MTM DESIGN PRACTICE NOTE USE OF GUARD RAILS

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Janis Wilkinson
5 years ago
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Approval Amendment Record Approval Date Version Description 24/08/2016 1 Initial issue

1 Approval Amendment Record Approval Date Version Description 24/08/ Initial issue PRINTOUT MAY NOT BE UP-TO-DATE; REFER TO METRO INTRANET FOR THE LATEST VERSION Page 1 of 6

2 Table of Contents 1. Purpose Scope Background The Issue Reference Documents Functional Requirements General Requirements Technical Requirements Guard Rail Assembly Positioning of Guard Rails Signalling and Electrical Requirements... 6 PRINTOUT MAY NOT BE UP-TO-DATE; REFER TO METRO INTRANET FOR THE LATEST VERSION Page 2 of 6

3 1. Purpose The purpose of this Design Practice Note (DPN) is to outline MTM requirements for the design and installation of guard rails, in accordance with AS 7640 Rail Infrastructure Rail Management. 2. Scope The DPN applies to all new infrastructure intended to be managed by MTM, where a risk assessment has identified the need to provide close containment of a derailed vehicle on a plain line track section. 3. Background Due to the tendency to construct new track alignments offline to the side of an existing corridor or above existing ground level, the operating railway is sometimes moved into closer proximity to existing public, residential and commercial areas. MTM has identified a need to consider the provision of derailment containment devices on some new track alignments in order to minimise the likelihood of a derailed vehicle damaging lineside infrastructure or falling from a structure. 4. The Issue Existing MTM requirements detailed in L1-CHE-INS-026 specifies the use of derailment kerbs or deflection barriers on underbridges. There may be a requirement for additional close containment at other locations such as on embankments, bridge approaches, or adjacent to high-risk infrastructure. The RISSB document AS 7640 Rail Infrastructure Rail Management outlines the high-level function and requirements for guard rails. MTM currently has no guidelines for the application of AS 7640 with regards to the use of guardrails for new installations. 5. Reference Documents The following standards and documents have been referenced in the development of this DPN. AS 7640 AS L0-SQE-PRO-031 L1-CHE-INS-026 Rail Infrastructure Rail Management Railway Track Materials Part 1: Steel Rails Enterprise Risk Management Procedure Design Practice Note: Derailment Control on Underbridges MTPR Welded Track Management Manual Chapter 8 Laying Rail Bolted, Welded and LWR NIST-2650 TA 0125 Use and Laying of Rail MTM Type Approval: Austral Full Depth Guardrail Sleeper and Guardrail Assembly In the event of an inconsistency between this DPN and the referenced material, the designer shall seek clarification from the MTM Chief Engineer. PRINTOUT MAY NOT BE UP-TO-DATE; REFER TO METRO INTRANET FOR THE LATEST VERSION Page 3 of 6

4 6. Functional Requirements The design and installation of guard rails shall be in accordance with the requirements listed in this DPN. For new track construction, the requirement to install guard rails shall be determined through a risk assessment process. The location of the new track alignment in relation to an identified hazard shall be assessed to determine if there is adequate restraint of a derailed vehicle, so far as is reasonably practicable, when using existing control measures and considering similar occurrences on the MTM network. Guard rails may be selected to provide further containment if deemed necessary. Examples of where/how this may occur include: Constructing the railway on a raised structure immediately adjacent to residential or commercial properties, areas used by the public, etc. where there is a risk of a vehicle falling from height at a near-vertical angle; Transitioning between different track forms, where there may be uneven settlement; or Tracks adjacent to high-risk assets such as pipelines and other services. The use of guard rails shall be limited to the extent of the hazard plus the necessary approach lengths outlined in section Excessive use of guard rails must be avoided in order to minimise impacts on future maintenance and renewal activities. Guard rails must not be used in lieu of collision or anti-snag protection requirements for existing or new structures. Guard rails are not required for existing or reconstructed track which is generally unchanged from its established alignment, unless a specific risk has been identified and installation has been deemed necessary by the Office of the Chief Engineer. Any existing guard rail assemblies are not subject to the requirements of this document. During track reconstruction, existing assemblies should be upgraded to comply with this DPN, where reasonably practical. 6.1 General Requirements The design shall demonstrate that all controls have been adopted, so far as is reasonably practicable, to ensure the use of guard rails as the primary derailment control device, or as part of the derailment control system, meets the following primary requirements: Keeps derailed or derailing bogies/wheels tracking parallel and in close proximity to the running rails, with the axles parallel to the plane of the running rails; Increase the likelihood that a derailed train will be kept upright and within gauge of the track it was travelling on; and Limits potential damage to rolling stock and lineside infrastructure. Guard rails may be considered for use on underbridges, in addition to derailment kerbs or deflection barriers, to form part of the derailment control system. Guard rails must not be used as the only derailment control device on underbridges. In other locations, including on approach to underbridges, guard rails may be used as the only form of derailment control if deemed sufficient. PRINTOUT MAY NOT BE UP-TO-DATE; REFER TO METRO INTRANET FOR THE LATEST VERSION Page 4 of 6

