GK/GN0644. Guidance on Permissive Working. Rail Industry Guidance Note for GK/RT0044

Transcription

1 GN Published by: Block 2 Angel Square 1 Torrens Street London EC1V 1NY Copyright 2014 Rail Safety and Standards Board Limited GK/GN0644 Issue Two December 2014 Rail Industry Guidance Note for GK/RT0044

2 Issue record Issue Date Comments One June 2013 Original document. Published with GK/RT0044 issue two Permissive Working, to provide rationale and guidance on the requirements in that document. Two December 2014 Amended requirements to signalling controls in 3.2 and 4.2, with new supporting guidance, to address proposal 12/031 allowing the calling-on movement authority to be displayed when the approaching train is within 100 m of the signal. References have also been updated. Amended or additional parts and/or sections of revised pages have been marked by a vertical black line in the adjacent margin. Superseded documents Uncontrolled When Printed The following Rail Industry Guidance Note is superseded, either in whole or in part as indicated: Superseded documents GK/GN0644 issue one Guidance on Permissive Working Sections superseded Date when sections are superseded All 07 March 2015 GK/GN0644 issue one, ceases to be in force and is withdrawn as of 07 March Supply The authoritative version of this document is available at Uncontrolled copies of this document can be obtained from Communications,, Block 2, Angel Square, 1 Torrens Street, London EC1V 1NY, telephone or enquirydesk@rssb.co.uk. Other Standards and associated documents can also be viewed at Page 2 of 27

3 Contents Section Description Page Part 1 Introduction 4 G 1.1 Purpose of this document 4 G 1.2 The structure of this document 4 G 1.3 Copyright 4 G 1.4 Approval and authorisation of this document 4 Part 2 Guidance on Compatibility Requirements for Permissive Working 5 G 2.1 Compatibility between systems for permissive working and train operations 5 G 2.2 Specific factors for passenger train movements 6 G 2.3 Specific factors for freight train movements 7 Part 3 Guidance on Requirements for Movements Involving Passenger Trains 8 G 3.1 Provision of signals 8 G 3.2 Signalling controls 9 Part 4 Guidance on Requirements for Movements Involving Freight Trains 11 G 4.1 Provision of signals 11 G 4.2 Signalling controls 11 Part 5 Application of this Document Application infrastructure managers Application railway undertakings Health and Safety Responsibilities 14 Appendices Appendix A Factors for Consideration in the Assessment of Compatibility for Permissive Passenger Working 15 Definitions 25 References 27 Page 3 of 27

4 Part 1 G 1.1 G G 1.2 G G G G 1.3 G G G G 1.4 G Introduction Purpose of this document This document gives guidance on interpreting the requirements of Railway Group Standard Permissive Working. It does not constitute a recommended method of meeting any set of mandatory requirements. The structure of this document All requirements from Railway Group Standard GK/RT0044 are reproduced with a grey background in this document. Guidance is provided as a series of sequentially numbered clauses prefixed G immediately below the greyed text to which it relates. Specific responsibilities and compliance requirements are laid down in the Railway Group Standard itself. Copyright Copyright in the Railway Group documents is owned by Rail Safety and Standards Board Limited. All rights are hereby reserved. No Railway Group document (in whole or in part) may be reproduced, stored in a retrieval system, or transmitted, in any form or means, without the prior written permission of Rail Safety and Standards Board Limited, or as expressly permitted by law. members are granted copyright licence in accordance with the Constitution Agreement relating to Rail Safety and Standards Board Limited. In circumstances where Rail Safety and Standards Board Limited has granted a particular person or organisation permission to copy extracts from Railway Group documents, Rail Safety and Standards Board Limited accepts no responsibility for, nor any liability in connection with, the use of such extracts, or any claims arising therefrom. This disclaimer applies to all forms of media in which extracts from Railway Group Standards may be reproduced. Approval and authorisation of this document The content of this document was approved by Control Command and Signalling (CCS) Standards Committee on 18 September G This document was authorised by on 21 October Page 4 of 27

