Assessment, re-design and evaluation of changes to the driver's cab in a suburban electric train.

A new type of electric train, called the Tangara, began replacing older trains on the Sydney city and suburban network in 1990. Shortly afterwards, some of the train drivers began reporting pain in the arms while driving the new train. The Ergonomics Unit of Worksafe Australia was then engaged to identify and assess ergonomic problems in the driver's cab. This process included direct observation of drivers at work, distribution of a self-administered questionnaire to all drivers, and analysis of anthropometric problems using a computer-aided design package. The analysis of 193 completed questionnaires and the problems shown by the design study were used in developing an improved design. A mock-up of the modified cab was made and tried out by 134 drivers whose comments led to further changes. The modified design was applied to new production, and existing cabs were modified during major maintenance. By 1996, 96% of the driver's cabs were to the new design. An evaluation of the new design was undertaken using written questionnaires, which were completed by 227 drivers. The results were strongly in favour of the new design, showing the effectiveness of the ergonomic modifications.

A comparison of risk assessment of single and combination manual handling tasks: 2. Discomfort, rating of perceived exertion and heart rate measures.

Although many manual handling activities involve combinations of pull, lift, carry, lower and push, there are few reports of investigation of how to assess the risk in these combination tasks. Two strategies have been suggested in the literature for estimating the risk in a combination task based on the measures of the separate components of that task. The aim of the study was to compare the risks assessed in single manual handling tasks with those in combination tasks. Ratings of discomfort, exertion and heart rate were collected from nine male and nine female students, performing combination and single tasks. Combination tasks consisted of sequences of pull, lift, carry, lower and push tasks. Combination tasks were performed at 1.min-1 and 3.min-1 whilst single tasks (lift, lower, push, pull and carry) were performed at 3.min-1 and 6.min-1. The rating of exertion and heart rate for each combination task was compared to the exertion rating and heart rate of the single tasks which comprised the combination task using repeated measures analysis of variance with specified contrasts. Similar comparisons for the discomfort data were performed using Friedman and Wilcoxon tests. In at least one of the twelve comparisons performed for each dependent variable, the combination task value was significantly different to each single task value. The differences occurred regardless of whether the most critical single task value or an average of all single task values was used. It was concluded that the risk in combination manual tasks can not be accurately assessed by using estimates from discomfort, exertion ratings and heart rate measures of single tasks.

A comparison of risk assessment of single and combination manual handling tasks: 1. maximum acceptable weight measures.

Many manual handling activities involve combinations of pull, lift, carry, lower and push, yet few studies have investigated how to assess the risk of such combination tasks. Most recommendations assume that a combination task can be split into its components for assessment. The aim of this study was to compare the risks assessed in single manual handling tasks with those in combination tasks. Nine male and nine female students participated in a study to determine Maximum Acceptable Weights (MAWs) in single and combination tasks at different frequencies (1 min-1 and 3 min-1 for combination tasks and 3 min-1 and 6 min-1 for single tasks) and heights (floor, knuckle, shoulder). Combination tasks consisted of one each of the single tasks (pull, lift, carry, lower and push). The MAW of each combination task was compared to the MAWs of the single tasks of which it was composed using repeated measures analysis of variance with specified contrasts. In at least one of the 12 comparisons each single task MAW was found to be different from its related combination task MAW. It was concluded that the current use of single task MAWs to estimate the risk in combination tasks was unacceptable. Prediction models for combination task MAWs based on single tasks MAWs were also developed, using step-wise regression. Although coefficients of determination of around 0.8 were achieved it was argued that owing to their situation-specific nature the prediction of combination task risk using single task MAWs was likely to result in unacceptable risk errors.