Victor Paquet

PATH: a work sampling-based approach to ergonomic job analysis for construction and other non-repetitive work.

A high prevalence and incidence of work-related musculoskeletal disorders have been reported in construction work. Unlike industrial production-line activity, construction work, as well as work in many other occupations (e.g. agriculture, mining), is non-repetitive in nature; job tasks are non-cyclic, or consist of long or irregular cycles. PATH (Posture, Activity, Tools and Handling), a work sampling-based approach, was developed to characterize the ergonomic hazards of construction and other non-repetitive work. The posture codes in the PATH method are based on the Ovako Work Posture Analysing System (OWAS), with other codes included for describing worker activity, tool use, loads handled and grasp type. For heavy highway construction, observations are stratified by construction stage and operation, using a taxonomy developed specifically for this purpose. Observers can code the physical characteristics of the job reliably after about 30 h of training. A pilot study of six construction laborers during four road construction operations suggests that laborers spend large proportions of time in nonneutral trunk postures and spend approximately 20% of their time performing manual material handling tasks. These results demonstrate how the PATH method can be used to identify specific construction operations and tasks that are ergonomically hazardous.

Reliable exposure assessment strategies for physical ergonomics stressors in construction and other non-routinized work

The objective of this research was to provide guidelines for the reliable assessment of ergonomics exposures in non-routinized work. Using a discrete-interval observational sampling approach, two or three observers collected a total of 5852 observations on tasks performed by three construction trades (iron workers, carpenters and labourers) for periods of several weeks. For each observation, nine exposure variables associated with awkward body postures, tool use and load handling were recorded. The frequency of exposure to each variable was calculated for each worker during each of the tasks on each of the days. ANOVA was used to assess the importance of task in explaining between-worker and within-worker variability in exposures across days. A statistical re-sampling method (bootstrap) was used to evaluate the reliability of exposure estimates for groups of workers performing the same task for different sampling periods. Most exposures were found to vary significantly across construction tasks within trade, and between-worker exposure variability was generally smaller than within-worker exposure variability within task. Bootstrapping showed that the reliability of the group estimates exposure for the most variable exposures within task tended to improve as the assessment periods approached 5 – 6 d, with marginal improvements for longer assessment periods. Reliable group estimates of exposure for the least variable exposures within task were obtained with 1 or 2 d of observation. The results of this study demonstrate that an initial estimate of the important environmental or task sources of exposure variability can be used to develop an efficient sampling strategy that provides reliable estimates of ergonomics exposures during non-routinized work.

Quantification of Ergonomic Hazards for Ironworkers Performing Concrete Reinforcement Tasks During Heavy Highway Construction

A study was conducted to assess the ergonomic hazards of ironwork job tasks associated with concrete reinforcement work at a large highway construction site. PATH (posture, activity, tools, and handling) analysis, a work-sampling method, was used to provide task-based estimates of the percentage of time ironworkers spent in specified postures of the trunk, arms, and legs; performed activities; used tools; and handled loads. A total of 2128 PATH observations were made of 17 ironworkers performing 5 job tasks: (1) ground-level reinforcement bar (rebar) construction, (2) wall rebar construction, (3) ventilation rebar construction, (4) preparation work, and (5) supervising. Nonneutral trunk postures were observed frequently (exceeding 30%) and manual material handling (MMH) was the most commonly observed activity (exceeding 20%) for all job tasks except supervising. The percentage of time workers spent in specific postures, activities performed, tool use, and MMH activities differed significantly between the five main job tasks, even when supervising was excluded from the analysis. It was concluded that ironworkers are exposed to significant ergonomic hazards when performing concrete reinforcing tasks, and that opportunities exist for the implementation of ergonomic interventions. Further, the results of this study can be used to target specific hazardous tasks for ergonomic interventions and confirms the need to use a task-based exposure assessment strategy to properly assess ergonomic risk profiles for nonstructured jobs such as construction.

The ability of limited exposure sampling to detect effects of interventions that reduce the occurrence of pronounced trunk inclination

Ergonomics interventions often focus on reducing exposure in those parts of the job having the highest exposure levels, while leaving other parts unattended. A successful intervention will thus change the form of the job exposure distribution. This disqualifies standard methods for assessing the ability of various exposure measurement strategies to correctly detect an interventions effect on the overall job exposure of an individual worker, in particular for the safety or ergonomics practitioner who with limited resources can only collect a few measurements. This study used a non-parametric simulation procedure to evaluate the relationship between the number of measurements collected during a self-paced manufacturing job undergoing ergonomics interventions of varying effectiveness, and the probability of correctly determining whether and to which extent the interventions reduced the overall occurrence of pronounced trunk inclination, defined as an inclination of at least 20 degrees . Sixteen video-recordings taken at random times on multiple days for each of three workers were used to estimate the time distribution of each workers exposure to pronounced trunk inclination. Nine hypothetical ergonomics intervention scenarios were simulated, in which the occurrence of pronounced trunk inclination in the upper 1/8, 1/4, and 1/2 of the job exposure distribution was reduced by 10%, 30% and 50%. Ten exposure measurement strategies were explored, collecting from one to ten pre- and post-intervention exposure samples from an individual worker. For each worker, intervention scenario and sampling strategy, data were bootstrapped from the measured (pre-intervention) and simulated (post-intervention) exposure distributions to generate empirical distributions of the estimated intervention effect. Results showed that for the one to three intervention scenarios that had the greatest effect on the overall occurrence of trunk inclination in the job, one to four pre- and post-intervention measurements, depending on worker, were sufficient to reach an 80% probability of detecting that the intervention did, indeed, have an effect. However, even for the intervention scenario that had the greatest effect on job exposure, seven or more samples were needed for two of the three workers to obtain a probability larger than 50% of estimating the magnitude of the intervention effect to within +/-50% of its true size. For almost all interventions affecting 1/8 or 1/4 of the job, limited exposure sampling led to low probabilities of detecting any intervention effect, let alone its correct size.

