thanks all for your comments, and sorry Stephen for hijacking your thread, actually i am not a football fan(Please Americans it is not this silly word soccer;)
but i respect it at least for the fact that people from the other side of the ocean now know there is a country call it Algeria, which for me is a huge success.
and please moderator for the sake of fun, can you move those threads, to trivia area of the forum, perhaps you can call it, Rafael vs Mike, the revenge ;)
have a good day
Mimoune
Member for
21 years 8 months
Member for21 years8 months
Submitted by Rafael Davila on Tue, 2010-06-22 08:16
I am not really a soccer fan; I am not following the games but just wanted to add some spice into the issue. Is my way to let Mimoune know I welcome his comments about the games as he is sharing his passion for a game many love in the same way I love baseball, boxing and basketball. I do the same with our Pilipino friends who in a similar way love boxing, I enjoy their comments same as yours. Thanks for keeping the humor.
Best regards,
Rafael
Member for
20 years 7 months
Member for20 years7 months
Submitted by Stephen Devaux on Tue, 2010-06-22 08:04
i just notice this thread, i hope you enjoyed the game ;), you have to see the reaction of the English heavy lift supervisor who works with us after the game.
best regards
Mimoune
sorry, i could not resist ;)
Member for
21 years 8 months
Member for21 years8 months
Submitted by Rafael Davila on Fri, 2010-06-18 16:49
Of course paying the LDs is an option, but you got to compare it to your other options, even those I missed to mention many like second shifts, help from other contractors and many others, that is why I said there is no magic bullet, DRAG is more like a silver bullet for crashing, will keep away the wolf-man but not a vampire.
I already ruled out other options when I said “when everything else makes no sense”, just to force you into the idea of crashing and at this point not be distracted by the other options.
Hope you are enjoying the games, same as I did with the NBA Finals except last night game. A Yankee/Mets fan which happens to be a Celtics fan, how about that? Fenway franks is the only good thing at The Wall.
"If you can forecast where these circumstances are most likely to arise then I can see the pro-active advantage."
Ill gratefully accept that -- I think its the best Im likely to get. Big Grin
Raphael wrote:
"Drag tells you up to how much the actual critical path can be compressed and prevents over compressing activities when some portion does not further reduce total duration. Then perhaps no further reduction should be done on these activities but in others along the multiple critical paths."
The word "perhaps" is key. However, the optimization process can also be iterative -- if you compress a 30D task that has drag of 12D to a new duration of just 10D, now the activity has TF of 8D, and the parallel CP activity may have drag of 8D. Now you can look to gain even more time by compressing that activity, etc.
But, with "perhaps", I take your point.
Raphael also wrote:
"Crashing after first critical path is compressed gets complicated, DRAG helps. Is not a magic bullet but good to have in your bag of tricks."
Well put. There is no magic bullet in PM -- just metrics and wisdom.
Mike also wrote:
"When I read the phrase "multiple critical paths" I reach for my fiddle detector."
Me, too! Ive seen em, but Im always suspicious!
But Raphaels most recent post is right on the money, in terms of understanding the implications of drag and crashing.
Fraternally in project management,
Steve the Bajan
Member for
21 years 8 months
Member for21 years8 months
Submitted by Rafael Davila on Fri, 2010-06-18 16:08
When you construct a schedule there is probability 99.99999% there will be a single critical path. But when your job is in trouble, after no more changes in logic or normal increase in resource availability make sense you have no option than to crash your activities. Is a procedure of last resort and you better do it economically as you already are in trouble.
You only crash activities that impact project duration; these are activities on your longest path. Why spend money into crashing activity time that has no impact on total project duration? It will not only be a waste of money but will distract your resources into futile exercise, this might even create more chaos.
After some reduction of your critical activities duration or crashing (reduction in duration to its practical limit) then a new parallel critical path will emerge unless you want to create for fun float where not needed.
Under FS only schedules and no resource leveling and no constraints DRAG is a beauty. Under resource leveling it gets complicated but it still helps much. Its use is augmented in the case youe CPM has many paths that can potentially become critical, paths with low float amount. Drag tells you up to how much the actual critical path can be compressed and prevents over compressing activities when some portion does not further reduce total duration. Then perhaps no further reduction should be done on these activities but in others along the multiple critical paths.
Crashing after first critical path is compressed gets complicated, DRAG helps. Is not a magic bullet but good to have in your bag of tricks.