5 Part 2 G 2.1 G G Guidance on Compatibility Requirements for Permissive Working Compatibility between systems for permissive working and train operations The design of new or altered arrangements for rolling stock, facilities or operation for permissive passenger (PP) or permissive freight (PF) working shall be assessed to establish compatibility with the infrastructure and rolling stock authorised to operate over the route. The rationale for this requirement is that changes to the infrastructure, rolling stock or method of operation without a compatibility check could result in unintended consequences, such as use of longer trains with insufficient room to be accommodated in station platforms, or the introduction of permissive working arrangements that are incompatible with the signalling provided. Examples of changes to PP or PF facilities or operation include: a) Timetable alteration. b) Change of type / length of trains. c) Change of length of vehicles where track circuits are used to detect available space, or number of axles per vehicle where axle counters are used to indicate number of vehicles. d) Change of operating procedures or instructions. e) Modification of track and / or signalling. f) Change in stopping positions. g) Change in station lighting or furniture affecting PP or PF. G G GE/RT8270 sets out the requirements and responsibilities for the assessment of compatibility between rolling stock and infrastructure assets, including control, command and signalling equipment and their operations. It sets out the arrangements by which the assessment of compatibility is undertaken and identifies those responsible for managing that assessment. GK/RT0044 sets out specific technical requirements to achieve compatibility of systems for signalling passenger trains onto an occupied line with train operations The assessment for PP working shall consider the factors set out in Appendix A. G G The rationale for the requirement to assess the factors set out in Appendix A is that they can affect the safe operation of a PP working facility. Freight trains and passenger trains should not occupy the same signal or block section at the same time. The rationale for segregating freight trains and passenger trains is that the braking characteristics of long freight trains are significantly different from those of passenger trains. Also, their coupling systems are liable to be different. Freight trains and passenger trains should only couple in exceptional situations. Automatic route setting (ARS) programs should be written to avoid freight trains and passenger trains being signalled into the same signal or block section at the same time. Page 5 of 27

6 G G 2.2 Platform lines signalled for permissive working can be used on different occasions by either passenger or freight trains, but not by passenger trains and freight trains at the same time. Specific factors for passenger train movements Facilities for signalling a passenger train onto an occupied line shall only be provided where all of the following apply: a) It is a platform line. b) The purpose is for platform sharing and / or joining trains. c) There is no reasonably practicable alternative method of working which presents less risk. G The rationale for allowing permissive working is to: a) Realise the operational benefits of being able to join trains, share platforms or attach vehicles. And b) Achieve passenger convenience benefits, including passengers not having to use bridges, stairs or subways. G G G Allowing trains to join or to share a platform facilitates the working of stations where the number of platforms is restricted. The rationale for restricting permissive working of passenger trains to platform lines is to avoid such trains being stopped, for example, for joining at locations where passengers cannot alight should any problem arise. Such situations are likely to have performance disadvantages, and passengers may be alarmed or frustrated if a train is stopped other than at a station. The rationale for using methods for berthing trains that avoid permissive working is to enable each train to be fully protected by the signalling system. Examples of alternative methods for avoidance of permissive working of passenger trains include: a) Use of empty platforms. b) Provision of mid-platform signals. c) Use of non-adjacent platforms. d) Timetabling trains to use platforms sequentially. e) Forming complete trains in sidings before entering service. Methods c) and d) are suitable only where passenger interchange is not required between the two services. G A method that is reasonably practicable at one station may not be so at another. Page 6 of 27

7 G 2.3 Specific factors for freight train movements Facilities for signalling a freight train onto an occupied line shall be provided where all of the following apply: a) There is no reasonably practicable alternative method of working which presents less risk. b) Permissive working is confined to freight trains. G G The rationale for PF working is to realise operational benefits in enabling freight trains to follow one another, for example when awaiting acceptance into depots or yards, or when following along a goods line, and for locomotives running round freight trains. Alternative methods for avoidance of PF working include: a) Provision of intermediate signals. And b) Use of multiple (reception) lines. G It is not necessary for the first train on a PF line to be stationary for a second train to be admitted to the section. Page 7 of 27

8 Part 3 G 3.1 Guidance on Requirements for Movements Involving Passenger Trains Provision of signals Movement of the second train from the protecting signal shall be controlled by either: a) A position light signal associated with a main signal. Or b) A semaphore shunting signal If the second train does not convey passengers, but for the purposes of this document is included within the definition of a passenger train, it is also permissible to control the movement by either: a) A position light shunting signal. Or b) A semaphore shunting signal. G G G The rationale for using distinctive signals for permissive moves is that they are recognised by drivers to proceed cautiously on the understanding that there is a stationary train ahead before reaching the next signal. This requires that trains conveying passengers are signalled by running signals having main aspects. Other trains, for example empty coaching stock and light engines, may approach an occupied line by means of a subsidiary signal at the exit from a siding or depot. GK/RT0045 sets out the requirements for the form of the signals and the provision of associated route indicators The distance between the protecting signal and the nearest end of the first train shall be minimised, as far as reasonably practicable, without compromising other requirements for signal positioning. G The rationale for keeping the distance between the protecting signal and the rear of the first train (which is the furthest point to which the second train may need to run) as short as possible is: a) To reduce the time available in which the driver might make an error, for example forgetting that a calling-on aspect had been displayed at the protecting signal. And b) To minimise the distance available for the second train to accelerate to a speed and so be travelling too fast into the platform to be able to stop short of the first train. G The importance of determining the point of visibility is so that the driver of the second train has a fixed target on which to base his / her braking technique. Page 8 of 27

