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CONSTRUCTION DELAY COMPUTATION METHOD

KING FAHAD UNIVERSITY OF PETROLEUM AND MINERALS CONSTRUCTION ENGINEERING & MANAGEMENT DEPARTMENT CEM 510 **********. CONSTRUCTION DELAY COMPUTATION METHOD BY Jonathan Jingsheng Shi, Member , ASCE, S.O. Cheung and David Arditi, Member, ASCE REF:

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CONSTRUCTION DELAY COMPUTATION METHOD

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  1. KING FAHAD UNIVERSITY OF PETROLEUM AND MINERALSCONSTRUCTION ENGINEERING & MANAGEMENT DEPARTMENTCEM 510********** CONSTRUCTION DELAY COMPUTATION METHOD BY Jonathan Jingsheng Shi, Member , ASCE, S.O. Cheung and David Arditi, Member, ASCE REF: JOURNAL OF CONSTRUCTION ENGINEERING AND MANAGEMENT – JAN/FEB,2001 VOL. 127 NO.1 FEB28,2006

  2. OBJECTIVE:This paper presents a method for computing activity delays and assessing their contribution to project delay. The method consists of a set of equations, which can be easily coded into a computer program that allows speedy access to project delay information and activity contributions. BACKGROUND: • Most problem in construction is delay • Construction contract = contract duration ( specified period of time) = contractor must comply to achieve substantial completion within this time • For unexpected reasons contractor fails to complete the project within the contract period • Owner will claim liquidated damages and obtain contractual release extension of time • Delay analysis based on responsibilities : delay excusable (compensable & noncompensable ) and inexcusable • Project delay result from computing activity delay • Delay computation related to as-planned schedule contrasts as-built schedule • Traditional delay analysis method based always on CPM analysis on other words any delay on critical path delay the project completion • This method is not based on CPM and no need for updating CPM • Criticality of individual activities change from day to day due to delays & accelerations which means if delay happen then extra effort from manager to up date the as-planned schedule with daily as-built information

  3. APPROACH AS: • Examine the occurrence of delay • Method for computing activity delays • Method for computing the contribution of activity delays to project delay • example

  4. Activity completion delay to reasons: Delay in the start of the activity Delay in the precedence activities Delay in the start of the activity itself for some reason Extend the duration of the activity Occurrence of Construction delay Delay precedence Late design information Delay deliveries Succeeding Not delayed Project Not delayed No resources Delay start Succeed- ing delayed Activity delay Project delayed Bad weather Extended activity duration Mang. decision Change Site condition Change scope Less resources

  5. Activity Variation • VS=actual start time – planned start time …………………....….1 • VF=actual finish time – planned finish time…………………....…2 • VD=actual duration – planned duration ……........................3 From CPM network following relationship • Actual finish time=actual start time +actual duration …….…..4 • Planned finish time=planned start time +planned duration….5 By subtract 4-5 then Eq 2 can be written as: • VF = VS + VD ……………………………………………………….…..…6 • VSP= could start time – planned start time ………………….. 7 • VSS= actual start time – could start time …………………….. 8 • VS = VSP + VSS ……………………………………….…… 9 By applying the 9 into 6 then: • VF = VSP + VSS + VD ………. 10 Accelerate VA=VSS+VD extra time

  6. Contribution of Activity Variation to Project delay • VP = actual completion time - planned completion time (+ ve 0r – ve ) • Two factors: • PDAC =MEASURING THE PROJECT DELAY DUE TO ACCUMULATED ACTIVITY VARIATIONS CONTRIBUTED BY THIS AND ALL ITS PRECEDING ACTIVITIES • PDA = MEASURING THE PROJECT DELAY CONTRIBUTED ONLY BY THIS ACTIVITY • Project delay is realized on the terminal activities ……..mechanism start from terminals and continue backward through intermediate activities • Terminal activities : are the last activities that do not have succeedings • Variation in the completion time of the terminals may contribute to project delay • PDAC= actual finish time of the terminals - planned project finish time • PDA = min ( VA , PDAC ) • Intermediate activities : those succeeding the terminals i j

  7. Example Discussion

  8. Conclusion • This paper presents a method for computing activity delays and assessing their contribution to project delay. The method consists of a set of equations, which can be easily coded into a computer program that allows speedy access to project delay information and activity contributions. • This method applicable to any intermediate construction stage for evaluating in-progress project delay • Traditional delay analysis method based always on CPM analysis require frequent updates of the as-built and as-planned schedules in order to keep track of the critical paths that may change daily. Such updating will require tremendous effort for site management. This method depend on as-planned schedule as basis of comparison for evaluating the variation in the project duration does not need to be updated. • This method is based on the finish-to-start relationship which is most common but not applicable to start-to-start or finish-to-finish relationships in current form , but equations can be expanded to these relationship as necessary.

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