The wood-framing trade has not sufficiently been investigated to understand the work task sequencing and coordination among crew members. A new mental framework for a performing crew was developed and tested through four case studies. This framework ensured similar team performance as the one provided by task micro-scheduling in planning software. It also allowed evaluation of the effect of individual coordination within the crew on the crew's productivity. Using design information, a list of micro-activities/tasks and their predecessors was automatically generated for each piece of lumber in the four wood frames. The task precedence was generated by applying elementary geometrical and technological reasoning to each frame. Then, the duration of each task was determined based on observations from videotaped activities. Primavera's (P6) resource leveling rules were used to calculate the sequencing of tasks and the minimum duration of the whole activity for various crew sizes. The results showed quick convergence towards the minimum production time and allowed to use information from Building Information Models (BIM) to automatically establish the optimal crew sizes for frames. Late Start (LS) leveling priority rule gave the shortest duration in every case. However, the logic of LS tasks rule is too complex to be conveyed to the framing crew. Therefore, the new mental framework of a well performing framer was developed and tested to ensure high coordination. This mental framework, based on five simple rules, can be easily taught to the crew and ensures a crew productivity congruent with the one provided by the LS logic. The case studies indicate that once the worst framer in the crew surpasses the limit of 11% deviation from applying the said five rules, every additional percent of deviation reduces the productivity of the whole crew by about 4%.

Construction work is ergonomically hazardous, as it requires numerous awkward postures, heavy lifting and other forceful exertions. Prolonged repetition and overexertion have a cumulative effect on workers often resulting in work related musculoskeletal disorders (WMSDs). The United States spends approximately $850 billion a year on WMSDs. Mechanical installation workers experience serious overexertion injuries at rates exceeding the national average for all industries and all construction workers, and second only to laborers. The main contributing factors of WMSDs are ergonomic loads and extreme stresses due to incorrect postures. The motivation for this study is to reduce the WMSDs among mechanical system (HVAC system) installation workers. To achieve this goal, it is critical to reduce the ergonomic loads and extreme postures of these installers. This study has the following specific aims: (1) To measure the ergonomic loads on specific body regions (shoulders, back, neck, and legs) for different HVAC installation activities; and (2) To investigate how different activity parameters (material characteristics, equipment, workers, etc.) affect the severity and duration of ergonomic demands. The study focuses on the following activities: (1) layout, (2) ground assembly of ductwork, and (3) installation of duct and equipment at ceiling height using different methods. The researcher observed and analyzed 15 HVAC installation activities among three Arizona mechanical contractors. Ergonomic analysis of the activities using a postural guide developed from RULA and REBA methods was performed. The simultaneous analysis of the production tasks and the ergonomic loads identified the tasks with the highest postural loads for different body regions and the influence of the different work variables on extreme body postures. Based on this analysis the results support recommendations to mitigate long duration activities and exposure to extreme postures. These recommendations can potentially reduce risk, improve productivity and lower injury costs in the long term.