9 G G 3.2 The location of the protecting signal is dictated by many factors, particularly optimum signal spacing, aspect sequence and signal sighting. Where the optimum location of the protecting signal would compromise the standard four-aspect sequence, one possible solution could be the provision of a closing-up signal and use of a nonstandard (consecutive single yellow) aspect sequence, as set out in GK/RT0045. Signalling controls The protecting signal shall display a proceed aspect for a permissive movement if all the following conditions are satisfied: a) The platform starting signal ahead of the first train is at danger. b) The line is clear from the protecting signal to the nearest danger point where the end of the first train may legitimately be positioned. c) The first train has completed its movement and can be assumed to be at a stand. d) The second train: i) Is within 100 m of the protecting signal. And ii) Has reached the point at which the calling-on aspect and any associated route indicator is readable. G G G G G G The rationale for maintaining the platform starting signal at danger while a permissive move is being made into the platform is to avoid movement of the first train, so giving the second train a fixed end of movement authority. Also, the first train (if allowed to move) may stop unexpectedly, thereby increasing the possibility of the second train colliding with it. It also eliminates the possibility of the driver of the second train reading through to a proceed aspect on the platform starting signal. The rationale for not displaying the calling-on movement authority until the train is within 100 m from the protecting signal is that the speed of the train at that distance is consistent with the driver transitioning to the permissive movement and the train then being driven on sight. The flexibility provided by the calling-on proceed aspect being given when the train is within 100 m from the protecting signal enables operational efficiencies to be realised. For example, for trains approaching a permissive section where the signal is on a rising gradient it might be operationally beneficial for the proceed aspect to be given to maximise the available train momentum which reduces the acceleration that would be needed in negotiating the rising gradient. The distance of the train from the protecting signal when the permissive move proceed aspect is given should be addressed in the permissive movement risk assessment. In obeying the position light aspect, the driver of the second train takes over responsibility from the infrastructure manager for the prevention of a collision with the first train. Notwithstanding the instructions to the driver, it is good practice to prove train detection clear between the protecting signal and the commencement of the platform. This reduces the likelihood of the second train having to stop over pointwork, thus causing operating problems. Page 9 of 27

10 3.2.2 The platform starting signal which controls the movement of the first train shall not display a proceed aspect until the second train has completed its movement and can be assumed to be at a stand. G G The rationale for not allowing the first train to move until the second train has stopped is to preserve the fixed stopping point for the second train. If the first train is allowed to move while the second train is approaching, there is a risk of a collision if it stops for any reason. The rationale for holding the platform starting signal at danger until the second train has stopped is to maintain the conditions that existed when the protecting signal was cleared for the second train. Page 10 of 27

11 Part 4 G 4.1 Guidance on Requirements for Movements Involving Freight Trains Provision of signals The movement of the second train from the protecting signal shall be controlled by one of the following: a) A position light signal associated with a main signal. b) A semaphore subsidiary signal associated with a main signal. c) A position light shunting signal. d) A semaphore shunting signal. G G G 4.2 The rationale for using distinctive signals for permissive moves is that they are recognised by drivers as indicating a need to proceed cautiously, on the understanding that there may be a stationary train ahead before reaching the next signal. GK/RT0045 sets out the requirements for the form of the signals and the provision of associated route indicators. Signalling controls The protecting signal controlling the entrance to the permissive line shall not display a proceed aspect for the movement unless both of the following conditions are satisfied: a) The line is clear from that signal to the nearest point where the end of the first train may legitimately be positioned. b) The second train: i) Is within 100 m of the protecting signal. And ii) Has reached the point at which the calling-on aspect and any associated route indicator is readable. G G G The rationale for allowing PF working is to allow following trains to close up along a goods line, loop or reception line. As such, intermediate signals should be allowed to clear, irrespective of a permissive movement taking place from the signal in rear. The rationale for not displaying the calling-on movement authority until the train is within 100 m from the protecting signal is that the speed of the train at that distance is consistent with the driver transitioning to the permissive movement and the train then being driven on sight. The flexibility provided by the calling-on proceed aspect being given when the train is within 100 m from the protecting signal enables operational efficiencies to be realised. For example, for trains approaching a permissive section where the signal is on a rising gradient it might be operationally beneficial for the proceed aspect to be given to maximise the available train momentum which reduces the acceleration that would be needed in negotiating the rising gradient. The distance of the train from the protecting signal when the permissive move proceed aspect is given should be addressed in the permissive movement risk assessment. Page 11 of 27

