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Variation order cause | Number of occurrence | Percentage variation | Questionnaire | Literature review |
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Poor estimation | 1 | 3 | 1 | — |
Poor investigation | 2 | 1 | 4 | — |
Unforeseen site conditions | 3 | 4 | 2 | 8 |
Change in design by consultant/design changes | 4 | 5 | 11 | 5 |
Additional preliminaries due to time extension | 5 | 2 | 24 | — |
Client-initiated variations | 6 | 10 | 5 | 1 |
Other organizations | 7 | 13 | 20 | — |
Errors and omissions in design | 8 | 11 | 12 | 3 |
Inadequate scope of work for contractor | 9 | 14 | 10 | — |
Inadequate planning | 10 | 12 | 15 | 7 |
Local residents | 11 | 9 | 17 | — |
Substitution of materials or procedures | 12 | 15 | 28 | 2 |
Shortage of materials | 13 | 6 | 19 | — |
Conflicts between contract documents | 14 | 7 | 30 | 6 |
Technology change | 15 | 8 | 33 | 13 |
Safety considerations | 16 | 18 | 32 | 12 |
Unavailability of skills (shortage of skilled manpower) | 17 | 16 | 29 | 16 |
Defective workmanship | 18 | 21 | 26 | 18 |
Unrealistic contract durations imposed by client | 19 | 22 | 8 | — |
Lack of contractor/subcontractor experience | 20 | 20 | 14 | — |
Lack of communication between client, consultant, and contractor | 21 | 19 | 25 | 7 |
Change in economic conditions/government regulations | 22 | 17 | 9 | 19 |
Political pressure | 23 | 23 | 3 | — |
Owner’s financial problems | — | — | 5 | 4 |
The objective of the project is not well defined | — | — | 10 | 14 |
The scope of work for the contractor is not well defined | — | — | 7 | 9 |
Value engineering | — | — | 31 | 12 |
Contractor’s desire to improve his financial situation | — | — | 18 | 10 |
The contractor's financial difficulties | — | — | 23 | 11 |
Weather conditions | — | — | 13 | 17 |
Natural disasters | — | — | 6 | — |
Delay in approval | — | — | 16 | — |
Consultant's lack of judgment and experience | — | — | 21 | — |
Workmanship or material not meeting requirement of specifications | — | — | 22 | 15 |
The required tools and equipment are not available | — | — | 27 | 18 |
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