Developing human factors/ergonomics as a design discipline

This paper deals with internal challenges that the human factors/ergonomics (HFE) research faces when wishing to strengthen its contribution to development of work systems. Three established characteristics of high-quality HFE, i.e., HFE takes a systems approach, HFE is design-driven, and HFE focuses on two closely related outcomes, performance and well-being, are taken as a starting point of a methodological discussion, in which conceptual innovations, e.g. adopting the technology-in-use perspective, are proposed to support development of HFE towards the high-quality aims. The feasibility of the proposed conceptual choices is demonstrated by introducing a naturalistic HFE analysis approach including four HFE functions. The gained experience of the use of this approach in a number of complex work domains allows the conclusion that becoming design-driven appears as that most difficult quality target for HFE to reach. Creating an own design discipline identity in a multi-voiced collaboration is the key internal challenge for human factors/ergonomics.     

Methodological considerations in analysing anaesthetists' habits of action in clinical situations

Human activity can be seen as an intentional, context-dependent enterprise explained through meanings the actors attach to their activity and their directly observable interactions with the environment. The authors have demonstrated previously a new conceptual framework to describe the anaesthetist's activity. One of the central concepts besides orientation is habit of action referring to the way in which the actor has organized his actions when interacting with his environment, in this case a patient with unique physiological potentials, information monitors and anaesthetic drugs. The activity dependent on contingent, particular circumstances, needs to be studied as it appears in a natural situation. Using an idiographic study design the authors have examined the activity of eight expert anaesthetists in clinical settings to determine the characteristics of their habits of action. To capture the fleeting circumstances during the anaesthetic process, a wide observational basis was necessary. It consisted of videotapes, detailed expert observations, and interviews. The conceptual analysis of the subject, habit of action, is described step-by-step. Two distinct habits of action could be identified, confirming earlier results. The interpretative habit of action was characterized by extensive use of situational information in order to construct a cumulative conception of the patient's physiological potentials to control the process accurately. Moreover, rich dialogue between formal professional knowledge and patient-specific, particular knowledge was evident. The reactive habit of action was characterized by a tendency to regulate the process by means of predetermined conventional ranges of measured patient parameters shown by monitors. The authors discuss their methodological solutions and results, and explicate their differences to the earlier approaches.     

On the use of fractional Brownian motion in the theory ofconnectionless networks

An abstract model for aggregated connectionless traffic, based on the fractional Brownian motion, is presented. Insight into the parameters is obtained by relating the model to an equivalent burst model. Results on a corresponding storage process are presented. The buffer occupancy distribution is approximated by a Weibull distribution. The model is compared with publicly available samples of real Ethernet traffic. The degree of the short-term predictability of the traffic model is studied through an exact formula for the conditional variance of a future value given the past. The applicability and interpretation of the self-similar model are discussed extensively, and the notion of ideal free traffic is introduced     

Core task analysis in accident investigation: analysis of maritime accidents in piloting situations

This article discusses the difficulties in utilising accident analysis as the basis for the development of complex socio-technical systems, and how to improve accident analysis to better meet such aims. It focuses on two themes: accident models and experts’ involvement in accident investigation. The article describes the development of a new core task analysis-based method for accident analysis. It also elaborates on the method by presenting summarising results of an investigation in which several maritime accidents were first analysed case-by-case, followed by a comparative analysis and a synthesis. The latter phases aimed at providing evident-based generic explanations for the accidents. The accidents occurred in Finnish coastal waters during sea or canal piloting between 1997 and 2000. The authors participated in both phases of the investigation for which the Finnish Accident Investigation Board was responsible. The presented method is argued to promote solutions to two current problems in accident investigation: generalisation from the results, and integration of the experts’ work.

Evaluating the potential of new technological tools for safety critical work

Defining user requirements of complex human–system interaction technologies and testing the fulfilment of these requirements in the end-product are issues of design practice that are currently not solved in an optimal way. In the current paper several dilemmas of “task-artefact-cycle”, “abstraction level of requirements” and the “tendency for conservative decisions” in requirement definition and testing are tackled. A new simulation method is proposed to tackle these design dilemmas in a case study on emergency response (ER) activity. Modelling and simulation are used as means to anticipate future activity, and the concept of “zone of proximal development” serves to illustrate the change in work demands of the ER activity. One of the key issues in ER is to create a realistic and timely understanding of the situation and to identify adequately the needs for action, the Common Operational Picture (COP). In the project, prototypes of new technological tools were designed to facilitate creation of an appropriate COP. First, normal emergency response activity was modelled. Then, the modelled situation and corresponding activity were enacted by competent actors as undisturbed as possible. Parallel to this, a second activity took place. This involved two professional fire fighters acting in the roles of incident commander and supporting officer. They observed the actual demands of the situation and the activities of the first responder actors. They also observed the available information provided by the new technologies. In the present paper the focus is on the presentation of the design and evaluation methodology. The demonstration of the methodology in a complex design task indicates the feasibility of the approach.     

