Reducing The Risk of Signallers Giving Level Crossing Users Permission To Cross When It Is Not Safe To Do So

Chris Hack

Network Rail

Chris HackI am a railway signalling operations specialist supporting the Network Rail Ergonomics team. I have 20 years rail industry experience including a five year period in ‘hands on’ roles managing frontline signalling and operations staff operating a broad range of signalling equipment including mechanical lever frames, route setting panels and VDU based signalling control systems across three different business units. I have also been involved in operations training development, learnt signalling design principles to an advanced level, carried out train performance analysis, competence management, incident investigation, signalling project development, health and safety management and signalling overrun risk assessment. Before joining the Ergonomics team in April 2012 I spent six years in the FTN/GSM-R Programme developing and testing user training and procedures, carrying out in service reviews and preparing GSM-R call routing requirements. Key Areas of workMy job is to provide signalling and operations expertise to support the team in the following areas: Task and error analysisTask analysis is a key part of my role. Every piece of work starts with a task analysis to make sure I have considered the full range of tasks relevant to the analysis being undertaken. Examples include: Tasks carried out by frontline staff involved in incidents and associated error mechanisms. Tasks carried out by signalling staff where workload concerns have been identified. Proposed tasks to be carried out by users of new or modified systems. Changes in tasks carried out by signalling staff following changes in operational procedures. Changes in tasks carried out by signalling staff where infrastructure projects are proposed. Design advice and requirementsIdentifying steps in expected equipment behaviour in response to end user inputs (and vice-versa) is a key step in giving design advice on solutions to human factors issues, such as: Design solutions to reduce likelihood and impact of human error. Changes to existing signal boxes and signalling centres to reduce signaller workload. Design advice to address human factors issues affecting users of new or modified systems. Design advice to enable the implementation of procedural changes. Specifying requirements (and accompanying rationale) for the design of infrastructure projects. Usability testing and reviewTesting proposed system developments and procedural changes against usability and operational requirements and carrying out in service reviews as appropriate, for example: Assessing the effectiveness of design solutions in reducing likelihood of error. Carrying out in service reviews to monitor the validity of workload assessments. Verifying end user needs have been met through new or modified systems. Testing and monitoring the effect of procedural changes. Assessing the effectiveness of specified requirements in meeting end user meets.

Abstract

Network Rail has 1720 level crossings where the safety of crossing users is dependent on the user contacting the signaller and the signaller advising whether there is sufficient time to use the crossing before the next train... [ view full abstract ]

This type of crossing is normally protected by gates on both sides of the railway. The gates, normally closed across the road and hung so as to open away from the railway, are operated by the user, hence User Worked Crossing (UWC). A UWC may be used by vehicles, animals and pedestrians.

Users should have sufficient time from first seeing an approaching train to cross safely. However, where the available sighting distance is inadequate and sufficient warning time cannot be obtained, telephones to the signaller may be provided, known as a UWC (T) crossing.

However, where the signaller does not have reliable information concerning the whereabouts of trains, or the information available would be so restrictive that it would be likely to cause the user to become unduly impatient and to cross without permission, the signaller is required to make estimates of train position. This includes whether any train in section has passed over the crossing yet and whether any approaching train will reach the crossing before the user has passed clear.

The key challenge is to develop a generic approach to risk control at a UWC (T) crossing which includes:

Assessment of the relative importance of factors contributing to the risk of signallers giving permission to cross when not safe to do so;
Assessment of the effectiveness of reasonably practicable risk reduction measures to control that risk.

Assessment of the risk of signaller error involves evaluating the effect of various Performance Shaping Factors on the likelihood of signaller error, by establishing:

The generic operational scenarios the signaller is expected to manage;
The fixed system/location specific scenario variants, for example, if:
- The track section is too long for the signaller to be able to tell the user to call again when the next train passes or after a period of time by which time the signaller will be able to confirm that the train has passed clear of the track section;
The dynamic scenario variants, for example, if:
- There is a train in section when the call is received from the crossing;
The performance criteria the signaller is expected to meet when responding to the scenario;
The signaller’s generic goals in each scenario;
The signaller’s generic sub-goals to achieve each goal;
The tasks the signaller needs to carry out to achieve each sub-goal;
The level of demand and complexity associated with each task;
The potential errors which could be made in each task;
The performance shaping factors which could influence each error.

Implementation of reasonably practicable risk reduction measures involves developing control measures and evaluating their effectiveness in terms of:

Eliminating signaller tasks and thereby associated demand and error;
Making tasks less demanding;
Reducing the likelihood of error;
Safety cost-benefit analysis for each risk reduction measure identified.

Authors

Chris Hack (Network Rail)
Mike Carey (Network Rail)

Topic Areas

Ergonomics design in control facilities, train cabs and rolling stock , Signaller performance, workload, situation awareness , Systems safety, risk management and incident reporting , Human error and human reliability , Level crossings safety, design and operation

Session

Si-1 » Signaller (14:00 - Wednesday, 8th November, Illuminate)

Paper

Reducing_the_Risk_of_Signallers_Giving_Level_Crossing_Users_Permission_To_Cross_When_It_Is_Not_Safe_To_Do_So_v1.0_FINAL.pdf

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