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The interplay between formal and informal elements in analysing situations of role conflict among construction participants The interplay of formal and informal factors in construction teams influences the enactment of roles and the individuals who fulfil those roles. With a specific focus on a phenomenon called role conflict, the aim is to explore if and how the interaction of formal and informal elements would lead to situations of role conflict. This phenomenon proved to lead to frustration, tension and employee burnout. An analytical model of role interaction was developed, which disentangles formal and informal elements that shape role interactions. Qualitative data was collected through semi-structured interviews, project documents and observations. Four cases of role conflict are presented here. Contract, as a formal element, and participant's values and interests, as informal elements, appeared to be the most important factor shaping participants' expectations and behaviours. The analysis in this study showed that if a participant who faces role conflict is able to influence the formal elements in favour of his or her informal elements, then he or she may experience less frustration. At a more general level, the results suggest that increasing formality can increase participants' frustration, which then would decrease the likelihood of collaboration. As the theoretical contribution, this research extends organisational role theory to deal with informal and formal aspects. Taking into account formal sources enables the study of how roles are institutionally governed while including informal sources allows for the idea that some of the aspects of the role, even in the context of work role, are socially constructed.

Project execution is often delayed by extreme and unforeseen weather conditions. This is because extreme weather usually causes work disruption, waste of resources, significant project delays and, eventually, financial losses for both the contractor and the project owner. Construction contracts generally include weather-related clauses addressing when, and to what extent, the responsibilities and consequences of adverse weather are to be shared or compensated. However, setting clear and objective limits for abnormal weather is problematic, starting with the lack of agreement about which weather conditions can be considered as "normal" or "average”. Research on the influence of weather on construction productivity is scarce and underdeveloped. Therefore, practitioners cannot count on sound methods to mediate in and evaluate weather-related contract disputes. In these situations, claims are likely to arise and escalate. A stochastic model for objectively evaluating the weather influence during the execution stage is proposed. This model allows actual weather to be compared to historical data in a way that provides an objective assessment of the extent to which the adverse weather was (or not) exceptional. A case study of a fictional project is used to show its implementation. This is the first tool of its kind to address this concern with a straightforward, holistic and quantitative approach.

Poor urban air quality is one of the most pressing environmental problems, and the rapid growth in the number of motor vehicles is a major contributor to it. To tackle this problem, low emission zones (LEZs) were introduced and they have been applied in many of the mega cities around the world. Yet, a scientific approach to design the boundaries of LEZs is missing. This study develops an innovative model to address this gap, using total vehicle kilometers traveled (VKT) as the basis. The model allows defining and/or optimizing the LEZ boundaries. It is applied for the Tehran metropolitan area, as a case study, and the results show the optimality of the existing LEZ boundaries; however, they challenge the efficiency of the proposed policies on modifying current boundaries.