12 G G G G Isolated colour light distant signals should be avoided if they are likely to mislead a driver proceeding under the authority of a calling-on aspect into believing that the line is clear. Automatic Warning System (AWS) equipment should be controlled to give a caution indication when the line is occupied between the magnet and the associated signal. Although the meaning to the driver Proceed, prepare to stop short of any obstruction applies to the whole route, train detection should prove the route clear up to the location where PF working commences. This is because it would be inappropriate to allow a train to enter a route where it would have to stop in a position where it would foul lines that are not included in the portion of route where PF working applies. As the requirements for PF working are less stringent than for PP working, it is not necessary for the signal ahead of the permissive route to be maintained at danger; this allows following trains to progress through several permissive sections. However, to minimise the possibility of a train having to stop foul of other lines, the extent of permissive working should not include points and crossings leading to the loop. Page 12 of 27

13 Part 5 Application of this Document 5.1 Application - infrastructure managers Scope The content of this document applies to circumstances in which trains are admitted onto occupied lines by the use of fixed lineside signals The requirements of this document apply to all work that affects controls for signalling or operation of a train onto an occupied line The requirements of this document apply immediately Exclusions from scope This document does not apply to: a) Shunting movements into, or entirely within, sidings. b) The situation where the second train makes a further movement after it has come to a stand on completion of the movement authorised by the fixed signal General compliance date for infrastructure managers This Railway Group Standard comes into force and is to be complied with from 07 March After the compliance date, or the date by which compliance is achieved, if earlier, infrastructure managers are to maintain compliance with the requirements set out in this Railway Group Standard. Where it is considered not reasonably practicable to comply with the requirements, authorisation not to comply should be sought in accordance with the Railway Group Standards Code Exceptions to general compliance date There are no exceptions to the general compliance date specified in for infrastructure managers. 5.2 Application - railway undertakings Scope The content of this document applies to all circumstances in which trains are admitted onto occupied lines by the use of fixed lineside signals The requirements of this document apply to the operation of trains undertaking permissive movements Exclusions from scope Parts 3 and 4 do not apply to railway undertakings This document does not apply to: a) Shunting movements into, or entirely within, sidings. b) The situation where the second train makes a further movement after it has come to a stand on completion of the movement authorised by the fixed signal. Page 13 of 27

14 5.2.3 General compliance date for railway undertakings This Railway Group Standard comes into force and is to be complied with from 07 March After the compliance date, or the date by which compliance is achieved, if earlier, railway undertakings are to maintain compliance with the requirements set out in this Railway Group Standard. Where it is considered not reasonably practicable to comply with the requirements, authorisation not to comply should be sought in accordance with the Railway Group Standards Code Exceptions to general compliance date There are no exceptions to the general compliance date specified in for railway undertakings. 5.3 Health and safety responsibilities Users of documents published by are reminded of the need to consider their own responsibilities to ensure health and safety at work and their own duties under health and safety legislation. does not warrant that compliance with all or any documents published by is sufficient in itself to ensure safe systems of work or operation or to satisfy such responsibilities or duties. G There is no guidance associated with Part 5. Page 14 of 27

15 Appendix A Factors for Consideration in the Assessment of Compatibility for Permissive Passenger Working The use of this appendix is mandatory Uncontrolled When Printed The factors set out below shall be considered in the assessment of compatibility for permissive passenger (PP) working. This appendix comprises three topic areas: A.1 to A.3, which address respectively the number of permissive moves, the likelihood of the second train failing to stop short of the first train and the consequences of a collision between the two trains. G A.1 Factors affecting frequency of permissive moves A.1.1 Number and type of permissive moves. A.1.2 Availability of alternatives to permissive moves. G A.1.1 G A.1.2 The rationale for determining the frequency of permissive moves for each route is to enable the overall risk from permissive moves at a location to be determined. Sections A.2 and A.3 can be used to assess the risk from a single permissive move for a particular route. The frequency of moves per route can then be used to scale the risk from a single permissive move on each route appropriately. These can then be combined to determine an overall level of risk from permissive moves for the location. The particular requirements at each station should be defined to enable appropriate signalling facilities to be installed. Requirements include: a) Timetabled joining of trains. b) Timetabled platform sharing. c) Occasional use of permissive working for joining trains and / or platform sharing during timetable perturbations. G A.1.3 G A.1.4 The rationale for assessing the alternatives to permissive working is that it may be possible to avoid platform sharing or stabling and thus eliminate the risk. The provision of mid-platform signals may enable permissive working at some locations to be avoided. Permissive working may be used to enable: a) Joining trains that then continue their journeys as a combined train. a) Trains sharing a platform, for example to permit passenger interchange or for timetabling purposes. b) Admission of trains to platforms that are partially occupied by stabled trains. This is more likely at terminal platforms or bays. c) A reduction in the likelihood of slips, trips and falls by passengers not having to use footbridges or subways to make connections. Page 15 of 27

