Anthropometric study of Swedish engine drivers.
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Adult↗
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Estimation of maximum permissible loads to be carried by Indians of different ages.
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Adult↗
Locomotive engineers and their spouses: coffee consumption, mood, and sleep reports.
Locomotive engineers (train drivers) on irregular work schedules reported a general coffee consumption rate higher than that reported by a comparison sample of permanent shift factory workers. The present study examines the impact of this consumption on workday and non-workday sleep behaviour and mood ratings. Twenty-seven engineers and their spouses each completed daily logs for 30 consecutive days. Daily logs were then sorted into workday and non-workday categories. Workday sleep length was significantly shorter than non-workday sleep length for both engineers and spouses. For the engineers only, coffee consumption on workdays was higher than on non-workdays. This increased coffee consumption was correlated with longer sleep latency, increased negative mood, and decreased positive mood on both work and non-workdays. This was not true for spouses. These results may be related to a days-off carry-over effect of caffeine or a general consumption behaviour characteristic.
Adult↗
Human vigilance in railway and long-haul flight operation.
Human operators in transport operations are often confronted with monotony, boredom, and irregular work schedules. This situation has become increasingly more acute because of the growing automation of systems. This paper presents methodology and preliminary results for two field studies on the vigilance of train drivers and long-range aircrews. The aim of these studies was to identify factors that can modify vigilance and to elaborate several specific solutions for reactivation. The method is based on the collection of physiological data in the field and on task observation of the operators. The recorded physiological data (EEG, EOG, EKG) permit an evaluation of vigilance and mental workload. The rest-activity cycles are estimated by actometry. The use of EEG and EOG are discussed in relation to monotony and sleep deprivation. For pilots, results show a high occurrence of decreased vigilance, particularly during phases of low workload (i.e., when cruising). Furthermore, it was shown that these periods of lowered vigilance can occur at the same time for two crew members. A great number of incidents of decreased vigilance were also observed for the train drivers. These incidents occurred even though the operators sometimes had high levels of activity. A direct relation was also noted between sleep duration and the onset of rest. These studies provide several means for maintaining vigilance during activities and improving the system of work schedule rotation.
Adult↗
Analyses of cognitive processes in train traffic control.
The study of complex information processing and problem-solving situations in practice is discussed, in particular the methods of analysing the cognitive aspects in train dispatcher's work. Some parallels are drawn with related work in processing industries. A prerequisite for the approach to the issue was that the results would have to yield very concrete starting-points for the design of technical aids. The research started from the assumption that it would be extremely difficult to derive design indications from apparently observable actions of the train dispatchers. This led to the choice of a combination of a preliminary simulation study followed by analysis of cognitive processes in the train dispatcher's behaviour in every day practice. It turned out to be helpful for the analysis to draw parallels between the cognitive processes in the behaviour of the train dispatchers and the way of working/thinking shown by test subjects in complex problem-solving experiments.
Cognition↗
The prediction of recommended energy expenditure for an 8 h work-day using an air-purifying respirator.
Thirty railway workers executed maximal, or near maximal, stress tests with and without the use of a half mask air-purifying respirator (Spasciani 85 A1 P1) fitted with two combined filters for simultaneous protection from organic vapours and particulate matter. The pressure-flow characteristics of inspiratory and expiratory resistance at airflows in the range 0-90 l.min-1 were established by a continuous flow method on one test mask. Significant differences were found by paired t-test between the two exercises (with and without use of mask), showing reduced values with use of the mask, for breath frequency, ventilation rate, oxygen uptake, carbon dioxide production, maximal oxygen uptake, percentage of maximal voluntary ventilation used at the maximal exercise ventilation. No significant differences were found for tidal volume, respiratory quotient, heart rate, systolic blood pressure, oxygen uptake at anaerobic threshold, and duration of exercise. The predicted energy expenditure recommended for an 8 h work shift, corresponding to 40% of maximal oxygen uptake, is found to be reduced working with respirator and is significantly different from that observed during stress test without mask. The average ventilation rate at this workload is below 25 l.min-1, with predicted inspiratory mouth pressure equal to, or less than, 20 mm H2O. This maximal inspiratory mouth pressure is proposed as a safety limit for prolonged work using a respirator, with a recommended energy expenditure close to 40% of maximal oxygen uptake.
