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Total Float take into account different calendars

6 replies [Last post]
daniel morais
User offline. Last seen 1 week 8 hours ago. Offline
Joined: 2 May 2018
Posts: 64

Hi friends,

Today I did a simple testing take into account 3 activities and different calendars A (5WD) and B (7WD) and I had two different answers but, my question is, considering the CPM schedule we are limited to found a correct critical path according the calendar? What exactly happened?

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calendar_x_criticalpath.jpg

Link file

https://we.tl/t-YVwrZDKvlf

Best Regards,

Daniel Morais

  

Replies

daniel morais
User offline. Last seen 1 week 8 hours ago. Offline
Joined: 2 May 2018
Posts: 64

Hi Alex,

Thank you for your answer.

The problem that I face everyday is exactley this, the schedule always have have FS, SS and FF activities , many calendars, many constraints and resources loaded and leveled, so, how to find the critical path that represent the backbone of the schedule as far as the timeframe is concerned? This is always a difficult because our clients, always request the critical path schedule.

Best Regards,

Daniel

daniel morais
User offline. Last seen 1 week 8 hours ago. Offline
Joined: 2 May 2018
Posts: 64

Mr. Vladimir,

Thank you for the explanation, understood.

Best Regards,

Daniel

Alex Lyaschenko
User offline. Last seen 4 weeks 19 hours ago. Offline
Joined: 15 Aug 2011
Posts: 59
Groups: None

Daniel,

There is no commonly agreed definition of Critical path :) Different PM standards, books and Systems have different interpretations. When a schedule only has FS activities, one calendar, no constraints, no resources, there is no difference in calculation. When they are presented, you can see anomalies.  

It is particularly true about a way Total Float is calculated.  

Generally, there are two main methods: 

- Activities with TF =0 

- Longest path 

You just find an example to demonstrate both methods. It is widely accepted that the Longest Path is a better way to control Critical activities.  

Regards,

Alex Lyaschenko

Daniel,

This is not workaround.

Setting 2 days total float as the condition for selecting activities that are considered as critical you include in the critical path those activities which delays can delay project finish. In case when an activiy with 7WD calendar has 5WD successor and finishes on Friday evenig it has two days total float. But if 7WD activity finishes on Monday its total float is zero though succeeding activity has different calendar. With some delay of preceding activities it can get some float that is less of two days remaining on the same path, with another delay its float can remain zero.

Critical Path shows activities that require most attention because their delays can delay project completion. These activities belong to the Critical Path even though in some moments during project execution they can have positive floats.

daniel morais
User offline. Last seen 1 week 8 hours ago. Offline
Joined: 2 May 2018
Posts: 64

Mr. Vladimir, thank you for your quickly answer.

Regarding the change concerning 16hours, in transforming the actvities in critical, this would not change in the classic CPM concept? I mean, if my schedule suffered some audit of some expert or be on a disput, he would be refused?

This would be a workaround?

Best Regards,

Daniel Morais

Daniel,

you changed the calendar of the last activity in this schedule from 7d/w to 5 d/w.

In the initial schedule its start was planned on Saturday but as the result of changing activity work week it was moved on Monday.

Preceding activities have 7d/w calendars and as the result they got two days total float, Now the preceding activity can finish on Sunday without delaying succeeding activity.

You can define what activities will be considered as critical in the current project in the project properties.

In particular, you can set that an activity will be considered as critical if its total float is less than 16 work hours.

In this case your critical path will not change.

Best Regards,

Vladimir