16 G A.2 G A.2.1 Factors affecting the likelihood of the second train failing to stop short of the first train Introduction A This section supports industry in identifying and assessing the physical features of the route, and features of the train and timetabling which may impact on driver performance, or reduce the likelihood that they can recover from errors. It also covers signaller error. For the driver carrying out the permissive movement these factors have been grouped into key areas which require assessment from the protecting signal to the stopping point behind the first train: a) Visibility and readability of the protecting signal for the driver of the second train. The physical features of the protecting signal and surrounding location which impact on the reliability of the driver correctly interpreting and acting upon it. b) Driveability of route for the driver of the second train. Physical features (for example, gradients, complexity) of the route from the permissive signal to the stopping point which could impact on the performance of the driver of the second train. c) Visual factors throughout the movement of the second train. Visual features (for example, sunlight, tunnels) of the route from the permissive signal to the stopping point which could impact on the performance of the driver of the second train. d) Readability of the stopping cues for the driver of the second train. Assessment of the stopping cues (particularly the end of the first train) which could impact on the performance of the driver of the second train. e) Factors affecting braking on the approach to the stopping point for the second train. For the portion of the route where the second driver will be braking to stop in order to complete the movement, features (for example, gradients or rail contamination) which could impact on the performance of the train braking and the driver's ability to stop the train. f) Driver factors throughout the movement of the second train. Factors which are not features of the route (for example, frequency of experience of permissive moves or additional tasks for the driver of the second train) which could impact on their performance. g) Signaller error. Human errors by the signaller during the set-up and authorisation of a permissive move. A A These groupings shall not be assessed in isolation of each other, for example visual factors such as ambient illumination at the platform will impact on the readability of the nearest end of the first train. The risk assessment shall include input from drivers familiar with permissive working, particularly in respect of the locations being assessed and the types of rolling stock involved. G A.2.2 Visibility and readability of the protecting signal for the driver of the second train A.2.2 Visibility and readability of the protecting signal for the driver of the second train: Page 16 of 27 a) The protecting signal not having a miniature route indicator (MARI) for the calling-on route.

17 b) The appearance of the signal (including route indicators etc). c) Sighting time for the signal. d) Other signals which the driver can see on the approach to the protecting signal. G A The rationale for subsidiary routes from main signals requiring miniature route indicators (as set out in GK/RT0045) is to provide an additional safeguard to drivers in distinguishing that a calling-on route, as opposed to a main route, has been set from the protecting signal, to reinforce drivers understanding that the move being undertaken is: a) Permissive. And b) To a clearly identified platform. Incorrect interpretation of the signal can lead directly to the driver not realising that the train has been given a permissive movement authority. G A The rationale for using a miniature route indicator (see A.2.2a)) is because: a) The train has been timed to a stand at the protecting signal and is therefore close to the signal before any movement authority can be displayed. And b) The route indicator is usually proved in the aspect, so should be illuminated before the signal can clear. G A G A G A.2.3 A driver seeing the same route indicator illuminated that would be displayed by a main route could assume that a main class movement authority has been given. GK/RT0045 is applicable to new installations but a significant number of locations exist that still display position light junction indicators or standard alphanumeric route indicators in association with calling-on routes. The requirements for the provision of lineside signals are set out in GK/RT0045 and the arrangements for signal sighting (see A.2.2b) and A.2.2c)) are set out in GE/RT8037. The rationale for considering other signals that may be displaying movement authorities (see A.2.2d)) is that drivers could read across to signals applicable to parallel lines that may be displaying movement authorities. (This is particularly the case on the approach to stations where several lines are signalled for bi-directional working, which results in multiple signals side by side on the same gantry.) Driveability of route for the driver of the second train A.2.3 Driveability of route for the driver of the second train: a) Distance between the calling-on signal and the stopping point or visual stopping cues. b) Number of possible signalled routes leading to the station. c) Number of alternative routes from the protecting signal to the platform(s). d) Curvature of the track. e) Track gradients. f) Train speed profile. Page 17 of 27

