Building a Delay Fragnet

hi this is bill pappan managing partner with construction science and today we're going to look at delay fragments now the word fragment is somewhat unusual even among people who will work with Primavera and CPM schedules I often find that during our training classes but no one has ever heard of a fragment and there's actually two types of fragments that are commonly used by schedulers the first fragment involves repetitive work for example I'm going to highlight a series of activities here if I have another location where the work is very similar I could copy this quite easily in Primavera and paste it elsewhere change the activity IDs to make them unique and I might also need to change the durations or even some of the logic but the important thing is I found a way to reuse some of my logic and this is a very important trick for schedulers to save time on almost every project I'm involved with there's some amount of repetitive work might even only be a few activities but it's something I can reuse but the fragment we're going to look at today is a Trudel a fragment and fragment would mean a partial schedule just as you see here with southbound there's only a few activities here that represent the southbound work so a delay fragment can be one or just a few activities it's a subnetwork so we have the entire schedule which is the network diagram and the fragment is a sub Network so in this example we're going to look at a delay to this activity down here remove existing concrete and you'll also notice that as days of float a common misconception about delays is that the delay must be on the critical path well that's partially true we can't claim additional time unless the event that's causing the delay pushes out the project completion date but in many cases the activity that's being delayed is not currently on the critical path but it becomes critical because of the delay so in this example even with five days of float if those five days are consumed by the delay then that can become a time extension so in this example we are going to assume that this activity is being extended by seven days now a good way to do this is to make it abundantly clear to everyone that in fact we have put a fragment in the schedule my purpose here is not to confuse people and not to obfuscate what we're doing so I'm going to add a new activity and everyone has their own personal preference now in this example because I might be coming in and sorting by activity IDs later on and for those of you who are not familiar with p6 I am currently sorting by the first column so I may come in and do something like this to give it still the same prefix so that it sorts with the stage one northbound work that's what's represented by the prefix s1 in but to do something like this and I have a couple of ways of doing it I might indicate the type of delay such as an RFI by typing in those letters and something like this perhaps to indicate that it's RFI one and then here I need a description and some people it's our own personal preference might start it off with something like a capital levels or how about just saying what we mean it's the delay RFI number zero zero one so I'll do something like this again because I want everyone to be put on notice that in fact I've done something here I've added an additional activity to the schedule now by default Primavera through in five days I'm gonna make it seven days it's not currently tied to anything so how do we represent that this is seven days of additional work well one thing we want to look at is the original activity and what its successors are so I'm going to bring up the successor menu and we'll see that the activity that follows the one we're looking at on the screen is in fact this activity right here 10:15 in the same location so if I scroll back up here you can see what's right there so we want to insert our new activity between this one and its successor which is activity 10:15 so I'm going to replicate that by doing this I'm going to highlight this activity hold down my control key and I'm going to come up and select as the successor to this activity 10:15 right click link activities that takes care of successor I'm duplicating the successor that follows this activity and let's make sure we're highlighting the correct one I'm highlighting this activity because this is where we're adding seven more days and we're inserting after this activity this one and then this one is now tied to the successor of 1010 it's going into 10:15 now this activity still meets a predecessor so to add these seven days on to the end of these three days highlight this activity I'm gonna hold down the control key highlight this one right-click and we'll go to link activities again so let's take a look at this activity down here by itself and I'll have to click off that once and let's look at the logic so here's the predecessor coming in here's the successor coming out so we've managed to insert exactly seven days now one other key here is that I have restrained the end date of the project with a constraint so the very last activity project completion has a constraint in this case January 3rd 2014 this is important because I want this fragment to generate negative float negative float representing that we're behind schedule currently we're exactly on schedule so let's go back to stage 1 here's our activity and now we're going to schedule the project come up to tools schedule I'm going to keep the data date the same because there's nothing else about this that I'm changing other than the fact that we've added 7 extra days to this activity and now we see a negative 2 if we go to project completion will see that this delay carries all the way through now it will warn you that my project completion milestone is based off of a 7-day calendar all of my work