## 5 Conclusions  
This study provides four theoretical contributions that advance the understanding of schedule planning in road intersection construction projects. First, it offers a structured identification of 29 planning processes and their primary data inputs obtained through a systematic literature review of 22 documents. Second, it proposes a theoretical framework that organizes these processes into five planning stages, aligned with the PMBOK structure and validated by a panel of five industry experts, thus contributing to the formalization of scheduling practices. Third, it introduces an original analytical model that associates 22 causes of planning deficiencies with the five stages, based on insights gathered from semi-structured interviews with ten professionals. Fourth, it presents an empirical validation of the model by analyzing 25 road intersection projects, using Qualitative Comparative Analysis (fsQCA) to identify causal patterns linked to schedule and cost deviations. The study highlights those certain deficiencies, such as deficient material estimation, lack of planner experience, omission of WBS, and insufficient consideration of road markings, consistently contribute to negative project outcomes. These findings deepen the theoretical foundation of construction planning by linking structured planning stages, deficiency causes, and their measurable impacts on project performance. This analysis is structured in two parts to contribute new insights into the relationship between planning deficiencies and project performance. The first part quantitatively compares cost deviations (CD) and schedule deviations (SD) in projects affected and unaffected by specific deficiencies, identifying measurable impacts. The second part applies fuzzy-set Qualitative Comparative Analysis (fsQCA) to explore how combinations of deficiency influence these deviations. The results demonstrate that certain deficiencies, specifically, deficient estimation of material quantities (C6), lack of experience of the planner (C\({}_{10}\)), omission or deficiency in the definition of work packages (C\({}_{13}\)), and omission of road markings in planning (C\({}_{16}\)), emerge as necessary conditions with high consistency scores for producing cost overruns and delays. This dual-level analysis contributes to the academic literature by offering empirical evidence that links specific deficiencies to quantifiable project outcomes. It advances theoretical understanding by identifying critical configurations of planning shortcomings that systematically affect performance. Furthermore, the study offers a predictive framework for anticipating how deficiencies in schedule planning contribute to negative outcomes, thus bridging the gap between theoretical planning models and the realities of project execution. The practical applications of the theoretical contributions of this study offer significant improvements in scheduling planning for road projects. Professionals can gain a clear understanding of critical processes that require attention to minimize delays and cost overruns in road intersection projects. By identifying and associating planning processes with specific deficiency causes, project managers can implement targeted mitigation strategies to enhance schedule execution and improve the accuracy of time and cost estimates. This evidence-based practical approach facilitates decision-making that is aligned with PMBOK standards, which is crucial for the success of road infrastructure projects in complex and dynamic contexts. Analyzing the consequences of deficiency causes in 25 road intersection projects identified in public contracts holds practical value for road construction industry professionals. By thoroughly examining the minutes and technical documents generated during the execution of these projects, the study provides a precise and well-founded understanding of how and why delays and cost overruns occur.