Its true I paddle about in the simple Construction Pond where FS Links and no constraints are best practice.
It is relatively easy to spot potential bottlenecks because I know where they happen and can schedule around them - scaffolding to a high level gable going through a low level roof is a typical example.
Even so a typical housing project could have as many as 10k tasks to control but it is relatively simple (but boring) when a routine is set up.
No I dont have a new algorithm - I wouldnt know what one was even if it crept up and bit my bum - I am at the level where I dont need to know how to design a ball point pen in order to write a letter.
Of course if you are planning for something that has never been done before then most of the schedule is going to be pure guess work anyway so later improvements is a big advantage.
Even so the starting point must be the critical path and if circumstances create a new critical path then that has to be reviewed as and when it happens.
If you can forecast where these circumstances are most likely to arise then I can see the pro-active advantage.
Meanwhile Ill stick to my pond.
Best regards
Mike Testro
Member for
20 years 7 months
Member for20 years7 months
Submitted by Stephen Devaux on Fri, 2010-06-18 11:03
I cant say for certain, because Im not sure I understand your filtering process -- but I honestly cant see how what you describe would compute how much time each activity is adding to the duration, even in a short network.
On a small network with only FS relationships, DRAG is pretty easy to compute visually. On a large network with complex dependencies, its both difficult and very time-consuming without software help. (As a consultant, Ive spent much time helping clients identify opportunities to recover schedules by papering my house with network diagrams. Without software, it would sometimes take more than a day to compute the DRAG in a 3000+ activity network.)
Knowing how much time each activity/bottleneck/constraint is adding to the project duration seems like a pretty fundamental metric -- more so than float (total or free), which pretty much every package computes, yet is off the critical path. You can have a thirty-day activity on the CP thats only adding one day, but an eight-day activity thats adding eight. But yet the metric, and even the idea of it, is not listed in the PMBOK Guide nor any other PM book I know of, and no software computed it prior to my book. It certainly was new info to both Vladimir Liberzon of Spider Project (you can ask him) and Joel Koppelman (founder and CEO of Primavera), enough so that Vladimir programmed an algorithm to do the computation in Spider.
So if you have a filter and simple algorithm that will compute it, Id love it if you could send it to me.
"But what is the purpose - the critical tasks will be as tight as they possibly can be to start with."
Clearly, the projects you work on are very different from mine. Maybe what you describe is the norm on the construction projects you work on. Ive done a little construction and that certainly hasnt been my experience, but I wont deny perhaps its been yours.
However, Ive also worked with many other industries, and I can assure you that such is not the case in aerospace/defense, or nuke plant shutdowns, or pharma, or consumer electronics (and I wont even mention information systems!). Before optimization of the schedule, its not unusual to have activities with hundreds of days of float, or four or more weeks of DRAG, on a two year project. Typically, I find that I can compress a schedule anywhere from 10% to 40%, and DRAG computation is what makes it possible.
Id also add that even if "the critical tasks will be as tight as they possibly can be to start with", that may be how they start -- but its not how theyll be when things start slipping! The the typical scheduler is scrambling to find places to recover, and the DRAG metric points him to productive areas.
Member for
19 years 10 monthsRE: Trial version of DRAG-computing software
Hi Mimoune
I can’t move individual threads - just the whole topic.
Its not the first time a topic has gone wildly off course and lets hope it won’t be the last - thats one of the joys of PP.
By the way - soccer is an acceptable English word for a game that should really be called feetball.
Best regards
Mike Testro.
Member for
19 yearsRE: Trial version of DRAG-computing software
hi all
thanks all for your comments, and sorry Stephen for hijacking your thread, actually i am not a football fan(Please Americans it is not this silly word soccer;)
but i respect it at least for the fact that people from the other side of the ocean now know there is a country call it Algeria, which for me is a huge success.
and please moderator for the sake of fun, can you move those threads, to trivia area of the forum, perhaps you can call it, Rafael vs Mike, the revenge ;)
have a good day
Mimoune
Member for
21 years 8 monthsRE: Trial version of DRAG-computing software
Mike and Stephen,
I am not really a soccer fan; I am not following the games but just wanted to add some spice into the issue. Is my way to let Mimoune know I welcome his comments about the games as he is sharing his passion for a game many love in the same way I love baseball, boxing and basketball. I do the same with our Pilipino friends who in a similar way love boxing, I enjoy their comments same as yours. Thanks for keeping the humor.