18 g) Braking and accelerating capabilities of the train. h) The likelihood of a third rail traction unit becoming gapped during the movement. G A G A The rationale for assessing the driveability of the calling-on route is to identify the physical features, including gradients and the complexity of the route from the protecting signal to the stopping point, which could impact on the performance of the driver of the second train. Increasing the distance between the signal and stopping point (see A.2.3a)) increases: a) The duration of time that the move takes and the opportunity for errors of all types by the driver of the second train. b) The duration of time that there is reliance on the driver to maintain awareness that this is a permissive move. This awareness relates to short-term memory and will decay over time, meaning that the likelihood of losing awareness increases with the distance between the protecting signal and the stopping point. c) The duration of time that stopping cues are not visible to the driver of the second train. This increases the likelihood that the driver will lose awareness that this is a permissive move. G A G A G A G A G A G A.2.4 On the approach to a station with a complex switching area or throat (see A.2.3b) and A.2.3c)), several alternative routes to a given platform may be provided to enable parallel movements to be made. Each route should be assessed since their characteristics may vary significantly. A curved approach to the platform (see A.2.3d)) may obscure the position of the first train, resulting in reduced sighting time. The approach to a large station may be through a tunnel, over complex pointwork, and with changes of gradient and curves. Issues may arise due to the train speed profile from the protecting signal to the final stopping point being affected (see A.2.2e)) by a change in gradient, for example, a hump or a dip, with the possibility that parts of the train may be simultaneously on different gradients. The train speed profile (see A.2.3f)) impacts on driveability, as higher speeds lead to less time for the driver to process the route, whereas lower speeds increase the duration of the move and therefore the opportunity for error. Changes in permissible speed also add additional tasks for the driver and lead to potentially conflicting requirements, for example an increase in permissible speed is in conflict with the movement authority to slow down to a stop. The controllability of the train when accelerating and braking (see A.2.3g)) impacts on driveability by affecting the driver s ability to change and maintain the required speed profile. Visual factors throughout the movement of the second train A.2.4 Visual factors throughout the movement of the second train: a) Poor visibility due to weather. b) Issues associated with daytime and night-time. c) Sudden changes in illumination levels, including sunlight. d) Ambient illumination. e) Clutter / complexity of the visual field. Page 18 of 27

19 f) Visual distractions from activities at locations outside the cab. g) Distinctiveness of location. h) Cab design elements limiting the field of view. G A G A This section covers visual features on the route, including sunlight and tunnels, from the permissive signal to the stopping point, which could impact on the performance of the driver of the second train. These factors can increase or decrease visibility and readability of the stopping cues; hence, they increase or decrease the likelihood of error. It is particularly important to consider these factors in relation to the readability of stopping cues (see A.2.5)). The rationale for assessing the visibility of the end of the first train is that it represents the end of movement authority for the second train and might change due to a variety of atmospheric conditions, including, but not restricted to: a) Changes in lighting levels between day and night. b) Natural lighting. c) Night-time illumination. d) Sun dazzle. e) Shadow. f) Dirt on the windscreen. g) Rain, fog or falling snow. Visibility of the end of the first train (see A.2.4a) to d)) may be affected by any combination of the above atmospheric conditions. G A Visual distractions (see A.2.4e) and A.2.4f)) might include: a) Lineside signage. b) The presence of staff on or about the line. c) Train movements on other lines. d) Staff, passengers or other activities on the platform. e) Looking out for handsignals. f) The presence of station furniture, bridges or platform awnings. G A G A G A The presence of the first train near to the commencement of the platform, together with limited visibility, reduces the opportunity for the driver of the second train to correct errors. Drivers rely on visual features to maintain awareness of where they are on the route. A featureless route with no distinctive landmarks increases the probability of drivers misinterpreting their position due to a lack of prompts (see A.2.4g)); it may also lead to reduced attention. Lack of awareness may also apply to a route with a large number of features that does not provide unique prompts. The detailed design of the driving cab (see A.2.4h)), including the position and angle of the windscreen and other windows, may result in blind spots when negotiating curves on the approach to, or along, the platform. Page 19 of 27

20 G A.2.5 Readability of stopping cues for the driver of the second train A.2.5 Readability of stopping cues for the driver of the second train: a) Visual profile of the nearest end of the first train. b) Visual factors in design of the station / platform. c) Sighting time of the end of the first train. d) Variation in position of the end of the first train. e) Other stopping cues along the route. G A G A G A G A The rationale for assessing stopping cues is to ensure that a driver has sufficient information to enable a controlled approach to the platform and a clearly defined stopping point. The cues provide an opportunity for the driver to recover from any error that may have occurred on the approach to the platform. Stopping cues may include the station or platform and other features of the route that drivers may decide to use. The position of the rear of the first train (see A.2.5a)) may be identified by twin, inbuilt tail lamps or a single, flashing tail lamp. Alternatively, a tail lamp may have been placed on the platform adjacent to the end of the rear vehicle. Recognition of the stopping point may be affected by the colour and lighting on the end of the first train, as well as the platform lighting, and may vary widely according to ambient light conditions. If the platform or its approach is curved (see A.2.5b)), the end of the first train may be hidden by either: a) Fixed infrastructure, for example, an overbridge. And b) A train or trains on adjacent lines, either stationary or moving. G A The rationale for assessing the effects of sighting times, taking into account variable visibility of the end of the first train (see A.2.5c)) is that its end may be affected by its position in the platform. For example, part of the platform may be under a canopy or round a curve, or vehicles in an adjacent platform may obscure the end of the first train. Its visibility might change due to a variety of atmospheric conditions, including, but not restricted to: a) Light levels. b) Sun dazzle. c) Shadow. d) Dirt on the windscreen. e) Rain, fog, falling snow or any combination of these. G A G A The end of the first train should provide the driver of the second train with a clearly defined and stationary stopping point. The rationale for assessing the variability in the position of the rear of the first train (see A.2.5d)) is that, if the first train is able to stop at several specified positions or vary in formation, the driver of the second train is more likely to make an error in stopping the train, for example due to an incorrect assumption or misjudgement based on previous experiences. Page 20 of 27

