Panagiotis Mitropoulos

Cognitive Approach to Construction Safety: Task Demand-Capability Model

In the evolution of safety research, the literature identifies three paradigms: normative, error-based, and cognitive engineering. Traditionally, strategies to improve construction safety have been based on the normative paradigm—compliance with prescribed safety rules. However, the normative approach ignores how the characteristics of the production system and team processes influence the work behaviors and the possibility of errors and accidents. These factors are the focus of the cognitive engineering perspective. This study develops a cognitive model of construction safety, which conceptualizes safety as an emergent property of the production system. The model proposes that during a task, the task demands and the applied capabilities determine the potential for errors and accidents. It also proposes that the production practices and the teamwork processes of the crew shape the work situations that the workers face—that is, the task demands and the applied capability. Empirical evidence from recent cas...

New Method for Measuring the Safety Risk of Construction Activities: Task Demand Assessment

The task demand assessment (TDA) is a new technique for measuring the safety risk of construction activities and analyzing how changes in operation parameters can affect the potential for accidents. TDA is similar to observational ergonomic methods—it does not produce estimates of probabilities of incidents, but it quantifies the “task demand” of actual operations based on characteristics of the activity and independent of the workers’ capabilities. The task demand reflects the difficulty to perform the activity safely. It is based on (1) the exposure to a hazard and (2) the presence and level of observable task demand factors—that is, risk factors that can increase the potential for an accident. The paper presents the findings from the initial implementation of TDA and demonstrates its feasibility and applicability on two different operations: a roofing activity and a concrete paving operation. Furthermore, the paving case illustrates how the TDA method can compare different production scenarios and meas...

Team Processes and Safety of Workers: Cognitive, Affective, and Behavioral Processes of Construction Crews

AbstractHigh-risk sectors emphasize teamwork as a key strategy for systematic error management and accident prevention. In the construction sector, however—a sector that accounts for 6% of the employment and 20% of the occupational fatalities in the United States—current theories and practices of accident prevention ignore the important role of team processes. This study investigates the team processes that influence construction workers’ safety, and discusses the challenges in developing effective teamwork in construction crews. The paper first summarizes the literature on team performance with a focus on construction work groups. The review identifies the key cognitive, affective, and behavioral components of teamwork affecting workers, safety. These teamwork components provide the criteria for evaluating the attributes of construction operations and context that create challenges to effective teamwork at the production level. This discussion also reviews practices that construction supervisors use to i...

Safety as an Emergent Property: Investigation into the Work Practices of High-Reliability Framing Crews

With regards to safety, the challenge for researchers and practitioners is to develop work systems that can achieve at the same time high levels of productivity and safety. Towards this objective, this research investigates the work practices of high-reliability crews—that is, crews who perform high-risk work with exceptionally high productivity and safety. The objective of the research is to increase understanding of the work practices that reduce the likelihood of accidents while at the same time increase productivity. This paper presents the findings of an initial exploratory study that compares the work practices of two residential framing crews: one crew with consistently exceptional levels of safety and productivity, and one average-performing crew from the same company. The two crews did not show any difference in safety practices—both crews had high compliance with the company’s safety requirements. However, the production practices of the high-reliability crew were shaped by a clear “guiding prin...

Task Demands in Masonry Work: Sources, Performance Implications, and Management Strategies

AbstractConstruction work involves significant physical, mental, and temporal demands. High task demands increase the likelihood of errors, with implications for rework, safety, and productivity. To ensure the safety and productive efficiency of workers, it is important to better understand the task demands and manage them effectively. This exploratory study investigated the task demands in masonry work, the factors that generate the demands, the influence of demands on performance, and the practices that field supervisors use to manage/regulate them. Data were collected on two masonry projects. The NASA Task Load Index (TLX) was used to measure the workers’ subjective assessment of task demands. The members of masonry crews perceived different type and level of task demands depending on their role—supervisor, masons, laborers, and operator. Interviews with the crew members identified design features and work practices that influenced the task demands. Extensive field observations identified three strateg...

