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Delays and cost overruns are evidently frequent problems in the construction industries of many developed and developing countries. The purpose of this paper is to assess factors leading to time overruns (delays) and cost overruns in construction projects in the Gaza Strip. Since there appear to be additional special contributors to delays here, the relative perceptions of contractors, consultants and owners are compared, based on a listing of causal factors derived from previous studies elsewhere, together with other factors arising from special conditions in the Gaza Strip.

A survey of a randomly selected samples yielded responses from 66 contractors, 27 consultants, and 31 owners. The survey included 110 delay factors/causes which were grouped into 12 major groups. The same survey also included 42 cost overrun factors. The level of importance of the delays and cost overrun factors were measured and ranked by their importance indexes, according to the perspectives of contractors, consultants, and owners.

There seems to be a general agreement between contractors, consultants and owners regarding causes of delays and cost overruns. The main four causes of time delays included strikes and border closures, material‐related factors, lack of materials in markets, and delays in materials delivery to the site. Additionally, the main three causes for cost overruns included price fluctuations of construction materials, contractor delays in material and equipment delivery, and inflation.

The outcome of this paper will assist owners, contractors, and consultants in understanding the reasons for delays and cost overruns, thus eliminating or minimizing these causes. This could be achieved by better management of the projects and by finding new methods for storing the critical materials from the beginning of the project. Furthermore, the local government is advised to initiate legislation to overcome problems arising from monopolies in the supply of construction materials.

Waste is typically encountered during the building's life cycle, from the design phase, through the construction phase, to modification and demolition. Most of these construction wastes are unnoticed or unattended by project managers, which lead to serious environmental problems. Effective waste reduction strategies will require a thorough and detailed understanding of the causes of construction waste. Hence, this paper aims to explore critical waste factors (CWFs) affecting the performance of construction projects.

An extensive literature review was carried out to determine these factors based on previous studies, from which a questionnaire was developed. Series of statistical analyses such as reliability analysis, Spearman Correlation, Kruskal–Wallis and factor analysis were performed on a total of 330 valid responses to identify latent factors responsible for wastes occurrence.

This study reveals 31 CWFs through evaluation of prior relevant studies carried out in several countries and then adjusted and validated through semistructured interviews. The significant differences in views within various groups of respondents with different organizational characteristics are highlighted. The results of factor analysis showed that there are six principal components extracted with 66.3% of variance explained (material-related factors; subcontractors and workers; planning, communication and coordination; people involvement and financial issues; people development strategies; and external factors).

This study differs from other studies in the literature by gathering all relevant waste factors including those related to nonphysical waste such as time, budget, workers and equipment. Furthermore, this paper will be of great interest to both practitioners and researchers since it brings various recommendations concerning the prevention/reduction of waste through lean construction for more sustainable construction projects.

The purpose of this paper is to present a systematic review of studies on CPD published between 1985 and 2018.

Before identifying common CPD, research trends were examined in terms of the number of publications in selected journals, as well as the contributions made by countries, institutions and researchers.

The findings reveal that researchers from developing countries have contributed the most to identifying the causes of CPD. A total of 149 causes of CPD were identified in a thorough review of 97 selected studies. Weather/climate conditions, poor communication, lack of coordination and conflicts between stakeholders, ineffective or improper planning, material shortages, financial problems, payment delays, equipment/plant shortage, lack of experience/qualification/competence among project stakeholders, labour shortages and poor site management were identified as the ten most common CPDs.

Being the first study of its type, this study provides insight into the research output related to this area and identifies a common set of CPDs, which may provide a better understanding of the key areas requiring attention where steps should be taken to minimise or control factors causing delays in construction projects.