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Primavera Scheduling

Are You a Pigeon?

Primavera SchedulingPigeons mystified Charles Darwin. He mentions them in the very first chapter of On the Origin of Species:

“The diversity of breeds of pigeons is truly astonishing. If one compares the English Messenger with the short-faced Culbutant, one is struck by the enormous difference of their beak, resulting in corresponding differences in the skull.”

There are as many species of pigeons as there are of dogs or cats. But today we are focusing on carrier pigeons and their cousins, homing pigeons. And what a noble history! Noah was the first to recognize a pigeon’s ability to carry a message. The Romans used pigeons to transmit the results of chariot races. Genghis Kahn and Charlemagne relied upon pigeons to carry messages to troops, as did the French in the Vietnam War.

Even today, pigeons are used to carry blood samples in remote parts of England and France. Not surprisingly, pigeons have also been dragged into nefarious duties. Drug traffickers in Afghanistan and Pakistan have utilized flocks of pigeons to deliver heroin, each one carrying 10 grams.

But let’s be honest. If rats could fly we might have used them instead. Pigeons deliver a message – right or wrong – from one party to another. They don’t (can’t) read the message or vouch for its accuracy.

Don’t be a pigeon. Too many schedulers are simply delivering information that is incorrect or incomplete. They fail to consider whether the current critical path makes sense, ignore activities that clearly should have had progress by now, and fail to analyze the potential impact of unforeseen events.

Not all information can be easily verified, of course. Unless the scheduler is posted to the field he or she can not independently verify actual dates, installed quantities, percent completes and the like. Still, there are times when the reported progress makes little sense, like my client who said he had started plumbing fixtures on the third floor of the building at a time when the structural steel to the second floor was being erected (he was taking credit for plumbing fixtures that had been delivered to the jobsite, but we had a procurement activity for that scenario).

That story involving the plumbing fixtures happened more than 25 years ago. Schedulers have long memories! More recently, I have been reviewing schedules on a 34-story apartment tower in the midwest for the owner. Ironically, plumbing is once again the issue.

A couple of months ago, installation of water heaters on nearly every floor showed up on the critical path. And with one week scheduled for installation per floor, we had water heaters occupying about seven months of the remaining critical path.

I understood how the water heaters wound up on the critical path. The contractor had added activity relationships between water heaters on each floor – something we were calling “crew restraints” way back in the early 1980s.

Here is the funny part. When I filed my report with the owner, the contractor accused me of modifying his schedule update! He had no idea these crew restraints existed or why they had been added. The reality is that the crew restraints had always been in the schedule but due to better progress on other paths, this water heater path had now been exposed.

If you are wondering why water heaters were such a concern, the fact is that most of the interior work (drywall, painting, etc.) had similar crew restraints. But only the water heaters assumed one floor at a time. I have no idea why. It is clearly a very conservative assumption, and as many of you who read my blog on a regular basis already know, I prefer The Schedule That Can be Beat.

Nevertheless, this project is behind schedule and letting the water heaters control the project completion date is not acceptable. Yet this trend continued for another month. Finally, the contractor revised the logic so that water heaters overlapped on some floors. The critical path is now starting to make a lot more sense.

That’s just it. A good scheduler should know what belongs on the critical path. Even when I am still building the baseline schedule I have an idea of what will be critical. During the monthly updates I believe I know what should be critical as well if my logic is still valid and the contractor makes sufficient progress.

Submittals tend to be ignored by the contractor because so many of them have large float values. Whenever a submittal pops up on the critical path after I make a preliminary run of the monthly update I get very suspicious. Most of the time, the contractor’s memory improves dramatically when I tell him a submittal is on the critical path (“oh yeah, we submitted those shop drawings weeks ago!”).

Schedulers cannot afford to be gullible. People gives us bad data all the time and expect a good result. Not going to happen! The guy who told me he was 75 percent complete last month will report that he is 60 percent complete this month. Which number is the truth? The reality is that we tend to get better information on the most critical activities because everyone more or less understands what “critical” means (fingers crossed).

So how do we avoid becoming pigeons? Here are a few things to consider:

  1. Never publish a schedule until the draft version has been reviewed by the project stakeholders. We do not want someone coming back and saying the logic is wrong, the durations are a fantasy, etc. after the schedule has been submitted to the owner.
  2. Use Activity Steps on complex tasks to make it easier to report progress. I think Activity Steps are one of the best features in Primavera P6 ignored by most casual users.
  3. “Gut check” the critical path. Even if the critical path seems acceptable to other project stakeholders, they are probably not scheduling experts and they certainly do not understand the details of the schedule nearly as well.
  4. Always use Retained Logic as the scheduling method in Primavera P6 for activities with progress. Nothing keeps you, and everyone else, honest like being confronted with out-of-sequence work.
  5. Avoid unnecessary logic changes. If the project is not going according to plan, why? If the owner is causing work to be performed out-of-sequence we need to preserve the logic to show the delay. But if the contractor has simply changed his mind, by all means modify the logic to keep it realistic.
  6. Educate yourself. If scheduling is not something you really understand, you need training or guidance. I studied CPM in college, but I really did not know how to apply it correctly until I started working side-by-side with professional schedulers.

There you have it. Spread your wings and fly! Okay, so perhaps that is not really the best metaphor.