Within the construction industry, proximity of actual to scheduled completion time is a primary performance measure, and deviations from planned schedules remain a popular concern in the field of construction management. Prevailing research assumes that delays arise either from flawed execution of the plan or from failure to plan effectively. Thus, solutions suggested include improving execution and developing ever more sophisticated planning techniques. In spite of these efforts, accuracy in scheduling construction projects has shown little or no improvement, and clients continue to incur the significant costs associated with the failure to more accurately plan. Eschewing this traditional techno-rational view, the current research turned to critical management studies for solutions and investigated planning intentionality, the intentional and unintentional roles planners play in project delays. Thus, it sought to explore the following with respect to the project planner role: optimism bias, where a planner unintentionally mitigates negative information in decision-making; strategic misrepresentation, where a planner intentionally mitigates negative information; and group dynamics in time estimation. The latter is relevant because a team rather than an individual typically embodies the planner function within a construction project. To perform this research, two mixed-methods studies, preceded by a pilot study, and seven interviews with project planners were conducted. The first mixed-methods study investigated how intended and unintended actions of participants affected underestimation of time during task performance; and the second investigated the creation of collective intentionality, the transmutation of individual preferences into a group consensus in time estimation. Results of the first mixed-methods study identified the key situational variables differentiating intended and unintended actions of planners and indicated how these can influence the quality of time estimation. Results of the second study showed that group performance in time estimation was inferior to that of individuals and that group member interaction appeared detrimental to good decision-making. Reasons found were sense of power, commitment, confidence level, cultural diversity, conflicts, and groupthink. The findings were compared and contrasted with those obtained from interviews with project planners to enhance the scope of the study.

Cost Overrun is something that plagues infrastructure projects, both in Sweden and globally. The repercussion of it can be severe since it not only hurts the public’s perception of how the public authorities manage and allocates its resources, but also due to the immense opportunity costs that arise when the increased costs need to be covered. In general, the factors that lead to cost overrun in infrastructure transport projects can often be derived from technical, psychological, political, and economical factors, and it is not uncommon that there is a combination of these factors, which is why the subject of cost overrun is so complex. With a highly unique dataset, this paper examines cost overrun in Swedish infrastructure transport projects to see if there is a statistical relationship between cost overrun and the size of a project, its regional location, and whether it is a road- or railway project. Furthermore, an evaluation of the process of estimating and forecasting costs will be conducted. The results shows that the characteristics of regional locations have a significant relationship with projects experiencing cost overrun and that cost overrun is more common in smaller projects. There were no significant differences in cost overrun between types of projects, but it was found that between the period 2018 to 2022, cost estimates had been underestimated by approximately 34%.