scope:

This SIN applies to all switches that fall within the phases of work shown in section 2.1 and the scope of sections 2.2 & 2.3.

Scope - Phases of work

There are two phases of work within this SIN as detailed in the table below. Due to late availability of shallow depth designs of tubular stretcher bar it is acceptable to substitute phase 2 switches for phase 1 switches to achieve the overall volume of fitments required to complete phase 1.

Phase 1

Phase 1 shall be completed by 31^st December 2015. Phase 1 is complete when the volume of completed installations (which can include phase 2 switches) matches the volume identified in the scope of 1a, 1b and 1c.

Scope of this SIN - Design of S&C

The Tubular stretcher bar is compatible with the following designs of switch:

1. Vertical Full Depth

(manufactured from BS110A, BS113A or CEN56 rail) - plain leads (switch sizes AV to HV) in turnouts, crossovers, double junctions, scissors crossovers and switch diamonds.

2. Vertical Shallow Depth

(manufactured from BS113A/UIC54B or CEN56/CEN54E1A1 rail) - plain leads (switch sizes BVS to HVS) in turnouts, crossovers, double junctions, scissors crossovers and switch diamonds.

3. RT60

Plain leads (switch sizes C to G) in turnouts, crossovers and double junctions.

4. BR Inclined

(manufactured from BR109lb, BS110A, BS113A or CEN56 rail) - plain leads (switch sizes A to G) in turnouts, crossovers, double junctions, scissors crossovers and switch diamonds.

Scope of this SIN - Type of Points Operating Equipment

The Tubular stretcher bar is compatible with the following types of POE.

1. Rail Point Clamp Lock (Mk1, Mk2 & In-Bearer) - within scope of the SIN where fitted to switch diamonds.

2. HW (family) - excluding points fitted with Torsional Drives

3. Type 63 - excluding points fitted with Torsional Drives

Other types of POE (not listed) require testing to confirm compatibility with the tubular stretcher bar and will remain outside the scope of the SIN.

Purpose

This SIN covers the installation of the new tubular stretcher bar in existing switches as part of a programme to reduce risk.

The tubular stretcher bar has been developed to replace both 'fixed' and 'adjustable' stretcher bars in new and existing installations.

The majority of switches on Network Rail infrastructure use either 'fixed' full depth stretcher bars (known as 'black' or 'yellow' bars) or 35mm square 'adjustable' bars (often referred to as an '814 or 'adjustable' bar).

Fixed and adjustable stretcher bars are known to suffer from accelerated failure when subjected to repeated flange back contact or high drive forces usually as a result of overdriving with electro-mechanical Point Operating Equipment (POE). The tubular stretcher bar has been designed to eliminate these failures and reduce risk.

The more modern types of POE such as Hy-drive and HPSS have their own designs of stretcher bars and are outside the scope of this SIN. NR/L2/TRK/6100 specifies the use of the tubular stretcher bar in S&C renewals and maintenance tasks such as the replacement of half sets of switches, re-gauging or when replacing defective stretcher bars.