21 G A G A.2.6 It may be possible to provide stopping markers for use by trains that are sharing the platform. However, this could be counterproductive if it deflects attention from the position of the rear of the first train (see A.2.5e)). Factors affecting braking on the approach to the stopping point for the second train A.2.6 Factors affecting braking on the approach to the stopping point for the second train: a) Rail contamination, including, but not limited to, leaf fall, water, diesel and the effects of ice and snow. b) Gradients when stopping. c) Train braking characteristics. G A G A G A G A.2.7 The rationale for assessing the possibility of misjudgement in braking performance is to identify factors for consideration in the risk assessment that might mislead a driver into braking too late or too early; the latter would require subsequent application of power when close to the rear of the first train. The assessment should encompass features such as gradients or potential rail contamination in the portion of route where the driver of the second train will be braking to a stand. The rails may be greasy on the approach to the stopping place for the second train (see A.2.6a)) resulting in poor adhesion; this may particularly apply to locations where diesel trains regularly stand for long periods. A challenging approach to an occupied platform is where a rising gradient extends from the protecting signal, requiring a driver to apply power, and then changes to a falling gradient in or on the immediate approach to the platform (see A.2.6b)). Another situation is where a falling gradient changes to a rising gradient, which causes a driver to approach too quickly relying on the rising gradient to reduce the train s speed, only to find the first train is nearer the commencement of platform than usual. A change in the formation of the second train, for example between a multiple unit and locomotive-hauled coaches, may affect its braking characteristics (see A.2.6c)). Driver factors throughout the movement of the second train A.2.7 Driver factors throughout the movement of the second train: a) Frequency of permissive and non-permissive moves as experienced by the driver of the second train. b) Variability in experience of permissive moves at the location. c) Additional tasks for the second driver. d) Variations in the permissive and non-permissive signalling layouts for stations along the route(s). G A G A The rationale for assessing the overall characteristics of the permissive route from the protecting signal to the stopping point in the platform is to identify any factors that may influence a driver s behaviour which are not identified elsewhere. The frequency and variability of permissive movements that a driver may encounter should be considered, as one driver may make permissive movements at the same station on a regular basis, while another may receive a calling-on aspect only very rarely (see A.2.7a)). Page 21 of 27

22 G A G A The rationale for assessing the variability of permissive moves (see A.2.7b)) is that at some stations permissive working may be required on a frequent basis with drivers familiar with this type of operation, while at other stations it may be needed only occasionally or to minimise delays during degraded working conditions. In these circumstances drivers may need reinforcement of training to ensure that they remain familiar with the permissive working arrangements. The likelihood of a driver being distracted by demands from tasks additional to driving or having to perform tasks not associated with the permissive route being traversed should be assessed (see A.2.7c)). Examples include the incidence of: a) Radio channel change signs. b) Speed indicators applicable to through trains (of a higher speed than that allowed during the permissive movement). c) Neutral sections or conductor rail gaps that impact on the driving technique. d) In-cab equipment fault alarms. e) Radio or on-train telephone calls. G A G A.2.8 Optimally, drivers should encounter permissive working situations that are as consistent as possible along a route. Variations in the profile of the protecting signal (see A.2.7d)) might arise due to differing standards applicable at the times that areas along a route were resignalled. Signaller error A.2.8 Signaller error: a) Errors arising where the requirements of 3.2 are met by the use of instructions, rather than by the signalling system. b) Not identifying inappropriate automatic route setting (ARS) protocols. c) Confusion on the space available in a platform. G A G A G A G A The rationale is that signalling controls not included in the interlocking should be replicated by signallers actions that are set out in GE/RT8000 Rule Book or local instructions. Pre-2000 installations and mechanical interlockings may not contain all the controls set out in GK/RT0044. Particularly likely to be missing is the holding of the platform starting signal at red until the second train has come to a stand. In such circumstances, the local signalling instructions should require that the platform starting signal is held at danger until the second train has stopped (see A.2.8a)). The rationale for assessing the risk associated with allowing ARS to set permissive routes is to avoid trains being admitted to the wrong platform or in the wrong sequence. Although it is possible for ARS to be programmed to enable regular, timetabled permissive working, care should be taken to ensure that the process is robust and reliable, as the consequences to service performance while errors in routing are corrected are likely to be severe. Secondary hazards can also arise due to errors, as is the case when passengers irregularly detrain when not all of a train can be accommodated at a platform. In order to minimise the potential for ARS introducing an error in routing (see A.2.8b)), the method used to input and transmit train description information should be robust, with concise data that is not open to misinterpretation. Page 22 of 27

