VRIOGS 010.7 RevA - Public Transport Victoria

16 VRIOGS 010.7 Revision Aprotection is maintained to the extent required by VRIOGS 012.1 Standard forSignalling Design and Documentation.6.3.1 Single Rail1. The signalling rail of single rail track circuits shall be bonded to the samestandards as the traction rail with exception of series bonds, which shall not beused or rated for traction return current.2. Transpositions, where insulated joints and bonding are provided to swap thetraction rail of a single rail track circuit between the Up and Down rails of onetrack circuit, or between contiguous track circuits, are not permitted exceptsubject to prior specific individual approval by the Infrastructure Manager.Where a traction transposition is installed, the number and size of cables shallbe the same as are used for impedance bond neutral connections in the samearea.6.3.2 Double Rail1. Double rail track circuits use both rails for traction return and it is important toensure that traction is balanced for the correct operation of impedance bondsand rack circuits.2. For the purpose of improving broken rail detection in double rail track circuitsit is preferable to use additional receivers rather than full parallel bonding overpoints and crossing layouts.3. Rails connected by full parallel bonding shall not exceed 50 metres in lengthand the track circuit parameters shall be specifically checked to conform theycomply with the manufacturer’s recommendations.4. All parallel bonds shall be at least duplicated at each connection point.6.3.3 Bonding at Points and Crossings1. On main lines, bonding of points shall be arranged to provide maximumbroken rail detection of both rails in the main line and maximum assurance oftrain detection in the turnout. Series bonding is the bonding method that is tobe utilised and refer to Plan STD_G0061 Track Circuit Series BondingArrangement.2. On double rail track circuits this shall be achieved preferably by the use ofseparate receivers on each leg of the turnout.3. Where this is not practicable, special parallel bonding arrangements for theturnout leg of the track circuit shall be applied.4. On single rail track circuits, series/parallel bonding shall be used over pointsin preference to full parallel bonding, subject to the requirement that sufficientrails be available for traction current return.5. Where the preferred methods are not practicable, for instance in crossoversbetween main line tracks, double rail track circuits with full parallel bondingover points may be used with the approval of the Infrastructure Manager.6. Insulation of points and crossings shall be arranged to place insulated jointsin the less-used path as far as possible.7. Bonding shall be arranged to minimise, as far as practicable, the length of allparallel and series bonds.NOTE: This document is controlled only when viewed on the DOT Engineering Standards website.Any other copy of this document is uncontrolled, and the content may not be current.