Making sense of highway construction: A taxonomic framework for ergonomic exposure assessment and intervention research

Construction is one of the most hazardous industries in the United States. Occupational health research to characterize the hazards in construction work has been hampered by the lack of a systematic approach to classification of construction work and its associated hazards. A taxonomy of construction work, a nested system of classification, has been developed to systematize the collection and reporting of exposure assessment data for the characterization and reduction of hazards and the prevention of musculoskeletal injury. This taxonomy subdivides construction work into the categories of stage, operation, task, and activity. It is based on a bidding specification system already in use within the industry and thus provides a terminology common among workers, supervisors, and managers. The identification of tasks and activities that are present in multiple stages and/or trades contributes to the efficiency of exposure data collection and facilitates the generalizability to other settings for both exposure data and intervention evaluations. The taxonomy provides a framework and vocabulary that facilitates field work and participatory research activities. It can also potentially be linked to personnel and economic data for estimation of costs of safety and health problems, as well as benefits of interventions. Although developed for construction ergonomics, the taxonomic approach has application to non-routine work in other industry sectors and possibly in occupational health research other than ergonomics.

Variability in Risk Factors for Knee Injury in Construction

This study investigated sources of variance in exposure to risk factors for knee pain in a variety of highway construction trades, operations, and tasks. Over 15,000 discrete observations of leg postures and weights handled were made on 120 construction workers in five construction trades, in nine operations over 79 days. The contributions of trade, operation, task, and worker to the variability in work time spent kneeling, squatting, and carrying loads were evaluated with multilevel random effects models. Construction operation and task explained about 20% to 30% of total variation in kneeling, squatting, and carrying loads. There was a large unexplained component of variance thought to represent day-to-day variability of exposure within task. Reliable assessments of knee exposures require multiple days to accommodate the high variability of exposures among operations and tasks and over time. These sources of variability should be carefully considered in efforts to estimate exposures to knee loading for epidemiologic or intervention studies. Homogenous exposure groups are not easily defined from the readily available organizational features of construction work.

A tool for rapid assessment of product usability and universal design: Development and preliminary psychometric testing

BACKGROUND While there are many available tools and methods to evaluate product usability, few have been tested on user groups with disabilities and even fewer systematically consider universal design principles. OBJECTIVE This paper describes the development and preliminary psychometric testing of the Rapid Assessment of Product Usability & Universal Design (RAPUUD), a 12-item user-report tool based on the seven principles of universal design. METHOD A preliminary set of items was created to elicit ratings of diverse product characteristics (e.g., physical effort, cognitive effort, assistance required, safety). Data were gathered from 61 participants who rated the usability of products they use in their own environments. RESULTS Each item elicited a full range of responses, with no apparent floor or ceiling effects. Collectively, the 12 items achieved a high internal consistency (Cronbachs α=0.80). The data indicate that the tool was sensitive to differences in functional abilities, as well as differences in product characteristics. The instrument was usable for a range of consumer products, though not all items were appropriate for each and every product. CONCLUSION The results suggest that the instrument could become a pragmatic tool for designers to identify usability problems experienced by a diversity of user populations.

Predictive models of safety based on audit findings: Part 1: Model development and reliability.

This consecutive study was aimed at the quantitative validation of safety audit tools as predictors of safety performance, as we were unable to find prior studies that tested audit validity against safety outcomes. An aviation maintenance domain was chosen for this work as both audits and safety outcomes are currently prescribed and regulated. In Part 1, we developed a Human Factors/Ergonomics classification framework based on HFACS model (Shappell and Wiegmann, 2001a,b), for the human errors detected by audits, because merely counting audit findings did not predict future safety. The framework was tested for measurement reliability using four participants, two of whom classified errors on 1238 audit reports. Kappa values leveled out after about 200 audits at between 0.5 and 0.8 for different tiers of errors categories. This showed sufficient reliability to proceed with prediction validity testing in Part 2.

Space Requirements for Wheeled Mobility Devices

Research on the size of wheeled mobility devices in the UK and Canada suggests that the dimensions for “clear floor area” of wheeled mobility devices as specified in U.S. standards are too small. Anthropometric research was conducted to verify that findings in other countries are relevant for the U.S. Findings support increasing the clear floor area dimensions. To provide universal access to buildings, it is necessary to exceed the current requirements of minimum standards until they are revised to reflect the increased size of wheeled mobility devices.

Space Requirements for Wheeled Mobility Devices in Public Transportation: Analysis of Clear Floor Space Requirements

Recent research on the anthropometry of wheeled mobility devices and their users (n = 369) indicates that the current dimensions for clear floor area prescribed in U.S. accessibility standards for transportation are inadequate for accommodating many users of wheeled mobility devices, especially those who use power chairs and scooters. The current report presents anthropometry data for determining the dimensions of clear floor area on the basis of occupied device length and width to achieve a specified level of physical accommodation. The implications of the findings and the need to revise guidelines for accessible public transportation systems are discussed. The transportation industry as well as mobility device manufacturers, vendors, and prescribers should understand the limitations of current standards and become involved in the dialogue about how to improve them.