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How long will it take? Find out if you should schedule your project top-down or bottom up.

Published by Rebecca Bernsen September 24, 2020 Estimated reading time: 5 minutes

The most frequent questions you will get asked when managing a project are probably: When will you be finished? And: How long will it take? It might be annoying for you to hear the same questions repeatedly but it shows how essential it is to plan a project thoroughly and to keep your team as well as your stakeholders up to date.

Project planning is essential as it has immediate effect on the project’s results. With good planning you avoid work that does not contribute to your objective and you will be able to execute faster. After having set up a good project plan, you will be more involved in controlling and managing risks - instead of improvising and running day by day. In essence, with accurate planning, better quality results are created faster. Your stakeholders will be happy to be up to date, knowing you are managing a well-planned project and your team members will value and respect you as a foresighted manager.

Scheduling a project

In this article we want to focus on planning in the sense of scheduling, i.e. setting up a timeline for your project. You as the project manager are responsible to determine your project’s timeline. In order to make your project a success, you want to get a plan that is as detailed as possible. Nevertheless, you need to consider that there are many unknown variables. How could you approach this and what could help you?

In general, there are two ways of scheduling a project. OpenProject supports both project scheduling methods, top-down and bottom-up, and you can switch between them or even combine both according to your needs.

What is top-down scheduling?

The top-down approach aims at moving from the bigger tasks into smaller tasks, from the overall into the specific. It can be the case that the start and finish date are known but not all sub-tasks are known when planning the project.

That means, you start by defining the bigger, known milestones or objectives. From there you get into the sub-tasks in the project that help achieving your known objectives. The breaking down of milestones can happen over time, whilst working on the project. You will granularly define sub-tasks and next steps. In order to define the sub-tasks, you can involve your organization to give input and help specifying.

With the top-down plan you would need to make assumptions as many details will be missing at the start of the project. That is why you could lack accuracy and have unrealistic targets. Nevertheless, the top-down planning allows for a short and straight forward planning phase. The advantage then is that you have a solid basis for a quick budget and resource planning. Of course, final budget and date commitments should only be done once detailed planning is completed.

According to the top-down planning, in OpenProject you would use the “manual scheduling mode”. That means, you can plan the start and finish dates of parent and children tasks independently. You can schedule your milestones and objectives (parent work packages) with their timing and add independent sub-tasks (children work packages) that do not affect the timing of the superordinate task. That gives you the flexibility to adjust the timing of the children work packages as you go along and learn more about the children’s details. At the same time, your overall plan of objectives will remain untouched.

What is bottom-up scheduling?

The bottom-up approach is - as the name suggests - the opposite of top-down. You plan from the detail to the bigger picture. Thus, this approach takes much more time in the planning phase. But in return it also generates the more accurate plan. The project team starts planning the detailed tasks and make accurate estimations about timings at a detailed level because they are the experts. The dependencies between these detailed tasks will then determine the overall timeline for the project.

When creating a bottom-up project plan in OpenProject, the easiest is to use the “automatic scheduling mode”. The timing of the children work packages and their dependencies then automatically determine the parent work packages duration. So, if you are e.g. extending the duration of a child work package, the parent work package will automatically get extended as well.

Application of project scheduling

In most cases, both approaches are combined, because the more precise a planning is, the more efficiently, especially in terms of time and costs, a project can be managed. But on the other hand, the more accurate the planning, the more time and costs the planning will consume. Thus, you would want to balance planning accuracy versus costs of the planning.

However, there are some recommendations which of the planning approaches should get more weight in certain cases: The top-down planning could be used to plan a project portfolio and determine the resources needed to execute the projects and consequently get early buy-in for budget and staff requirements. Bottom-up planning is used more when the accuracy of the project plan plays a vital role, e.g. planning specific products for a region, where the planning is relying on a lot of information from different experts.

OpenProject allows you to switch between the different planning methods and combine both at any time just with a single click.