scope:

This SIN applies to signals fitted with Dorman LED signal heads (all varieties) that perform the function of a mid-platform or platform starting signal, i.e. on a platform or less than 200m beyond a platform;

NOTE: The highest risk is where drivers regularly stop in the same position which coincides with the position a phantom aspect can be witnessed. Stopping positions at non-platform starting signals is less regular therefore the likelihood is lower.

It does not apply to:

a) signals fitted with TPWS TSS;

b) signals fitted with CD or RA indicators;

c) signals that do not perform the function of a mid-platform or platform starting signal.

NOTE: This is because the consequence is lower or the risk of occurrence is mitigated, and all other Dorman LED signals will be subject to a routine maintenance task including a check that it is aligned in accordance with NB 179 within 4 years.

Purpose

The purpose of this Special Inspection Notice (SIN) is to check that all Unipart Dorman signals that have a high safety and performance risk of displaying a phantom aspect from reflected light (from any source of sufficient luminosity) are aligned in accordance with guidance provided in NB 179. A HAZID was undertaken to identify the highest risk signals and the results are shown in Appendix C.

NB179 supersedes guidance within NR/L2/SIG/10158 Appendices C.11.2 and C.12.2, SIN120 and TI151.