Analysis of Residential Framing Accidents, Activities, and Task Demands

Framing contractors have the highest rate of nonfatal incidents among specialty contractors. This case study analyzes 654 safety incidents that occurred over a period of 5 1 2  years in a large residential framing company. Accident analysis and interviews with safety and production experts identify the high-risk tasks, the errors that lead to incidents, and the task factors that increase the likelihood of incidents. The analysis resulted in a framework of five task factors that increase the task demands: (1) working platform constraints; (2) ergonomic postures constraints; (3) material/load handling requirements; (4) tool use/accuracy requirements; and (5) difficulties due to external forces. The combined effect of these factors determines the task difficulty and the likelihood of incidents. The paper discusses safety measures to reduce the task demands of the high-risk tasks, as opposed to measures that reduce exposure or mitigate the consequences. Reducing task demands can reduce the likelihood of accid...

Critical Concerns of Production Control System on Projects with Labor Constraints: Lessons from a Residential Case Study

Labor constraints and schedule pressures are common in periods of high market growth. Such conditions can have a significant impact on project performance. However, the extent to which such conditions impact the project depends on the effectiveness of the production control system. This case study analyzes the performance problems on a large residential project with significant labor constraints. The case first describes how the combination of labor shortage, high workload, and quality problems caused extensive workflow disruptions and schedule delays. Then, the analysis discusses why the production control system (the way the work assignments are planned, coordinated, and released for execution) failed to effectively manage these problems. The case is based on data from nine single-family houses in a large residential development. To evaluate the production control system, the authors used lean construction metrics and collected detailed data on the activities completed every week, the activities that we...

Rethinking Safety: Learning To Work Near The Edge

Construction safety has substantially improved, but has reached a plateau. A breakthrough transcending “Best Practice” is required. This paper considers current “Best Practice” to reveal its underlying theoretical assumptions. An alternative theory is proposed, based on the work of Jens Rasmussen, a leading thinker on risk management in dynamic environments. A research program is put forward to test and develop a new approach to safety management.

A Framework of Teamwork Attributes Affecting Workers Safety

In recent decades, several sectors of the economy (aviation, shipping, power generation, healthcare, etc.) have emphasized teamwork as a key strategy for systematic error management and accident prevention. This study focuses on the role of team processes in the safety of construction work groups. The paper first reviews the key teamwork constructs (cognitive, affective and behavioral attributes of teams) and develops a framework of teamwork attributes that are important for safety. This framework is based on an extensive review of the teamwork literature from several disciplines and sectors. Then, the framework is used to identifies the teamwork challenges in the context of construction operations. Finally the paper provides directions towards systematic improvement of the teamwork processes in construction crews.

ACCIDENT PREVENTION STRATEGIES: CAUSATION MODEL AND RESEARCH DIRECTIONS

This paper presents an accident causation model that identifies the production system factors affecting the accident process, and proposes accident prevention strategies. The model builds on descriptive rather than prescriptive theories of work behavior and acknowledges the inevitability of exposures and errors. It also focuses on the operation as the level of analysis—that is, it focuses on the factors that influence the number of accidents during a construction operation. The model first identifies the production factors that affect the frequency of hazards during a construction activity, and emphasizes the importance of task unpredictability. Then we examine how the production pressures and the tendency to minimize effort increase the workers’ efficient behaviors and their exposure to hazards, while safety efforts try to prevent such exposures. Finally, the model acknowledges that exposure to hazards only leads to accidents, if errors or changes in the situation “release” the hazard. Based on this conceptualization of the accident process, the paper proposes accident prevention strategies that do not focus on compliance with safety rules: (1) reduce task unpredictability to reduce the frequency of hazards; (2) improve the work conditions to enable more productive behaviors without increasing the safety risk, and (3) develop error management strategies to prevent, trap and mitigate the consequences of errors. These strategies provide direction for safety research.