scope:

This SIN applies to:

o Full-depth facing switches in Track Categories 1A and 1 with a linespeed of 70mph or more not previously included in SIN104.

o Full-depth facing switches in Track Category 2 with a linespeed of 100mph or more.

o Switch diamonds with full depth switches in:

o Track Categories 1A and 1 with a linespeed of 70mph or more

o Track Category 2 with a linespeed of 100mph or more.

This SIN excludes Bullhead switches.

Background and purpose

SIN 101 included the inspection of all full depth switches in running lines to record various parameters relating to the condition and set-up of fixed stretcher bar assemblies.

SIN 101 also mandated remedial works to be carried out as specified in Charts 9.1, 9.2 and 9.3 therein. The remedial works specified in SIN 101 addressed higher risk conditions linked with component defects, Flange Back Contact (FBC) and/or Residual Switch Opening (RSO) associated with switch flexure.

SIN104 required the free wheel passage to be corrected and where appropriate stretcher bars to be changed for new 'Yellow' bars to RE/PW/721 on full depth switches with fixed stretcher bars in Track Categories 1A and 1 with a linespeed of 90mph or more.

The purpose of this SIN is to extend the scope of the remedial work carried out under SIN104 to a wider population of switches.

Issue 1 of NR/L3/TRK/1202 (and consequently SIN104) was restricted to AV to HV Vertical and A to G inclined switches, including those that form part of a larger layout (e.g. crossovers, tandems, scissors and double junctions) manufactured from BS113A rail.

Issue 2 of NR/L3/TRK/1202 has a wider scope that includes switches manufactured from BR109 and BS110A rail, and slips and switch diamonds manufactured from BR109, BS110A, BS113A and CEN56 rail.

As the scope of this SIN includes any S&C manufactured from BR109 or BS110A rail that was not included in SIN104 full application of this SIN requires the implementation of NR/L3/TRK/1202 issue 2.