when we start a project , one of the major requirement is to agree with the consultant the relation between activities , or methodology of how activities will be linked together in each field ( engineering, procurements , construction... ect), always all planners care about how to draw the relation , and not how this relation will feed me back during the stages of updating.<?xml:namespace prefix = o />
for example let us to study the relation between submission and approval for the engineering Items, of Corse first condition which control this relation is the agreed time of approval from the client which is mentioned in the general condition of contract , but how the relation will be :
Start to start with lag ( ex 30 day for time approval) or
Finish to start with negative lag or
Finish to finish with lag..
for the first wile it seems that the relation start to start with lag for the overlapped activities most accepted, because it’s give the owner the actual satiation in simple way, but this relation is not useful when the project is in delay and the contractor want to gain a progress in the engineering activities in order to recover the delay, because :
Whatever the contractor gain a progress in this activity ,this progress will not recover part of the delay. why?
because you use the relation start to start , which meen that activity of approval will start after activity of submission by 30 day , so if the contractor started to submit late, this will shift also the planned start of approval , and if the contractor start to recover this delay for this activity(submission) he will speed up the progress of submission on order to increase the percentage of progress in this activity( submission) , but unfortunately ,this will not affect the delay of the approval activity(means that planned start date and finish date of the approval activities will not shifted to be earlier) according to the progress gained .
from the above example, i want to highlight that when you use the relation start to start and finish to finish more in the program of work (base line) its will tying the activities and it will be difficult to you to recover the delay by speeding up the progress, because the progress (in the same actives) will not affect in delay when you have series of activities linked together by relation start to start, only you have one option which you can use to recover the delay, is to start the activity early more than planned or to finish the activity early more than planned, so the actual start dated and actual finish dates are controlling the delay only .
The best solution in order to have a good link between the over lapped activities is to link it by relation F.S with negative lag, this will give good results and will reflect on covering the delay when contractor have a progress in the submission. By explaining to the owner he will accept that for sure.
take care about the opinion of people regarding the negative lag , don’t believe when someone say that it’s not good,.