Modeling and Optimizing Schedules with Line of Balance and Start-Finish Relationships

In this episode, Ricardo explains the benefits of using the Line of Balance with Start-to-Finish relationships, especially on projects with repetitive tasks. This podcast is based on the latest article published on his site. Read the article at http://www.ricardo-vargas.com/articles/modelling-and-optimizing-schedules-with-line-of-balance-and-start-finish-relationship/

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Episode transcript

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Hello, everyone. Welcome to the five minutes BM podcast today, like to share with you one paper. I presented that the PMI global Congress in here in London, 2015, that talks about the Start two Finish Relationships, especially with line of balance. When I have repetitive work on a project first, why decided to present a paper two work on a paper that covers this topic? Is that true? Only because almost nobody knows exactly why and how they should use.

They start to Finish Relationships we live in the world that is finished to start 99% of the people even more use Finish to start. And they do know that why tools like Microsoft product like Primavera. Why do they have this kind of strange relationship? The first thing you need to know, the relationship is a strange, because you have a wrong mindset or the wrong mindset is about predecessor and successor in your mind, predecessor chronologically first successor comes chronologically after.

So you think that the relationship between predecessor and successor is a chronological Relationships this is a big mistake because this is a valid yes. When you have finished to start a relationship and because do you use this 99% of the time, this concept can be inter and I did ask a chronological in 19. Yeah. 5% of the cases, but then when you face start to finish, then you get crazy because you can say, look, but then prey, the sash or a concept does not work anymore.

So I want to redefine the concept of predecessor and successor. Instead of thinking in a chronological link, let's think in a logical way, it doesn't matter. Predecessor is someone that must be started or a Finnish to generate durability to the success. To start a Finish can not do anything until the predecessor does something. This is Sasha is waiting for. This is a very, very important concept because this change the whole logic on how your do scale out.

And to do that, let's give you an example that I describe on the paper. So let's suppose you have building a Fort store, building floor one to three and four, and let's suppose that you have three works to do on each floor. The floors are completely denticle. You need to build waltz. This is a four day task. Then you need to paint the walls. This is a two day task, and then you need to put furniture on the floor. This is a three day task.

So each for or you have for two and three days, construction, painting and furniture. Okay. And you need to do this in a sequence ride. You can not paint. If you do not have the wall, you cannot put the furniture. If your do not have the painting. And also there is a link on the vertical, on the construction. You cannot consider the walls of the second floor without the first one. Let's suppose that it's physically impossible. So how do you do that? If you think only in the Finish we start a relationship.

How do you do your link? First, the second to the turd, to the fourth floor, the construction in a finished to start then do you link the paint finished to start on each floor and then the furniture on Finish to start or on each floor. And then you leave the treatment on the floor is the normal. Everything is fine, but there is one problem let's suppose that I have pre-teens. One is the construction team that will do the first task. The second is the painting team and the turd is the moving team that will we'll move the furniture.

What happen with the second team? So look, after four days, you are ready with the walls on the first floor. Then you start painting in two bass. You already painted the first floor, but what happened with the second floor? The second, the floor, it is not ready yet to be painted. So what happens with the painters? They need to wait two days, right? They need to wait. Today's because up until the second floor is ready. So the painter's will work to days with a gap of two days, two days with our gap of today, this is just a very simple example.

So we imagined we pay them Daly, what will happen? I we'll be in trouble because most of the time I will not have the chance of saying, please go back home and come back in two days and I pay you only to work and I need to pay from the beginning to the hand. So I knew that to consolidate that So what is that? The idea of this start to finish. I due on the first work, the construction I do all finished to start first, second, third, and fourth floor then. And what I do, I go back on the paint using, I start to finish it's something going backwards on the start to finish.

I put, okay, as soon as I finished the four floor, I can start the painting. Right? But to start the painting on the fourth floor, I need to finish the painting on the third. And then I go back. I do backwards. So I do all start to finish. If you want to, you can see this in my paper, the drawing on that. And then I go, Finish the Start on the turret. So I use the start to finish to make sure that there is no gap. And at the end, I realized that I should start the painting, not the day after the one of the first floor, but maybe five days after.

And why is this gap? Because this gap it's not needed that I paint. The first four is such a high speed. It's much better that I weight and then a concentrate, all of the painting, work on that timeframe. So this is a great use. So just to wrap up the concept of start to finish, you need to understand where the problem is when you have finished with Start. The problem is that the tasks that will start is just the waiting the other one, two Finish right, but they start to finish.

It's a little bit different. I'm ready to Finish I'm just waiting the previous one to start. So let me give you two very good examples. The first one let's suppose you are replacing them a server, a computer server. So let's suppose you have the old and the new one and you want to replace them. What's the problem. The problem is not to turn off the old one. The problem is to turn on the new one, because to turn off the old one, you go to the whirlwind and plug the wall and that's fine.

You it's off. The problem is that you can only do that when the new one is a starting So the new in each two Start so you can, Finish the old one second example that I love mentioned that you have a security. So imagine that you have a security officer in your building, and then it's time to shift the turn. What's the problem. The problem is not the current officer to leave, because if you leave, we can have Finish to start the security office and then to live the Finish sold the new officer now to start.

So when it's slime, the security officer just pack his stuff and leaves. This is not, what do you want? What do you want? Do you want it that the current security officer is stays there until you are sure that the knew what the incoming security officer is starts working. Otherwise your beauty will be without protection on that time. So this is a classical example of start to finish. So I hope now that you had the ability to understand, because this is what else, the more two on the, your Swiss army knife, when you were planning your time, there are some very good, Hey, is, is where you can benefit heavily from this kind of start to finish approach.

So I hope you enjoyed this podcast. Sorry for being very technical. Does time see you next week with another five minutes PM. Podcast.

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