Here are the main five points I want you to understand when you think about critical path in your schedule. Also, the slide shows the importance of any critical path and why you need to know it from planning, from critical scheduling, and controlling tasks of your construction project. So let's start from the first one. All construction projects have at least one critical path. So, we could have more than two if, for example, let's just go back here. We have activity D here, has a duration of 16 days instead of 13 days. So guess what's going to happen? We're going to have the total duration of the path A, D and G which is the last one here will be also equal 18 days. So that will lead us that we have two critical paths in our project. Also more than one critical path may exist and multiple path may share also some activities. For example we shared activity A, and we shared activity G, in two critical duration paths in case we have activity D duration is 16 instead of 30 Second, all the critical activities belong to a critical path. An activity cannot be critical without being at a critical path. This is very important. Also, if all paths at your construction project go through one particular activity, all the paths that you have, the combinations, the sequences of the activities. All of them, they go through one particular activity, then that activity must be critical. 3. A delay in any critical activity will extend the project duration. That means, if you have the previous example and you delayed one of the critical because it is the longest, which makes sense that it's going to go furthermore and I will explain why this is important when we speak with the last point. Number 4. The noncritical activities can be delayed at least 1 day without lengthening the project duration. This will also cover it for later module when we discuss about floats and the importance why we have floats at the noncritical activities. And what is the float for critical activities versus noncritical activities? So for number 3 and 4, I want to combine them with a main point we have in number 5 here. Which is, saving time in any noncritical activity does not decrease at all your construction project total duration. So let's think for awhile here. You want to focus more on the critical activities. When you shorten one of the critical activity duration, that will shorten the critical path duration itself. So if you want to think about it, you do have several a critical path of the projects instead of one, the example before we highlighted if activity D is 16 instead of 13 so we have two critical paths. So if you do have several critical paths in the project, you need then to focus if you want to shorten the duration of your project to shortening all the paths that you have in your project with the same duration. Also, once you shorten a duration, and this in important, once you shorten a duration for a critical path, you might actually generate another critical path that it was not critical before. So if you have a total duration of 18, for the longest path, the critical path, and then the following one is 17, and you shorten the longest one for two days, it would become 16 days. So you have that path is non critical anymore. And you will generate another renewed path to be your critical path for your project. So again once you shorten the duration for a critical path, you might actually generate another critical path that it was not critical before. So, you know what? Let's take, because this is important, let's take an example. If we want to shorten an activity, let's go to example here. Shorten activity B on this critical path, to six days instead of 9. What's going happen here? If we have activity B into 6 days, and activity B will go to this one here, so we have a total duration on this path equal 18 minus 3 which equals 15 days. That will give us actually three critical paths generated in my project. Which will be the first, ABEG, 15 days, if we have instead of 9 6, so ABEG is 15 days, ACEG will be also 15 and the ADG also will be 15 days. So, let's go back here, why this is important? If we have, as a construction manager as PM for my project and I have two activities, construction activities that have conflict of resources use, I always go with choosing the critical one to perform not the non-critical. Because if you want to save time or let's say you are delayed and you want to expedite the project, you cannot just ask for an overtime for your labors or workers or engineers or have your labors and the team come show up on weekends. Especially if this work will be only for in a noncritical activities. You need to make sure to focus all that effort and this extra time overtime or to work over weekends more on the critical activities. So, don't waste your time and money on non critical activities. If it will not help in shortening the duration of the project, you know what's going to happen? You are just increasing the budget and the costs of your project. So if you have a situation in your project that you are running out of time, you are, let say behind the schedule and you want to expedite more in the duration, you want to go and focus more on that critical activities you have in your project. And if you remember what we said from cost number 1 planning is everything that plans are nothing. Why I said that? Because once you focus more on critical activities and manage to shorten these activities by one or two days that by itself might create another critical path as just explained. So that's why planning is a continuous process, once you do update on some of the critical activities, you have to go and the plan and do the schedule and read it again and again and again. To make sure every specific period of time, to look at the schedule, update the schedule to make sure where are your critical path in your project.