Adult↗
Physical, mental, emotional, and subjective workload components in train drivers.
This study, using 12 train drivers on a high speed track and 11 drivers on a mountain track, tried to differentiate between the physical, emotional, mental, and subjective workload components imposed on the drivers during work. With the simultaneous recording and on-line analysis of heart rate and physical activity, the emotional component in terms of the so-called additional heart rate was separated from the physical component. Mental workload was calculated by the heart rate variability and by shifts in the T-wave amplitude of the ECG. Speed of the train, mode of driving, and stress of the situation were rated by two observers who accompanied the drivers in the cabin. During speeds up to 100 km/h as compared to standstills no heart rate changes occurred, but with speeds from 100 km/h up to 200 km/h heart rate decreased indicating a monotony effect. However, heart rate variability, and T-wave amplitude indicated higher mental load during driving in most speed categories. Starting the train and coming to a halt showed greater emotional workload as compared to moving. Observer ratings of stress and subjective ratings of stress by the drivers revealed several discrepancies. Discrepancies were also seen between workload as indicated by the physiological parameters, and corresponding stress ratings by the observers or by the drivers.
Heart Rate↗
Cognitive task analysis: harmonizing tasks to human capacities.
This paper presents the development of a cognitive task analysis that assesses the task load of jobs and provides indicators for the redesign of jobs. General principles of human task performance were selected and, subsequently, integrated into current task modelling techniques. The resulting cognitive task analysis centres around four aspects of task load: the number of actions in a period, the ratio between knowledge- and rule-based actions, lengthy uninterrupted actions, and momentary overloading. The method consists of three stages: (1) construction of a hierarchical task model, (2) a time-line analysis and task load assessment, and (3), if necessary, adjustment of the task model. An application of the cognitive task analysis in railway traffic control showed its benefits over the 'old' task load analysis of the Netherlands Railways. It provided a provisional standard for traffic control jobs, conveyed two load risks -- momentary overloading and underloading -- and resulted in proposals to satisfy the standard and to diminish the two load risk.
Cognition↗
Treatment of oro-facial hypersensitivity following brain injury.
A 56 year old man who was 10 months post-severe traumatic brain injury was unable to tolerate oral hygiene. He had oro-facial hypersensitivity, oral dyspraxia and limited oral function. Poor oral hygiene with coating of oral structures and infection was present. An intensive systematic desensitization programme over 2 weeks, even at this late stage post-injury, increased oral tolerance and allowed full oral hygiene. Participation in oral hygiene and functional patterns of movement also improved, enabling some oral nutritional intake. This case study provides controlled evidence, very little of which exists in the literature, to demonstrate the effectiveness of these treatment techniques
Accidents↗
Train drivers' sleep quality and quantity during extended relay operations.
Relay operations are an important mode of freight transportation within Australia. Relay work requires multiple crews to drive the train continuously from one specified destination to another and return. Importantly, the nature of relay work requires train drivers to sleep on-board during designated resting shifts. The main aim of the present study was to investigate the quality and quantity of sleep obtained in on-board rest facilities (relay vans) during extended (four-day) relay operations. Drivers (n = 9) working the Port Augusta to Darwin relay operation volunteered to participate. The first leg of the trip typically took 40 h followed by an overnight stay in Darwin (between 8-12 h) prior to return. Two crews, each consisting of two drivers, changed every 8 h, giving the crew an 8 h rest in the relay van prior to each 8 h working shift. Using polysomnography, home sleep data were collected prior to and following each trip using a standard five-channel EEG montage. All sleep periods during the relay trip (including Darwin) were also recorded. Additionally, subjective sleep quality ratings were recorded following each sleep period. Analyses revealed that the quantity of sleep obtained in the relay vans (3.3 h) was significantly reduced compared to home (6.8 h). In general, the total sleep time was increased at night and reduced during the day. In terms of quality, sleep onset latency, sleep efficiency, and amount of slow wave and rapid eye movement sleep did not differ significantly between home and the relay vans. The results of the study highlight sleep quantity as the main concern during extended relay operations. Future research should focus on investigating the subjective and objective impact of this sleep reduction on waking functions.
