How to incorporate operational interruptions ...

Billy,

I think contingency is the answer. And I think we are into the risk management area here. When we build schedule, we have to take into account "risks" that each project have to face. Like weather, equipment breakdown, site accident and the like. These risks are unforseeable events, however, it can be manage. We place contingence $ in the bid price for these risk and it will be the same to place contingence time when you build your schedule. Place additional time in each individual activity. However, you cannot place an activity call contingency in your schedule. When you build your schedule, base on these contingency and stated in your assumption statement for later use. (and usually the client contract will include some of these conditions)
For risk that we cannot manage or infulence, like terrorist attack, riot, change in government... then we just have to accept the risk in your schedule & bid price.

Alex

Thanks for Alex’s reply.

Maybe I ask in another way.

Would anyone give me some ideas on "Operational interruptions can be modeled using resource calendars or probability distributions for productive hours/day, depending on weather patterns" ?


Best regards,

Billy

I have some experiance in this We worked in a Bleach Plant with a lot of Gas/Fume Leaks. Yes not all Chemical Plants is up to standard. Due to past experiance we have calculated for every hour worked you spend half an hour out of the plant. In our calender we changed the working hours from 12 Hrs to 8 Hours to allow for this.

I hope this assist. (I have just used shorten Hours per Day)

Option two is to Increase the Activity Duration with 50 %.

But also remember to keep good record of this so if it is greater than allowed you might be able to claim. I would suggest to play open book on this. It is a high Risk Subject.

Billy,
I like, and used, the Alex approach.
You should look for any weather statistics in the region where you are working, cold day/night, rain and apply as a contingency to the affected activities or chain of activities.
You can consider these contingency in the single activities or put at the end of the chain.
In the last case if an activity is planned to happen but due to the weather condition will not, in the next update you will decrease of one unit the weather contingency.
In this way you can also monitor it closer.
We use this technique for reduced possession of the area.

Thanks for all replies.

Let’s further consider an example.

Activity Y is resource dependent and needs resources Eng1
and Eng2. And this activity needs 5 days to complete the
activity. Eng1 would not be available on day 2 & 3 and Eng2 would not be available on day 3 & 4. As a result, the original duration of the activity would change to 7 days after scheduling. The following figure would show the situation. X means holiday and both resources will work 5 days to complete the activity.

1234567
-XX---- Eng1
--XX--- Eng2

How can I get 8 days as a solution ?

12345678
-XX#---- Eng1
-#XX---- Eng2

#: Activity Y can not proceed without both Eng1 & Eng2 exist.

A better version :

......would change to 7 days after scheduling. The following figure would show the situation. X means holiday and both resources will work 5 days to complete the activity.

1234567
oXXoooo Eng1
ooXXooo Eng2

o: task working or business day.

How can I get 8 days as a solution ?

12345678
oXX#oooo Eng1
o#XXoooo Eng2

#: Activity Y can not proceed without both Eng1 & Eng2 exist.