5 Guard rails shall only be used in conjunction with type approved concrete sleepers, or a form of direct fix track. Guard rails must be suitably insulated to suit the requirements of the signalling and electrical infrastructure in which they are located. Alternative systems which can provide the same functionality and performance as guard rails but are more suitable to a certain track system (such as a concrete kerb in conjunction with direct fix track), may be suitable subject to acceptance by MTM Head of Engineering Track and Structures. 6.2 Technical Requirements The designer shall provide design drawings to detail the installation extents and setout requirements to provide sufficient protection of the identified hazard. The Design shall be accepted by MTM Engineering prior to installation Guard Rail Assembly New guard rail assemblies shall use type approved equipment and the design shall demonstrate compliance with the following requirements: Each guard rail assembly shall consist of a guard rail nose set connected to two guard rails located between the running rails. A single guard rail is not deemed adequate; For bi-directional train running, a guard rail nose set shall be installed at each end of the guard rail installation. For uni-directional train running, a guard rail nose set shall be installed on the approach side of the guard rail installation; Guard rail shall be new rail manufactured to AS , or recycled rail subject to testing and prior acceptance by the MTM Head of Engineering Track and Structures; Guard rail section shall be the same as the running rail, or no greater than one section size less; The top of the guard rail shall be no higher than the adjacent running rail and no more than 50mm below the running rail; The minimum clear width between the guard rail and the running rail (face to face) shall be 380mm (+20/-0), measured 16mm below the top of rail; Guard rail size shall be consistent throughout the length of any installation; Guard rail section shall be secured at each sleeper (or equivalent spacing on direct fix track forms); The guard rail nose shall be splayed at 30 degrees to the track centreline and form a point at the centreline of the track which would not act to obstruct a derailed wheel, but guide it towards the running rail; Guard rails shall be fastened using a type approved assembly. If pandrol e-clip fastenings are adopted, left and right hand clips shall be alternated longitudinally to reduce the risk of a derailed train dislodging consecutive clips, and PRINTOUT MAY NOT BE UP-TO-DATE; REFER TO METRO INTRANET FOR THE LATEST VERSION Page 5 of 6

6 Guard rails shall be connected by bolted joints consisting of 4 hole fishplates as a minimum. They shall be installed in accordance with the bolted rail requirements detailed in MTPR Welded Track Management Manual Chapter 8 Laying Rail Bolted, Welded and LWR, subject to the following specific amendments: o o o Positioning of Guard Rails 4 hole joints are considered sufficient for use on all guard rail sizes; The diameter of the holes in the rail shall be increased from 30mm to 31mm. Fishplate hole sizes are to remain to standard, and The heads of all bolts within a joint shall be to the outside of the guard rail (nearest to the running rail), to reduce the risk of damage by a derailed train; The design of the guard rail position must provide adequate protection for the extent of the identified hazard. Guard rails shall extend for the full length of the hazard they are intended to protect and beyond the hazard by a minimum distance of 20 metres. On uni-directional and bi-directional tracks, they shall extend in front of the hazard they are protecting, by the greater value of: The distance a train can travel in 2.5 seconds at maximum line speed, or 20 metres. Guard rail nose assemblies may be installed on curved track with a radius of 800m or greater. If the radius is less than 800m, guard rails must be extended into tangent track, unless otherwise agreed by the MTM Head of Engineering Track and Structures Guard rail nose assemblies must not be located on or within the following: Cant transitions; Level / Pedestrian crossings; Hi-rail access pads, and Turnouts and crossing work Signalling and Electrical Requirements The design must provide details for the insulation requirements identified by the signalling and electrical engineers. As a minimum, where any part of the guard rail is in a track circuited area or adjacent to a TPWS aerial, a single insulated joint shall be installed between the guard rail nose assembly and at least one of the adjacent guard rails. Where required, insulated joints shall be type approved assemblies. Where it is necessary to install an insulated joint, it must not replace a bolted joint that is required for expansion. PRINTOUT MAY NOT BE UP-TO-DATE; REFER TO METRO INTRANET FOR THE LATEST VERSION Page 6 of 6

MTST TRACK DESIGN AND CONSTRUCTION

MTST TRACK DESIGN AND CONSTRUCTION Engineering Standard Track and Civil Version: 2 Issued: November 2016 Owner: Chief Engineer Approved By: Phil Ellingworth Chief Engineer PRINTOUT MAY NOT BE UP-TO-DATE; REFER TO METRO INTRANET FOR THE