Adult↗
An exemple of particle concentration reduction in Parisian subway stations by electrostatic precipitation.
The air quality in Parisian subway stations is a great concern to users and the public authorities. Particle concentration is one of the major problems; indeed concentrations observed in stations are generally superior to those collected in the street. The subway generates its own particles from wheels / rail contact, braking, the ground... One of the ways explored to lower this level of particles is a removal treatment: the principle is to treat the ambient air using a suitable system placed in stations. Following literature, the process chosen by Paris Transport Authority is the electrostatic precipitator. An electrostatic precipitator prototype from the Recycl'Air company is installed in May 2001 in a closed station on the 5th line (Italy Place -Bobigny). Results show that, by the end of approximately one year, the efficiency has fallen by 15% and it is therefore necessary to clean the precipitation cartridges. A consideration has also been made on the possibility to equip an entire subway station. According to the results obtained, about twenty filters placed in the top of a non mechanically ventilated station would permit to half an initial concentration in particles of 230 microg m(-3).
Air Pollution↗
Particulate matter emissions during transient locomotive operation: preliminary study.
Certification testing of locomotive diesel engines is conducted by testing the locomotive in a series of steady-state conditions, or notches. The aim of this work was to determine whether notch changes, which are made on the order of twice per minute during normal locomotive operation, significantly affect emission rates. Particulate matter (PM) measurements recorded by others over 5, 15, and 30 min immediately at notch change were analyzed. By assuming that PM emissions during steady-state conditions were constant, it was possible to determine the amount of PM emitted because of notch change. Certification line-haul and switching duty cycles were modified to include a representative number of notch changes. The results of these calculations suggest that in test cycles in which a representative number of notch changes were included, approximately 40% of PM emissions occurred because of notch changes.
Air Pollutants↗
Ergonomic diagnosis of the driver's workplace in an electric locomotive.
This paper deals with research aimed at developing a method for ergonomic analysis of the driver's workplace in an electric locomotive. It presents the structure of the diagnosis and its assumptions, and includes a re-evaluation of the questionnaire-expert method in ergonomic research. The article presents research data on weights and evaluations including their standard deviations for particular priority features. Ergonomic levels of the studied operator's cabin in locomotives are compared.
Equipment Design↗
Laterality and accident proneness: a study of locomotive drivers.
This study attempted to find the association between four measures of laterality (handedness, footedness, eyedness, and earedness) and accident proneness in locomotive drivers. The Sidedness Bias Schedule was administered to a sample of 80 locomotive drivers to ascertain their preferential bias. Their accident records were also available. Positive correlations were mostly found between the measures of hand, foot, ear, and eye dominance. Analyses suggested that there was a higher accident rate among left-handers and left-footers, with multiple regression unable to determine whether handedness or footedness was related more strongly to accident proneness. However, it was clear that accident rate was primarily associated with direction of lateralisation, and not with degree of lateralisation. Drivers with left-handedness were more likely to be involved in accidents, and it is possible that that may be related to the design of the locomotive cabs.
Accident Proneness↗
Whole-body vibration exposure: a comprehensive field study.
A comprehensive field study investigated whole-body vibration exposure levels experienced by the train operators of a large metropolitan subway system. The purposes of the study were to measure mechanical vibrations transmitted to the seated train operators, to calculate daily whole-body vibration exposure levels, and to compare these levels with maximum acceptable exposure levels recommended by the international standard on whole-body vibration (ISO 2631). The study also sought to identify factors that may influence mechanical vibrations transmitted to the operators and quantify their effects on the measured vibration levels. The study was carried out by dividing the subway system into subway lines, each line into southbound and northbound directions, and each direction into station-to-station observations. Triaxial measurements were made on all subway lines and for all car types used in the system. For each line, at least two round trips of data were collected. Time-weighted averages of the two sets of data were used for final presentation. A total of 48 round trips were made and more than 100 hours of vibration data was collected and analyzed. All phases of the study were carried out in accordance with the procedures outlined in ISO 2631. It was determined that 6 out of 20 subway lines had vibration levels higher than daily exposure limits recommended by ISO 2631. It was also determined that train speed was the most significant factor influencing vibration exposure levels.
Humans↗
Estimating magnetic field exposures of rail maintenance workers.