activities are using a workday calendar so even though the float values are not the same these activities are in fact on the critical path together and to get another way of visualizing this I can even change the bottom layout to show this activity in a pure logic sense so let's go look at our trace logic I'll have to modify this and that's our trace logic I apologize we're going to do it this way it's a different type of lei now in some versions of Primavera the web-based versions we access this a little bit differently but now you're seeing in this box my new activity and you can see that it's clearly inserted between the original activity which had a three-day duration and the successor to that original activity now we have another type of delay and we'll just change this bottom layout for now back to details we have another type of delay where perhaps the work is being prevented from starting up so in other words it's not that we added several more days to the activity but we're not able to start on the date that we are expecting so I'm going to take out this activity and when I reschedule the project we should see everything go back to normal so let's go look at our activity up here put the five days of float and actually we need to go a little bit further here so it's this one right here and let's say we can't start it on March 6th so I want to add an activity they'll help explain why that's not possible and in this case we'll have to take advantage of a constraint or at least typically we'll do something like that so I am going to add a new activity and again might want to indicate why we're being held up maybe this time it's a change order and I might just sent that with a sea-change order one so for whatever reason we can't start right away so this activity is going to hold up the start of the one up here I'm going to hold down the control key highlight this one up here link activities now the key here when we're putting in something like this an event that's holding up the start of something else as we might very well need a constraint to indicate when was the change order issued I'm keeping it real simple here in some cases a change order might need to be represented by several activities to indicate that we initially received a proposal we had to prepare to price the proposal and there might have been discussions and so forth in terms of what we were proposing to do so in this case though I'm just going to say everything's been resolved we just have this change order it was issued on March 4th March 4th of 2013 so we need a constraint we're going to stay in the status tab and this come down to activity let's give it a constraint I usually use start on in a situation like this let's go to 2013 March and the 4th so we might have received the change or on March 4th but we're not able to start right away with the work associated with it so then I'll need a duration for this now one way we can do this we can have Primavera calculate the duration for example I might want to say that it goes from March 4th out to March 20th well how many working days is that rather than keep plugging in different numbers and testing them I might just want to take advantage of the expected finish I'll just go into this calendar jump ahead to March and pick the 20th so I'm going to use Primavera ability to calculate the duration for me knowing that we're going to start this activity on March 4th let's go ahead and schedule the project and you see March 4 xx up here you also see that March 20th is now reflected is both the expected finish date and the current finish date for that activity and you'll see ultimately the impact is that this activity is causing a 6th day delay to the project 6 working days or slightly more in calendar days in this case would be 10 calendar days but again this now has become a critical path activity and it is delaying the project so these are both good methods of representing something that's happening to a project either that the activity is going to take longer than expected because of some unforeseen event or even the start of the activity the original work is being held up by some sort of unforeseen event one last thing we might consider is adding a special activity code to represent all of this I'll go into my activity codes I'm using project specific activity codes on this project so we might do something like this add a new one that will call impacts because who knows we might have several of these events over the life of the project so now I've got impacts I close this let's select impacts and start adding some values and this is where I might give them different types of values depending on if it's an RFI impact and in fact what some people do is they might list every single RFI so it's our 5 1 RFI 2 so they can sort by all of them but I did I generally grouped them so I can say that these are RFI impacts and then I might have another category Co 4 change order impacts and so forth and then these values would be associated with those activities so we close this out highlight the activity that's additional and I go over to my codes and I assign that value I've got to come over to project codes again because that's what I'm using and they're down here because once more I'm not trying to hide this information from anyone anything I can do to make it clear what my methodology was for generating this delay to the schedule I think benefits all parties well I hope you enjoyed this presentation on delay fragments if you have any questions feel free to contact us at construction science our website is

Channel: Bill Pepoon

Views: 58,116

Rating: 4.8490567 out of 5

Keywords: Primavera P6, Construction Delays, Time Extension Request, CPM Scheduling, CPM Schedules, Primavera Schedules

Id: BzoTEy502ZU

Length: 17min 10sec (1030 seconds)

Published: Wed Nov 13 2013