When creating a project schedule, it is crucial to identify and account for dependencies between tasks. In project management, dependency is defined as a relationship between two tasks in which the completion of one task is dependent on the completion of the other task.
Different types of dependencies can be identified in project schedules, and each type has its own set of implications for project planning and execution.
This blog post will discuss the role of dependencies in project management, the different types of dependencies in project schedules, and offer some examples.
Dependencies in project management are connections between tasks on a project timeline. These dependencies determine sequencing and resource delegation in every project.
Before we go into the different types of dependencies, here’s a crash course for the most important terms to know related to this stage of project management.
Constraints are project limitations—in essence, they can all be stripped down to three main restrictions:
Lead and lag time are durations that project managers can add between two tasks. Lead time is the duration in which the following task will begin before its preceding one ends, while lag time is when a project manager decides to push back the beginning of a task after another one ends (i.e., creating distance).
The critical path is the project timeline that project managers create to determine which tasks are mandatory and must be completed on time. In other words, it’s a schedule of project dependencies with no slack time or lag/lead times in between.
Logical dependencies are the usual project dependencies that project managers usually encounter. These dependencies reflect the sequence of tasks and their logical relationship to each other. You can think of them as “if this, then that” relationships between project tasks.
Resource dependencies occur when a project task cannot be started or completed until the required resources become available. These dependencies are restricted by cost, time, or the overall scope of the project (constraints).
In the case of preferential dependencies, some tasks are given a preferred status over others—when project managers prioritize project tasks by using a must-do, should-do, and nice-to-do approach.
Sequential dependencies are project dependencies that must be completed in a specific order. These types of dependencies can often be found in project processes where tasks are divided into smaller work packages with multiple steps. Once project managers complete a project task, they can go to the following project deliverable.
External dependencies are project dependencies that come from outside of the project. They can be caused by factors such as natural disasters, changes in government policy, and supplier failure.
E.g., if you’re a construction manager and a supplier doesn’t deliver the correct materials on time, it will delay your project timeline.
Project dependencies can be a cause of project delays and should be taken into account when planning projects.
FS refers to project tasks that require project managers and their teams to complete one task before they can move on to the next. This is the most commonly used dependency in project management. It’s when project managers finish a project task before they start another one.
FF project dependencies are where two project tasks are required for completion at nearly the same time or within a specified period from each other. It’s when project managers finish two project tasks simultaneously or soon after one another instead of finishing one before starting on the next task.
SF project dependencies are tasks that require project managers to start one project task first before completing another project task. This is an uncommon type of dependency in project management because dependencies can often be completed in any order.
SS project dependencies are where two project tasks are dependent on each other, starting at nearly the same time or within a specified period from each other. This is the least common type of dependency in project management.
It’s when project managers start two project tasks simultaneously or soon after one another instead of finishing them first before starting on the next project task.
Project managers should use project dependencies when planning project work to understand how project tasks are connected and which project tasks must be completed first before starting other project tasks.
By understanding the logic of it, you’ll also be able to see what a delay might mean for your project timeline and whether there are types of dependencies that may not make sense.
In construction management, projects often involve external factors such as suppliers, local government policies, weather conditions, or natural disasters.
These external factors can cause delays because the project manager has less control over them than their internal colleagues or team members who help deliver the project on time with minimum defects. In this case, it would make sense for project managers in construction to use project dependencies to plan their project work.
In product development, projects often involve multiple stakeholders and team members who may have different views on the final product.
This can cause delays because project managers need consensus from everyone involved before making decisions that impact how long it takes them to deliver their project or if something doesn’t meet expectations during delivery.
In this case, it would make sense for project managers in product management to use project dependencies to plan out when things will be ready so that there aren’t any surprises later down the line by using logic behind what needs to be done first before other project tasks.
In project management, dependencies are an essential part of the process. By understanding the different types and how they work, you can better manage your projects and ensure that everything is completed on time and to specification. This article looked at the role of dependencies, three common types, and some examples of each type.
While there are other types of dependencies out there, these are some of the most commonly seen in project management. As always, if you have any questions or need help planning your project, don’t hesitate to reach out to a professional.