23 G A Other errors by signallers may include: a) Admitting a wrong train into an occupied platform. b) Failing to caution the second train at the protecting signal, where this is by instruction. c) Incompatibility between the installed calling-on routes and the instructions to signallers on how they are to be used. G A G A G A.3 G A.3.1 Confusion on the space available in a platform (see A.2.8c)) could result in the second train being too long for the platform capacity. It may be appropriate to divide the platform train detection equipment into sections to enable the signaller to better judge the space available. Where axle counters are provided to give an estimate of the number of vehicles in a platform, based on the number of axles detected, the signaller should be advised of any train formations that might result in misleading indications. This could occur when four wheeled or articulated vehicles are included in train consists. Factors affecting the consequences from a collision A.3 Factors affecting the consequences from a collision The rationale for assessing the risks associated with the consequences of a collision is to enable mitigating measures to be put in place, if necessary. These may include: a) Restriction of permissive working to specific circumstances, for example daylight, clear weather or during perturbed working only. And b) Provision of train detection or instruction to signallers to permit permissive working to be limited to a portion of the platform. A.3.1 The speed that the second train is likely to reach during the permissive move which will influence the severity of a collision. G A.3.2 The speed that a potentially colliding train is likely to attain may be conditioned by the distance and gradient(s) between the protecting signal and the rear of the first train. A.3.2 Passenger loadings of the first and second train. A.3.3 A.3.4 A.3.5 The likelihood of passengers standing, waiting to alight. Passengers attempting to alight from doors not adjacent to a platform when a long train has been misrouted onto a platform with insufficient space to fully accommodate it. Crashworthiness of the rolling stock. G A.3.3 Injuries may result from seat or table displacement, luggage falling from overhead racks or items projected from tables. The extent of such injuries depends on the interior design of the rolling stock of the trains concerned. G A.3.4 The likelihood of injuries to passengers as a consequence of permissive working should be balanced against the risk from slips, trips and falls where passengers have to negotiate bridges or subways as a result of trains being accommodated at different platforms. Page 23 of 27

24 A.3.6 The potential for a secondary collision on an adjacent line that may be fouled by a permissive working collision. A.3.7 A.3.8 Fire resulting from spillage of fuel, for example from diesel multiple units (DMUs). The type of train that may be involved in a secondary collision, for example a passenger train or freight train carrying hazardous goods. G A.3.5 Although it might be expected that most collisions resulting from a permissive movement will be at low speed, an adjoining line might be fouled, particularly where the platform is on a curve. A secondary collision may then occur with vehicles, moving or stationary, on an adjacent line. A.3.9 At terminal or bay platforms, standing vehicles being pushed through the buffer stops onto the station concourse. G A.3.6 The likelihood of damage or injury from standing vehicles being pushed through the buffer stops depends on the speed of the colliding train, the layout of platform furniture, including kiosks or seats, and the likely disposition of intending or alighting passengers on the station concourse. Page 24 of 27

25 Definitions and Abbreviations ARS Automatic route setting. DMU Diesel multiple unit. Driveability The extent to which the overall signalling system, within the operational and infrastructure context, is compatible with a driver s capabilities in terms of vigilance, attention, information processing and memory so that the workload is not excessive and the likelihood of a driving error is minimised. First train A train, or trains, that are already occupying the platform or line towards which the permissive move takes place. Freight train For the purposes of this document, trains signalled as classes 3 to 8 and 0. By this definition, light engines and trains comprising empty coaching stock or parcels trains, are permitted to use facilities provided for freight trains. Joining trains Coupling two or more sets of vehicles together to form a longer train. Note: splitting of trains does not require the controls set out in GK/RT0044. Occupied line A portion of a running line between two successive signals which is capable of displaying a stop aspect, or between such a signal and the end of the line, on which a train, or a part of a train, is already positioned. Passenger train For the purposes of this document, trains signalled as classes 1, 2, 3 (where specially authorised), 5, 9 or 0. By this definition, light engines and trains comprising empty coaching stock or parcels trains are permitted to use facilities provided for passenger trains. PF Permissive freight. Platform line A line that is adjacent to a platform at a through or terminal station. Platform sharing Permitting two trains (both of which are passenger trains) to occupy a platform line simultaneously, other than for the purposes of attaching, detaching or removing vehicles, without the existence of a mid-platform signal. Platform starting signal For the purposes of this document, a platform starting signal is the signal controlling the onwards movement of the first train. Point of visibility The position from which the driver of the second train has a clear and continuous view of the nearest end of the first train. PP Permissive passenger. Uncontrolled When Printed Page 25 of 27