The ergonomics of video display terminal workplaces in international telephone exchanges

Since 1976 the author has worked with L. M. Ericsson Ab of Stockholm, Sweden, providing ergonomics advice relating to the design of operator positions for stored program controlled telephone exchanges manufactured by this company. The research was I performed in three phases: a literature review, preliminary experiments to evaluate alternative equipment designs and finally a series of trials of the prototype under simulated call conditions. The basis of the new operator position is tie provision of a computer terminal, consisting of a datascreen or video display unit (vdu) and keyboard at each operator desk. These terminals enable the operator to enter call details into memory stores from which they can be 'read' by the computer, displayed at any operator position or routed to the charging system. By eliminating many repetitious and error prone number entries, by abolishing pager handling tasks completely and by automating certain call handling operations a more efficient and effective service can be provided to subscribers. The literature review report, produced on completion of Phase I, summarised the ergonomics research relating to datascreens, keyboards, dialogues, workstations and environmental factors. As a result of the review the author was able to produce detailed ergonomics recommendations for many parts of the system. Phase II consisted of a programme of experiments to provide the data required to resolve design conflicts remaining at the conclusion of Phase I. In successive stages a panel of experts reduced the potential number of datascreen designs to practicable numbers for controlled experiments. These datascreens, filters and screen treatments were systematically compared in experiments and a suitable design was selected. In Phase III an experiment was conducted to evaluate the entire operator position under simulated call handling conditions. In addition to collecting objective measures of call handling speed and accuracy, the experiments also enabled visual fatigue to be assessed and call handling equipment and procedures to be judged by experienced operators under' reasonably realistic conditions.