A measurement survey was undertaken to estimate exposures to 25 hertz (Hz) magnetic fields of maintenance workers on electrified rail lines near Philadelphia, Pa. Because of the mix of frequencies expected, a strategy was developed using new instrument to capture magnetic field waveforms, which were then analyzed by fast Fourier transform for their frequency components. This instrument could only take spot measurements, so a personal monitor repeatedly measured magnetic fields in the ranges of 40-100 Hz. To power trains in the mid-Atlantic region, electrical current flows from the overhead catenary to the locomotive and returns through the rails in a loop up to 10 miles long. This flowing current was the primary source of the magnetic field exposures when a train was near the maintenance work site being measured. A total of 93 spot measurements was taken at five locations. Peak magnetic flux densities ranged from 34 to 185 milligauss (mG) near a transformer, while medians at the five locations ranged from 6.5 to 40 mG. Time-weighted average personal exposures were estimated by combining spot measurements at occupied locations, with estimates of how much time was spent at each location. These averages were estimated to lie between 3.0 and 18 mG, depending on the location of how often trains passed the work site. Comparisons between the spot measurements in the 40-100 Hz frequency range and summarises from the personal dosimeter showed reasonably good agreement. Further characterization of personal exposures in this region may be justified, since on-train workers and passengers may be more highly exposed.
Bias↗
Dust in the underground railway tunnels of an Italian town.
This article assesses hazards associated with exposure to dust in tunnels and platforms of the A and B lines of Rome's underground railway and provides an informed opinion on the risks to workers and the travelling public of exposure to tunnel dust. The study focused on the analysis and measurement of dust granulometric classes PM10, respirable fraction, respirable combustible dust, and the organic, metallic, siliceous, and fibrous components. Comparing the measurement values from the tunnels and platforms with those found at the entrances to the underground railway stations, it emerges that dust concentration in the tunnels and platforms is three times higher, with a maximum PM10 value of 479 microg/m3. Averaged over 24 hours, in relation to the above ground levels, drivers and station staff are exposed to an additional value of 11 microg/m3 and 10 microg/m3, respectively. If commuters were to remain in the trains or on the station platforms, the 24-hour average exposure would increase by 3 microg/m3. Iron and silica were the major components found in the dust. The use of silica sand in the emergency braking system of the carriages is capable of causing a dispersion of quartz in the air in percentages varying from 5% to 14%. Methods are suggested in this article for the reduction of dust dispersion.
Air Pollutants↗
Alcohol as a risk factor for unintentional rail injury fatalities during daylight hours.
Railway fatalities account for approximately 10% of transport fatalities in Cape Town. The objective of this study was to examine alcohol intoxication as a risk factor during daylight hours by conducting a case - control study to compare rail passenger and pedestrian fatalities (cases) with motor vehicle passenger and pedestrian fatalities (controls). Rail passenger and rail pedestrian fatalities were defined as cases with motor vehicle passenger and pedestrian fatalities as the respective controls. Data were collected from post-mortem reports at two mortuaries from 1994 to 1996. Blood alcohol concentration was the dependent variable. The independent variables were age, gender, date of death, day of week, time of injury and external cause of death. The late afternoon and early evening period from 1600 hours to 1900 hours had the highest frequency of fatalities for all case and control groups. Of the 56 predominately male (89%) railway passenger cases with an average age of 34.5 (SD 12.5) years, Friday (27%) was the most frequent day of death. Railway pedestrian cases (89% male, average age 36.8 years (SD 13.3)) were more likely to be killed on a Monday (11% of cases). Among the controls, motor vehicle passengers (63% male, average age 39.9 (SD 15.5)) were more likely to die on a Sunday (25%) and pedestrians (82% male, average age 41 (SD 14.7)) on a Saturday (21%). The study showed that alcohol consumption is an important risk factor for rail fatalities during daylight hours, with rail passenger fatalities being 4.71 (1.72 - 12.88) and rail pedestrian fatalities 1.62 (0.98 - 2.69) times more likely to be intoxicated than the respective controls. The results provide more evidence for public health campaigners to tackle endemic alcohol abuse and to develop diverse interventions that do not exclusively target motor vehicle drivers.
Accidents↗