scope:

Introduction

The following statement appears in paragraph 4 of section 5.3.1 of the Network Rail EBI Track 200 Application Manual 11761/A010 [1]: 'There is no cross bonding (direct or indirect) between the respective lines, except at the site of Txs of the same frequency, which shall therefore be aligned in parallel. (This requirement may prove to be prohibitive on existing electrified lines, but alternative proposals may be acceptable, subject to safety assessment.)'. For completeness, the full text of section 5.3.1 is given in Appendix A. The validity of this requirement has been questioned by signalling designers and testers at Network Rail. The Crossrail Project have analysed non compliances from historic installations in their area and have documented them in Technical Assessment WRR5I_ESG_REP_AMA_000055 A01.pdf [3].

This document is supported by the following referenced sketches:

• 6204m to 8km Sketch 1 - Version 2.pdf [4]
• 8km to 10km Sketch 2 - Version 2.pdf [5]
• 10km to 12.500km Sketch 3 - Version 3.pdf [6]
• 12.500km to 15km Sketch 4 - Version 4.pdf [7]
• 15km to 17.5km Sketch 5 - Version 3.pdf [8]
• 17.5km to 20.0km Sketch 6 - Version 3.pdf [9]

As a result of this assessment a meeting was convened to review the scenarios where bonding between parallel track circuits of the same frequency might give rise to false energisation of a Receiver. This document contains a record of the review meeting, and a summary of its recommendations.