The superposition of variable bit rate sources in an ATMmultiplexer

When variable-bit-rate sources are multiplexed in an asynchronous transfer mode (ATM) network, there arise queues with a particular form of correlated arrival process. Such queues are analyzed by exploiting a result expressing the distribution of work in system of the G/G/1 queue originally derived by V.E. Benes (1963). A simple alternative demonstration of this result is analyzed and extended to the case of fluid input systems. The result is applied first to a queue where the arrival process is a superposition of periodic sources (the Σ D_i/D/1 queue), and then to a variable-input-rate constant-output-rate fluid system. The latter is shown to model the so-called burst component of the considered superposition queuing process. The difference between this and the real queue, the cell component, can be evaluated by means of the results obtained for the Σ D_i/D/1 queue. The relative importance of these two components is explored with reference to the particular case of a superposition of on/off sources     

Architectural issues of ATM based connectionless overlay network

Connectionless service such as SMDS, or its European equivalent CBDS, can be provided by an ATM network by building a separate connectionless overlay network (CLON) on top of the ATM bearer service. A CLON is composed of a number of connectionless servers, CLSs, which provide the routing function, connected by semipermanent virtual paths (VPs). In this paper, architectural issues related to the design of a CLON are studied. In particular, we address the question of the optimal number of CLSs and their interconnection topology, assuming the underlying ATM network and the mean connectionless traffic load are known. The objective of the design process is to meet given design criteria with minimum costs. The QoS requirements of the SMDS/CBDS service are briefly reviewed and a simple cost model for the CLON network is given. The dimensioning of the logical links is also considered. Then the design process to find the optimal solution for the whole network is outlined. A simplified procedure was applied in numerical studies of the topological optimization. In order to find the general dependence of the optimal number of CLSs on the size of the network and other network parameters, the optimization procedure was applied to a large number of sample ATM networks, generated by an algorithm which is briefly described. Results from these studies are presented and discussed.     

Design of joint systems: a theoretical challenge for cognitive systems engineering

In this paper the “joint systems approach” will be discussed. The approach is considered as a new paradigm in cognitive systems engineering (CSE). Its central idea, that human and technology form a functional unity, is as such not new. Why, then, has this idea become so appealing right now? In the first part of the paper we seek answers to this question by analysing the current situation in product design. The conclusion is that the focus of design is shifting from single products to intelligent environments. This change in focus induces tensions into the design process that urge for solutions. One of them is re-conceptualising the relationship between human and technology, precisely what the joint system approach is about. Three different joint system approaches are considered: the joint cognitive systems approach (JCS), the Risö extended CSE approach, and the joint intelligent systems (JIS) approach proposed by us. Comparisons are made with regard to how these approaches understand the joint system to be organised. While the JCS approach focuses on the human–technology relationship, the other two consider this relationship as embedded in a context of object-oriented activity. As a consequence, environment becomes included in the joint system. In JIS approach we propose the use of the semiotic concept of habit to characterise the ways of functioning of the joint system. “Habit” is a tool for identifying generic patterns in the situation-specific behaviour of the system. Defining habits enables expressing the meaning or purpose of the system’s functioning. In the end of the paper, we propose a design process model for the development of JIS. This approach is aimed at designing systems in usage i.e. to design of practices.     

Operators’ orientations to procedure guidance in NPP process control

Resilience in nuclear power plant (NPP) process control depends, among other things, on balance between operators’ autonomy in online decisions and pre-defined guidance for operations. Striking balance between these inherent demands of process control belongs to the strategic decisions by the management, but finally balancing takes place at the sharp end, by the operating personnel. We studied operators’ basic assumptions about the role of operating procedures in action. Conceptions of 62 control room operators at two Finnish NPPs were queried. Answers were classified into theory-based categories, i.e., interpretative, confirmative or reactive orientations. Orientation is an epistemic attitude to work that influences the process and content of sense making in situations that require action. In both NPPs, the confirmative orientation, emphasising the importance of acting according to rules, prevails, which corresponds to the expectations set by the organisations. It was also found that orientations reflect the operator roles and their demands: Among turbine operators, the interpretative orientation is significantly more prevalent than among the reactor operators as regards control of action. All operators consider interpretative orientation as a characteristic of a “good operator”. It is concluded that interpretative orientation represents an epistemic attitude to NPP operator work, in which autonomy based on operators’ professional competence and procedure usage is not seen opposite to each other, but intertwined into a practice. Identification interpretativeness as an epistemic attitude relevant in action extends the notion of “intelligent use of procedures” proposed earlier, by elaborating the inherent logic and ethos of operators’ procedure usage. It is recommended that appropriation of interpretative orientation should be actively supported as a means to facilitate resilience in NPP activity.     

Hidden roles of the train driver: A challenge for metro automation

In the year 2014, the Helsinki Metro is planned to be fully automated. This automation means that the metro trains will be computer-driven and monitored remotely from a stationary control room. To investigate the challenges related to this scenario, we decided to study the ways in which the current train drivers contribute to the metro system. We conducted three separate but interrelated studies, which were based on the Core-Task Analysis method. Our results suggest that there is much more to driving the metro train than meets the eye. The drivers do not only operate the train on track and its doors at stations, but they also contribute to a variety of other important, albeit more hidden, functions in the metro system. For example, the drivers anticipate, observe, interpret, and react to events in the surrounding environment. Furthermore, they are a significant interaction link between different actors of the metro system. Our conclusion is that if the identified critical roles of the drivers are not accounted for, a migration to a fully automated metro system can affect the quality of service and raise safety issues. In addition to automated metros, the results of this research can be applicable to automation implementations also in other domains.