Best regards,
Rafael
Member for
20 years 7 monthsRE: Trial version of DRAG-computing software
"But then England beat Australia 21 - 20 in the game that really matters over the weekend."
Wow! Thats a really low scoring cricket match!
Fraternally in cricket,
Steve the Bajan
Member for
19 years 10 monthsRE: Trial version of DRAG-computing software
Hi Rafael.
It could easily happen - we will know tomorrow.
But then England beat Australia 21 - 20 in the game that really matters over the weekend.
Best regards
Mike Testro
Member for
21 years 8 monthsRE: Trial version of DRAG-computing software
Member for
19 years 10 monthsRE: Trial version of DRAG-computing software
Hi Mimoune
It could be that England is out of the contest - but at least France will be on the plane first.
Algeria played well and deserve to go through.
Best regards
Mike Testro
Member for
19 yearsRE: Trial version of DRAG-computing software
hi Mike
i just notice this thread, i hope you enjoyed the game ;), you have to see the reaction of the English heavy lift supervisor who works with us after the game.
best regards
Mimoune
sorry, i could not resist ;)
Member for
21 years 8 monthsRE: Trial version of DRAG-computing software
Mike,
Of course paying the LDs is an option, but you got to compare it to your other options, even those I missed to mention many like second shifts, help from other contractors and many others, that is why I said there is no magic bullet, DRAG is more like a silver bullet for crashing, will keep away the wolf-man but not a vampire.
I already ruled out other options when I said “when everything else makes no sense”, just to force you into the idea of crashing and at this point not be distracted by the other options.
Hope you are enjoying the games, same as I did with the NBA Finals except last night game. A Yankee/Mets fan which happens to be a Celtics fan, how about that? Fenway franks is the only good thing at The Wall.
Best Regards,
Rafael
Member for
19 years 10 monthsRE: Trial version of DRAG-computing software
Hi Rafael
You wrote - ".... you have no option than to crash your activities."
There is always the option to face the over run and pay the LAD’s - particularly if the cost of acceleration is more costly and the outcome doubtful.
There is always the chance that the employer will give you a chance for an EoT to fudge the issue.
Best regards - its half time with England v Algeria - must dash.
Mike Testro
Member for
20 years 7 monthsRE: Trial version of DRAG-computing software
Mike wrote:
"If you can forecast where these circumstances are most likely to arise then I can see the pro-active advantage."
Ill gratefully accept that -- I think its the best Im likely to get. Big Grin
Raphael wrote:
"Drag tells you up to how much the actual critical path can be compressed and prevents over compressing activities when some portion does not further reduce total duration. Then perhaps no further reduction should be done on these activities but in others along the multiple critical paths."
The word "perhaps" is key. However, the optimization process can also be iterative -- if you compress a 30D task that has drag of 12D to a new duration of just 10D, now the activity has TF of 8D, and the parallel CP activity may have drag of 8D. Now you can look to gain even more time by compressing that activity, etc.
But, with "perhaps", I take your point.
Raphael also wrote:
"Crashing after first critical path is compressed gets complicated, DRAG helps. Is not a magic bullet but good to have in your bag of tricks."
Well put. There is no magic bullet in PM -- just metrics and wisdom.
Mike also wrote:
"When I read the phrase "multiple critical paths" I reach for my fiddle detector."
Me, too! Ive seen em, but Im always suspicious!
But Raphaels most recent post is right on the money, in terms of understanding the implications of drag and crashing.
Fraternally in project management,
Steve the Bajan
Member for
21 years 8 monthsRE: Trial version of DRAG-computing software
Mike,
When you construct a schedule there is probability 99.99999% there will be a single critical path. But when your job is in trouble, after no more changes in logic or normal increase in resource availability make sense you have no option than to crash your activities. Is a procedure of last resort and you better do it economically as you already are in trouble.
You only crash activities that impact project duration; these are activities on your longest path. Why spend money into crashing activity time that has no impact on total project duration? It will not only be a waste of money but will distract your resources into futile exercise, this might even create more chaos.
After some reduction of your critical activities duration or crashing (reduction in duration to its practical limit) then a new parallel critical path will emerge unless you want to create for fun float where not needed.
Best Regards,
Rafael
Member for
19 years 10 monthsRE: Trial version of DRAG-computing software
Hi Rafael
When I read the phrase "multiple critical paths" I reach for my fiddle detector.
