Number of researches and articles have been studied on causes of delay in construction industry. The outcome of these studies have been reviewed for this particular research. Distributed the delay causes into various causing groups (consultant, owner, contractor, labor, material, equipment, project and external related groups), and the major causes of delay were rated into very high, high, medium, low and very low delay related causes. Mohamed and Tarek et al 01.
The delay factors was divided into three main groups.
1-The input factors group: was described as resources required for the project as labour, material, equipment.
2-The internal environment group: the participants in the project including-employers, consultants and contractors.
3-The unpredictable factors group: climate changes, changing in the policy of government and other casual occasions. Michal and Angieszka et al 03.
The main delay causing factors was divided into nine causing factors (contractor related, lake of labour, external factors, material deficiency, design errors, owner related, technology restrictions, consultant related and project related). Out of these delay causes or factors the technology restrictions factor was the most important and causative factor of delay. Samad and Mohamed et al 09. Eighty three factors of delay were found, and also the factors were combined into nine groups, the importance index was used to rank and rate important causes or factors of delay, and also the top ten major delay causes in Afghanistan were gathered as follows (security, corruption, unexperienced contractor technical staff, poor site management, poor supervision by the contractor, ineffectual planning and scheduling by the contractor, delay in the invoices of project by the employer or government, difficulties in project financing by the contractor and the final one type of project bidding or award). Ghulam and Kassim et al 04. Found that the Indonesian construction industry is not influenced only by labor related aspects, but there are some more significant factors (equipment, material, construction methods, site management and non-professional management), the delay causes were categorized into six different groups (people, non-professional management, design and documentation, material, execution and external factors. Keith et al 05. The most significant effects of delay were discussed (time overrun, cost overrun, litigation, disputes, lawsuits, project abandonment, bankruptcy, arbitrations. And a theoretical outline of delay factors were determined as follows (client/sponsor/owners/projects team, consultants/design engineers/contractors/sub-contractors, materials, government authorities, socio-economic aspects and others). Ghais et al 06. From this particular study gathered the delay in honouring payment certificate was the most causative and important factor of delay in construction projects by the contractor, and also this study showed that the most significant factors of delay are (time overrun, cost overrun, loss of reputation, loss of productivity, efficiency, rescheduling of the project and claim and litigation). Benjamin et al 07. It was found that (inflation, inadequate financing by the owner, poor feasibility study of the project and extreme scope changes are the key delay factors in construction projects at Middle East, and analyzed that the inadequate financing occurs due to inflation and most of the times due to poor feasibility study. The risk factors in civil engineering projects in Middle East were determined as follows (oil price instability, currency rate instability, geo-political issues and risks, labor non-availability, form of contract, non-accurate cost estimations, inflation and delay factors or causes related scope changes). Maryam et al 10. At least 42 delay causes were found and existing in a questionnaire survey. 179 experts was given their response and was analyzed by Importance Index, Spearman’s Rank Correlation, T-Test, Risk Mapping and factor Analysis. And the most major delay factor in was the low productivity of works (57.86%). The study analysis indicated that the most causing delay factors or causes in Qatar construction industry were (low productivity of worker, delay in decision making, delays related to sub-contractors, changes in project by owner and unqualified workforce. And the delay causes for the rest of the word were also given as follows (delay in decision making by the owner, low productivity of the workers, poor site management, delays related to sub-contractors works and complications in planning and scheduling by contractor. Mahanad et al 11. The delay was defined as surpassing the completion of construction project by the time duration specified in the contract, or surpassing the time duration on which both the parties agreed to the delivery of the particular project. In Indian construction industry mostly delays occurs due to poor cooperation of the participants (owner, contractor, consultant and others). The eight delay factors were found with their eight effects.
8 delay factors: owner, contractor, designer, worker, material, equipment, construction and external factors.
8 delay effects: time overrun, cost overrun, loss of productivity of owner, damage to the reputation of the company, delay in payment by owner, the participants of the project are in disputes, exit of the project, reduction in the market value. Mr.Karthik et al 12.