PurposeAlthough several studies have been conducted on the causes of cost overrun, they have mainly assumed that the causes of cost overrun are independent of each other, and few of them scrutinized the complex interrelationships between the causes. To fill the gap, this study aims to investigate the mutual interactions between the causes of cost overrun using interpretive structural modeling (ISM) and proposing strategies to tackle the causes considering their interactions.Design/methodology/approachCritical causes of cost overrun were identified through a comprehensive literature review. In total, 22 key causes are then refined based on the opinions of relevant experts involved in the Iranian building and construction sector. Using the nominal group technique, the causes' interactions were examined and represented via the ISM diagram. The causes were also classified using “matrix cross-reference multiplication applied to a classification (MICMAC)” technique.FindingsThe results showed that price fluctuation, claims, execution delay, delay in payment and change order positioned at the highest level of the obtained model can directly result in cost overrun, and corruption and poor contract management located at the base of the model are two major root causes of cost overruns. It was also concluded that more attention should be paid to the precontract phase of the project to address and prevent corruption and managerial issues deeply rooted in this stage.Originality/valueThe findings of this study provide a clear understanding of how different causes of cost overrun are related to each other and can ultimately assist project managers of different parties in choosing strategies to mitigate cost overrun in building construction projects.

Purpose Poor quality of design documents and Design Deficiencies (DDs) are critical factors that can potentially cause time and cost overrun and lead to project failure. Despite the importance of this issue, few studies have been conducted to explore the underlying relations among the causes and effects of DDs, and it is not clear how they exert influence on each other. However, it is imperative to have a clear understanding of their interrelationships so as to devise intervention strategies. The purpose of this study is, therefore, to explore these causes and effects. Design/methodology/approach To this aim, a qualitative system dynamics model was provided to visualize how various factors interact with one another. The model was developed and validated by drawing on the expertise of industry-related experts. The key causes and effects of the DDs were identified through the investigation of the model. Findings It was concluded that design management of project and the composition of design teams are critical. The obtained results also showed that more attention should be paid to the enhancement of knowledge circulation and communication within design firms and increasing the awareness of managers and owners from the technical consequences of their managerial decisions. Research limitations/implications It is worth mentioning that the design process could be deeply affected by the quality, frequency and strength of relationships among the project’s parties. Early involvement of contractors, for example, can significantly contribute to enhancing design quality. This study investigates factors’ interactions in projects delivered using the traditional design-bid-build method. As relationships between the project’s parties could be different in various project delivery methods, further research is indeed needed to assess factors’ interactions in projects delivered using other methods. Originality/value It is believed that the proposed model by providing a better insight into the connections of causes and effects could aid project managers of different parties with planning the strategies to reduce DDs and mitigate their effects.

PurposeThe purpose of this study is to investigate the latent interrelationships of causes and effects of design deficiencies (DDs) and to identify the most crucial ones by considering the interactions among them.Design/methodology/approachFirst, through a comprehensive literature review, the most critical causes of DDs were identified. The review eventuated in a list of 22 causes and 12 effects, which were categorized into six groups. Second, through the rules of system dynamics and the interactions between the causes and effects were modeled and illustrated using causal loop diagrams (CLDs). With the aid of semi-structured interviews with 20 competent experts, the resultant CLDs were also validated. Third, the opinions of 54 experts, who were chosen from the Iranian community of clients and consultants, were solicited concerning the degree of influence which each factor (causes or effects) exerts on others. Finally, the social network analysis (SNA) approach was deployed to analyze and prioritize factors based on the gathered data from experts.FindingsSNA results indicated that factors such as “design firms' staff rework” and “design firms' loss of reputation” are the most central factors affecting DDs. The model results also identified that factors such as “schedule variance”, “workload” and “lack of quality control and supervision during the design phase” have the highest overall impact on DDs. In the end, some recommendations to address major factors and links were also put forward. Overall, more communications between the pair of stakeholder groups and continuous learning from project experiences are believed to be the main strategies.Originality/valueIt is believed that this study has provided a comprehensive understanding of causal mechanisms among factors, which can assist project managers of different parties (clients, contractors and consulting firms) in taking more effective actions to ameliorate the quality of design documents.