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Lead and Lag

10 replies [Last post]
Sat, 2010-01-16 13:53
Aryan Yap
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Hi All,

What is the difference between Lead & Lag?

I read in PMBOK the meaning of Lead & Lag:

1. A lead allows an acceleration of the successor activity.
2. A Lag directs a delay in the successor activity.

Can somebody explain in detail and give me an example please?

Thank you and Best Regards,

Aryan


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Replies

Mon, 2010-01-18 11:50
#1
Rafael Davila
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In order to know which task is driving you do not need to create dummy activities your software should provide you with the information on what links are driving.

Driving Links

You can replace you lags with activities if you want to avoid some of the traps when using lags but if you are still using relationships other than FS even with no lag there is still the possibility of falling into a trap, you are not 100% safe. When in need to use these remember to be very cautious as not to fall in any trap.

Keep in mind that whenever you substitute a relationship by an activity now it will not be automatically used in progress computations hence you will have to report progress on it, otherwise updating errors will offset the benefits, if any.
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Mon, 2010-01-18 06:12
#2
Aryan Yap
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Hi Mike,

Yes, what I am trying to perform now is to change the lead & lags with a certain task. In this case, I can easily determine which tasks delayed the other task.

Thank you & Best Regards,

Aryan
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Mon, 2010-01-18 06:00
#3
Mike Testro
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Hi Aryan

Samer gave the following example for a lead link

Concreting + Lag (curing period) then Deshuttering starts.

Remember that a FS link takes the calendar of the predecessor.

Concrete sets 24/7 so you will get an inaccurate result.

Best to avoid Lead Lags altogether.

Best regards

Mike Testro
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Mon, 2010-01-18 05:21
#4
Aryan Yap
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I thank you all guys for the support.

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Sun, 2010-01-17 02:38
#5
Shah. HB
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Thanks rafel for the links
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Sun, 2010-01-17 02:38
#6
Shah. HB
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hi

for further info you could check the links given by Rafel in that there are further hyperlinks hope it would worthily to you
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Sun, 2010-01-17 02:33
#7
Aryan Yap
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Hi Guys,

Thank you so much for your support. Now, I understood what’s the difference between these two.

In my understanding, all activities linked to one another that overlaps is called the LEAD. Correct me if I am wrong.

Thank you and Best Regards,

Aryan
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Sat, 2010-01-16 23:25
#8
Rafael Davila
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http://www.mosaicprojects.com.au/PDF/Links_Lags_Ladders.pdf
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Sat, 2010-01-16 17:15
#9
Samer Zawaydeh
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Dear Aryan,

The simplest example for a Lag is the deshuttering of concrete. You have to wait for the concrete curing period until the activity of deshuttering starts.

Concreting + Lag (curing period) then Deshuttering starts.

The LEAD is usually used with start to start activities; the start of the excavation activity would lead the start of the shuttering activity by a day.

It is best that you avoid the use of these LEAD and LAG in your schedule at this time, and you can use then later on when you have more complicated requirements.

With kind regards,

Samer
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Sat, 2010-01-16 14:08
#10
Shah. HB
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hi
Check this sample

http://www.warnercon.com/articles/Article%2010%20-%20Types%20of%20Lags.pdf

http://www.mckinnonsc.vic.edu.au/vceit/ganttpert/projmanterms.htm
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