Theresa Clarke

Fundamental examination of mental workload in the rail industry

In recent years there has been a resurgence of interest in rail human factors. The sometimes conflicting requirements of safety, reliable performance, quality of operations and effective use of limited capacity have meant that managers and engineers across all companies in the rail network have realized the importance of understanding and designing for human factors in train driving, signalling and control, maintenance, planning, etc. One key concern has been with workload, particularly mental workload, and especially in signalling and driving. This paper is concerned with a fundamental examination of what workload means in relation to the railways and especially signalling work and with a need to develop an appropriate suite of tools for the practical assessment of workload. In order to do this, the basic literature has been revisited in order to propose a conceptual framework of mental workload in the rail industry. Subsequently, a suite of workload tools has been proposed and is being used in practice; this is also described in this paper.

On the Right Track: Systematic Implementation of Ergonomics in Railway Network Control

Abstract: At a time of change for the railway networks of Europe we have been developing tools to assess ergonomics aspects of railway network control. This is within the Railway Ergonomics Control Assessment Package (RECAP). Among the developments have been an audit instrument (REQUEST), tools to assess situation awareness (RESA) and staff loading (RELOAD), and workshops to predict opportunities for human error and organisational failure across rail network operations. This research is discussed with respect to the context of UK railway operations and the need for an expanding tradition of cognitive ergonomics fieldwork. From the findings we draw some conclusions about the roles filled by signallers, electrical controllers and zone controllers within a perspective of distributed cognitive/social networks.

Practical use of work analysis to support rail electrical control rooms: A case of alarm handling

Renewals and especially enhancements of rail signalling and control systems are increasingly including a strong programme of human factors integration. One contribution to the human factors work that is required is work analysis – the understanding of what tasks and functions exist in current work systems, the artefacts (controls and displays used) and the strategies employed by skilled operators. One increasingly common approach to such work systems analysis is cognitive work analysis (CWA), used to develop understanding of a work domain and tasks in a structured fashion and as a basis for new design recommendations. The purpose of this paper is to explain, for an engineering and systems developer audience, the basis for and use of CWA. This is done in the context of rail electrical control rooms and especially the use made of various information display elements including alarms.

Developing a Rail Ergonomics Questionnaire (REQUEST)

In this first of two papers the development of a shortened version of the Rail Ergonomics Questionnaire (REQUEST) is described. REQUEST has been designed to survey attitudes and opinions of railway workers on a range of human factors issues, with scales based on those used and validated elsewhere or else specially developed on the basis of studies of rail workers. Important characteristics of different roles, especially signallers, are outlined. The longer version of the questionnaire has already been used on a number of occasions for samples of 100-150. The shortened version was developed for the most recent administration of the survey to a large population. An expert group reviewed question wording, and the findings from the principal components analysis and other analyses of data from previous administrations of the survey. Improvements were made to the design and layout of the questionnaire. The effectiveness of the process for the expert review of questions is discussed. The survey was administered to high proportions of the target groups during the company safety briefing programme and achieved a sample size of almost 4000 respondents at an overall response rate of 83%. Findings from the REQUEST national survey are presented in a companion paper [Ryan, B., Wilson, J.R., Sharples, S., Clarke, T., 2008. Attitudes and opinions of railway signallers and related staff, using the Rail Ergonomics Questionnaire (REQUEST). Appl. Ergon., in press. doi:10.1016/j.apergo.2008.04.010].

Visual scenario analysis: understanding human factors of planning in rail engineering

A recent requirement to increase train capacity of the UK rail system has resulted in a significant rise in the amount of rail engineering work. The need for staff and machines to access the track in a safe and more efficient way has thrown out a number of challenges to the industry, not least in terms of the planning and scheduling of larger amounts of work. Human factors related research has been carried out to understand the human and organisational factors that affect performance in the planning of work. We describe the development and application of a visual scenario based approach which has been used to understand both engineering work planning generally, and to identify the human and organisational factors which influence plans. We report on the specific development of a tool which has been used within workshops to identify potential risks of a proposed new system for protecting workers and discuss its potential as a decision support tool to be integrated into the planning process.

Investigating presentation of rail-specific spatial information on handheld computer screens

Spatial information is one of the most commonly used items of information for rail maintenance workers and providing this information to track workers while mobile offers potential advantages in terms of efficiency and communication accuracy. However, displaying track diagrams and other rail-specific spatial information on the small screen of a handheld computer presents several human computer interaction challenges that need to be considered. Three experiments were conducted to investigate different aspects of presenting spatial information on handheld computers. These experiments were conducted with current job holders at their place of work. The first experiment aimed at investigating the differences between presenting rail-specific information on handheld computers compared with paper-based documents. Using a combination of qualitative and quantitative methods, the findings of this experiment demonstrate the potential for handheld computers to provide a more efficient and effective means of displaying rail spatial information. The second experiment aimed to discover the optimum amount of information that can be presented on the screen of a handheld computer device. The results of this experiment demonstrate that although different combinations of length of track and amount of information affect user’s performance, the structure of spatial information displayed on the screen is also very important. The third experiment identified that although the type of information presented to the track workers did not have an effect on their performance, postexperiment interviews revealed the importance of the type of information for track workers depending on the type of task they perform. These findings have implications for the design of small screen representations of spatial information in future mobile devices.

A framework of data processing for decision making in railway intelligent infrastructure

Intelligent infrastructure is an architecture that enables generation of immediate, accurate and relevant information about the state of any type of infrastructural asset and converts this information to timely and reliable decision aids. The study presented in this paper identifies the scope of railway intelligent infrastructure system via a mixed contextual and sequential approach. The output from this study is a framework that identifies and explores the data processes required for decision making within a railway intelligent infrastructure system. Findings will assist designers to present the correct level of detail for various stages identified for intelligent infrastructure

Management of Personal Safety Risk for Lever Operation in Mechanical Railway Signal Boxes

Despite increased implementation of computer control systems in managing and regulating rail networks, mechanical signal boxes using lever operation will be in place for years to come. A rolling risk assessment programme identified a number of levers in mechanical signal boxes within the UK rail network which potentially presented unacceptable personal safety risk to signallers. These levers operate both points and signals and the risk is primarily the weights which have to be moved when pulling and pushing the levers. Operating difficulties are often compounded by the design and condition of lever frames, the linkages to the points/signals, maintenance regimes, the workspace and the postures and strategies adopted by signallers. Lever weights were measured as from 15 kg to 180 kg at over 160 boxes, using a specially designed and constructed device. Taken together with examination of injury and sickness absence data, interviews and field observations, and biomechanical computer modelling, the measurement programme confirmed the potential risks. A risk management programme has been implemented, comprising lever weight measurement, training of operations staff, a structured maintenance regime and renewal or redesign for boxes/levers where, after maintenance, a criterion weight level is still exceeded. For a feasible management programme, the first alert (or 1st action) value for further assessment is 55 kg, a second action level requiring specified maintenance is 80-99 kg, and a third action level requiring the lever to be signed out of use is 100 kg.