance leading to wrong side failure. The nature of this failure may lead to an irregular barrier raise due to a delayed call, as well as intermittent failure of the barriers to operate as required.