Constructability is a concept with relative and not absolute value to increase optimization capacity of resources such as workforce, time, cost, quality, and working environment conditions. Given the growing complexity of projects and the increased number of failed and abandoned projects, the necessity to implement constructability in projects has become more tangible. Although the effects of lack of quantitative definition of constructability role in the traditional construction approaches are evident and have led to lack of coordination in performance of construction projects, so far no comprehensive quantitative approach has been considered to analyze the obstacles to constructability implementation. This study aims to identify and categorize the obstacles to facilitating the presence of contractors in the early stages of planning and design to implement constructability. In this study a comprehensive list of obstacles to constructability implementation is developed as a questionnaire. This questionnaire was presented to the experts, active in the field of construction. Finally, its results were analyzed using exploratory factor analysis method. Totally, 63 obstacles were questioned, then they were categorized by some of the experts of this industry into five categories of macro factors, including contractual, environmental, managerial, technical, and organizational. The significance of this study is due to this fact that identifying and categorizing the key obstacles to constructability implementation provides a useful reference for managers and owners of the construction industry to identify and develop solutions to resolve them. Identifying the obstacles to the presence of contractors in the planning and design stage and having a quantitative view toward this issue affects project implementability. In this regard, one can present more effective solutions to facilitate the presence of contractors in the early stages of design and also improves the effectiveness of constructability.

Integrated Project Delivery (IPD) is introduced as a vibrant approach to enhance project implementation, having particular position in recent studies among construction researchers. This study analyzes the research trends on the field of IPD to provide an appropriate vision for future researchers in this specialized field. While so far no comprehensive research has been done in this field, this study provides a comprehensive review of existing studies through in-depth literature review method. This research evaluates studies conducted in the field of IPD, which is a basis for future researchers to improve conditions of IPD implementation in different countries. For that this study Using library studies, the trend of researches conducted on various concepts and domains during various years, has been investigated. Future studies can simply use the outputs of this research to shape their research flow on establishing continuing progress of IPD. The data obtained from descriptive analyses are illustrated quantitatively, followed by comprehensive analyses and discussion of the results. Moreover, this study concluded that during recent years, the trend of studies conducted about IPD has increased, particularly articles examined challenges. In the next step, more studies have been performed in the field of construction. Those articles are preferred that have evaluated principles, challenges, and solutions for resolving barriers. Proper IPD implementation facilitates enhanced share of information and early identification of stakeholders through a proper timing as vital keys to realize objectives of the construction projects, reduce risks, and increase the chance of project success.

Success in infrastructure projects requires success in all phases of the project, including design, construction, and operation. One of the necessary actions for developing countries to construct their economic infrastructures, is implementing infrastructure plans. This industry should focus more on the construction process and utilizing creative tools and new concepts for construction development. The reason of it is because of delivering the project with certain quality, in time and with the given budget. Contractors should have new strategies for construction to optimize project completion, and constructability. Accordingly, constructability improvements have become the concern of construction industry practitioners. Considering constructability issues in the early stages of the project enhances identifying design limitations that prevent capabilities of contractors to take part in planning and improving project performance. The purpose of this study is identifying the prerequisites of constructability to resolve the current problems of projects, including inappropriate plans without implementability, poor decision making in design, and lack of sufficient implementation experience in the design engineering team. This study provides a list of prerequisites for constructability implementation in infrastructure projects. Accordingly, it identifies the prerequisites, using Systematic Literature Review (SLR) technique. The NVivo software is used to facilitate the qualitative analyses.

The building sector in New Zealand is booming and currently very active, with a range of residential and commercial buildings being built in large cities. However, where there are major investments, problems, malfunctions, and errors become extremely costly and time consuming with significant implications on the success of projects. The current study focuses on causes of delay in building projects; in addition, the study sets out to investigate causes associated with or triggered by contractors within the construction phase. The emphasis is on causes that are more likely to create problems, conflicts, and disputes. A total of 14 types of delays were initially investigated through a review of relevant and high-impact sources. Accordingly, the causes of these delays were further investigated and verified via New Zealand building and construction experts. The discussions and analysis were extended beyond the causes and into response strategies and control of emerging issues and problems. The study suggests an action plan and spectrum of actions and strategies to avoid or mitigate the impact of the causes. This action plan is classified into proactive and reactive measures.

Having integrated contractual strategies for projects and developing a transparent and unambiguous contract is highly effective for properly implementation of constructability. This study uses integrated project delivery (IPD) as the most recent contractual delivery approach to facilitate easier constructability implementation in the construction industry. The aim of this study is to present a practical framework to reduce changes and duplications, and facilitate constructability through focusing on the IPD approach. A case study on mass housing projects in Tehran is applied to provide supportive research data. This study uses qualitative analyses of data from both literature and the case study. Previously, comprehensive studies have been done by the authors through conducting a meta-synthesis technique. Outputs of the study, which were barriers and solutions to facilitate constructability implementation, are used in this study as presumptions. Data was collected from in-depth interviews with expert, including owners, consultants and contractors. The results were classified and compared with each other through descriptive and pattern analyses using the NVIVO Software. As determining constructability of a project needs experience and expertise, lack of constructability can be due to late or improper decision making in planning and design. The outcome of this study shows that `IPD implementation facilitates such harmony and coordination. The case is from Tehran of Iran. Given the geographical restriction of this case study that was in Iran, there were not adequate experts in the field of IPD. Currently, in Iran, these concepts are just implemented in large projects. This study uses IPD as the most recent contractual delivery approach to facilitate easier constructability implementation in the construction industry. Having coordination between construction and pre-construction stages is very significant to reduce duplications and improve real implementation of designs.

There are numerous studies on design documentation variables without efforts to evaluate their level of importance. Therefore, the aim of this study is to evaluate the significance of these variables towards improving design documentation quality. A questionnaire survey to identify the significance of key quality variables was carried out. A total of 139 variables on design documentation quality were used. The mean score and Standard deviation of each factor were used to determine the level of significance. Based on responses from 112 construction industry players, the significance of each variable is determined. Design documentation is fit for purpose was considered highly important as an attribute while Inadequate and Insufficient documentation was ranked highest for quality influential factors. The findings will provide valuable data to stakeholders, researchers, and academics and will help enhance project performance because professionals will be aware of key factors that can influence design documentation quality. It will also aid in providing solution to sustainable infrastructure design and delivery challenges in the industry. The study offers a pragmatic data and empirical evidence to expand knowledge on design documentation quality. It is the first of its kind that explored the significance of design documentation quality variables based on the outcome of a meta-synthesis.