Delays in quay construction projects can have significant consequences for project duration, cost, quality, and overall project performance. Therefore, identifying and evaluating the factors contributing to delays plays an important role in improving project management and mitigating their adverse consequences. The present study was conducted with the aim of identifying and evaluating the factors affecting delays in quay construction projects in southern Iran. In terms of its objective, this study is developmental-applied, while methodologically it employs a combination of qualitative and quantitative approaches. In the qualitative phase, the factors and components affecting project delays were identified through library research and in-depth, semi-structured interviews with experts using thematic analysis, and the conceptual model of the study was developed. In the quantitative phase, the proposed model was evaluated and tested using questionnaire data collected from 217 managers and employees involved in quay construction projects in southern Iran through Confirmatory Factor Analysis (CFA) and Structural Equation Modeling (SEM). The findings of the qualitative phase indicated that the factors affecting delays in quay construction projects in southern Iran can be classified into six main factors: contextual factors, organizational strategies, organizational factors, marketing factors, structural factors, and environmental factors, comprising a total of 31 components. The results of the quantitative phase also showed that all six factors have a direct and significant effect on delays in quay construction projects. Furthermore, the results of the validity and model-fit indices indicated adequate sample size, appropriate construct validity, and an acceptable fit of the proposed conceptual model. Based on the findings, simultaneous consideration of organizational, structural, environmental, contextual, marketing, and organizational strategic factors can contribute to the timely identification of delay risks and improve time management in quay construction projects.