I have never yet encountered more than one critical path that runs through a properly constructed programme that hasnt been created artificially.
Best regards
Mike Testro
Member for
21 years 8 monthsRE: Trial version of DRAG-computing software
Mike,
Under FS only schedules and no resource leveling and no constraints DRAG is a beauty. Under resource leveling it gets complicated but it still helps much. Its use is augmented in the case youe CPM has many paths that can potentially become critical, paths with low float amount. Drag tells you up to how much the actual critical path can be compressed and prevents over compressing activities when some portion does not further reduce total duration. Then perhaps no further reduction should be done on these activities but in others along the multiple critical paths.
Crashing after first critical path is compressed gets complicated, DRAG helps. Is not a magic bullet but good to have in your bag of tricks.
Best Regards,
Rafael
Member for
19 years 10 monthsRE: Trial version of DRAG-computing software
Hi Stephen
Its true I paddle about in the simple Construction Pond where FS Links and no constraints are best practice.
It is relatively easy to spot potential bottlenecks because I know where they happen and can schedule around them - scaffolding to a high level gable going through a low level roof is a typical example.
Even so a typical housing project could have as many as 10k tasks to control but it is relatively simple (but boring) when a routine is set up.
No I dont have a new algorithm - I wouldnt know what one was even if it crept up and bit my bum - I am at the level where I dont need to know how to design a ball point pen in order to write a letter.
Of course if you are planning for something that has never been done before then most of the schedule is going to be pure guess work anyway so later improvements is a big advantage.
Even so the starting point must be the critical path and if circumstances create a new critical path then that has to be reviewed as and when it happens.
If you can forecast where these circumstances are most likely to arise then I can see the pro-active advantage.
Meanwhile Ill stick to my pond.
Best regards
Mike Testro
Member for
20 years 7 monthsRE: Trial version of DRAG-computing software
Hi, Mike.
I cant say for certain, because Im not sure I understand your filtering process -- but I honestly cant see how what you describe would compute how much time each activity is adding to the duration, even in a short network.
On a small network with only FS relationships, DRAG is pretty easy to compute visually. On a large network with complex dependencies, its both difficult and very time-consuming without software help. (As a consultant, Ive spent much time helping clients identify opportunities to recover schedules by papering my house with network diagrams. Without software, it would sometimes take more than a day to compute the DRAG in a 3000+ activity network.)
Knowing how much time each activity/bottleneck/constraint is adding to the project duration seems like a pretty fundamental metric -- more so than float (total or free), which pretty much every package computes, yet is off the critical path. You can have a thirty-day activity on the CP thats only adding one day, but an eight-day activity thats adding eight. But yet the metric, and even the idea of it, is not listed in the PMBOK Guide nor any other PM book I know of, and no software computed it prior to my book. It certainly was new info to both Vladimir Liberzon of Spider Project (you can ask him) and Joel Koppelman (founder and CEO of Primavera), enough so that Vladimir programmed an algorithm to do the computation in Spider.
So if you have a filter and simple algorithm that will compute it, Id love it if you could send it to me.
"But what is the purpose - the critical tasks will be as tight as they possibly can be to start with."
Clearly, the projects you work on are very different from mine. Maybe what you describe is the norm on the construction projects you work on. Ive done a little construction and that certainly hasnt been my experience, but I wont deny perhaps its been yours.
However, Ive also worked with many other industries, and I can assure you that such is not the case in aerospace/defense, or nuke plant shutdowns, or pharma, or consumer electronics (and I wont even mention information systems!). Before optimization of the schedule, its not unusual to have activities with hundreds of days of float, or four or more weeks of DRAG, on a two year project. Typically, I find that I can compress a schedule anywhere from 10% to 40%, and DRAG computation is what makes it possible.
Id also add that even if "the critical tasks will be as tight as they possibly can be to start with", that may be how they start -- but its not how theyll be when things start slipping! The the typical scheduler is scrambling to find places to recover, and the DRAG metric points him to productive areas.
Fraternally in project management,
Steve the Bajan
Member for
19 years 10 monthsRE: Trial version of DRAG-computing software
Hi Stephen
Surely you can create the same information by filtering on Non Crtical Tasks and then generating a critical path within the filter.
The difference will be the DRAG as you call it.
But what is the purpose - the critical tasks will be as tight as they possibly can be to start with.
Best regards
Mike Testro