In the bar chart or a Gantt chart there are several advantages and several disadvantages. But, let me highlight the advantages first. One, simplicity, it's very easy to read and to understood and also it's very easy to prepare as you just saw a couple of slides before. Very effective as a communication tool between engineer and the foreman, or an engineer and the client or executives in your company as so on. Because not much complicated calculations are involved in bar charts. Know basic theory, and anyone can understand it from the all types of levels in the construction projects and the companies. However, with bar charts, there are limitations and major disadvantages. One, the job logic, one major disadvantage of traditional bar chart is the lack of precision in establishing the exact sequence between the construction activities or the work items. It does not clearly show the job logic and among this list of activities. And sometimes this is solved by providing arrows between each activity, like at the end of each bar, you can have an arrow going to another bar to show the relationship between the two activities that this will finish. And this other activity is depending on the one before it. This refers too, as either a barbet or time scaled logic diagrams. In my humble opinion, and the literature that I saw and I read here, I would not recommend this kind of approach because it will make it more complicated. It will make it very connected and all lines between the bars and the arrows it will not look good. You are actually making it more problematic for a scheduler or the means of effective communication and simplicity. That's why I will be talking about other scheduling tools for later in this course about networks, or activity on arrows and activity on nodes. The second disadvantage is delaying activity impact. What we mean by that, it's ineffective, the bar charts, to determine the impact when we delay one construction activity, like the bar chart, and we say, let's move it a little bit, on a project in this schedule. And how that will affect the entire duration of the project. So let's say I moved one of the projects, or one of the bars. Sometimes moving it one day, can affect the finished time of the project by one day. Sometimes you don't affect it at all. And sometimes it's affecting it with more than one day. So, for the bar chart tool or schedule tool, it's very hard to tell and answer this kind of question. Also, the number of activities, it's basically, it's very difficult to comprehend logic when the number of construction activities and the list of activities increase. So if you have a huge project you will not be able to highlight all these bar charts. You're just making one page to be able to understand it from A to Z, it's going to be cumbersome. So bar charts may not be practical for projects with huge number of construction activities unless sometimes that you are using this kind of scheduling tool in certain ways. For example, you can use a bar chart to show a specific section or subset of activities to maintain simplicity. Such as if you want to show let's say a subcontractor or a top management team with a client or within your company, bar charts for certain activities in certain time. Or certain activities for only specific types of activities like critical ones. And we will talk more in details for later about what we mean about critical activities. Or you want to show a list of activities in certain location of a project or those that will be run by only specific subcontractor. So in this case you highlight that, it's something simple. You show it to the subcontractor and that's what you work on, that location, okay. Here's the bar charts and this is for that specific location, in this tower, in this floor in the tower, in that section, in the east side of that floor, and so on. Another example where would you use it, even if the project is really big, is to show only somebody of bars. As I explained in the introduction, some of the bars would be a combination of a lot of activities. So, each bar in this case represent a group, of other activities, or a smaller activities. We can use such an example in the planning phase of the project. Or maybe, when you present to the top management team from your company, or the top executives from the client side. In this case, they come, they ask you what's the situation we have here? How are we doing in our project? Then you can highlight it in a simple bar chart from all the big components. If you remember when we talked of that planning course and the initiation of a project at this series or this specialization, we highlight the work breakdown structure. When we refer to the higher level of the bar charts representation, I mean to talk about or to refer to the work break down structure in the higher level in the hierarchy, not the way lower level. So that's also very useful, simple, straight-forward you can use it and I'll wrap up here by one last advantage we have for the bar chart, is the useful in identifying required resources. And we highlight this kind of example for you about when we use the budgets. Sometimes it's very effective, for example, when you have the bar chart and highlighting okay how many labors I will be using in that specific activity. And that is sometimes very useful actually, just look at the y-axis, look at how many labors. As you as a construction manager, or project manager, you will be able to plan ahead of time when exactly how I'm going to manage my resources, my time, my money all that four M's in construction projects. My materials, man power, machines and money on delivering the project at the end. So this is what are the advantages and the limitations and the disadvantages of a bar or Gantt chart.