Task dependencies are something which you will likely be familiar with if you are working within projects and using Microsoft Project or Primavera P6. There are however some which are less common than others and therefore may appear more complicated.
Dependency types are not difficult to understand however a good explanation is often required to fully realize the meaning. Simply put, task dependencies refer to the relationship held between each task within a project.
Within this article I will talk you through the meaning behind Start to Start dependencies, one of the four dependency types, using industry examples to help explain how it can be used.
See also these related articles:
Start to Start dependency: What does it really mean?
Start-to-Start dependency is one of the less common task dependencies therefore you may not be as familiar with it and that may be why you have found yourself here reading this article. Not to worry, I can help!
A Start-to-Start (or SS) dependency means that a successor activity cannot begin before its predecessor has started. They do not however have to start at the same time. These dependencies are common within projects which require their tasks to run parallel to one another.
Why is it called “Start-to-Start”?
Using every-day language to describe this type of dependency, it would sound like this:
“Task B can only begin once Task A has started”.
Start-to-Start task dependency examples:
There may be times when you are required to schedule Start-to-Start task dependencies within your own projects. The following examples will help you recognize how and when this type of dependency can be used:
Example 1: Decorating
For this example imagine you are overseeing the decoration of two rooms in a house. One room is to be painted, the other is to have wallpaper hung. You have a specific start date in mind for this project and you will have both a painter and a decorator available to paint and hang wallpaper at the same time; ensuring they are working alongside one another to guarantee a short project duration. There are two tasks required in this project.
- Task 1: Paint room one
- Task 2: Hang wallpaper in room two
As there is a specific project start-date, both tasks are required to begin on the same day and therefore one cannot begin without the other. As the successor cannot start until its predecessor has, even if they are starting at the same time, this scenario is an example of a Start-to-Start dependency type.
Example 2: Construction
Imagine you are planning the work on a construction site and have to organise the external decoration of the buildings. There are two tasks required for this.
- Task 1: Assemble scaffolding
- Task 2: Paint exterior
In order to begin painting the building, there must be assembled scaffolding in place which can be used. The task “paint exterior” therefore cannot begin until the task “assemble scaffolding” has been started. This is an example of a Start-to-Start task dependency as task 2 can only begin once task 1 has started.
Example 3: IT (Load testing in IT implementations)
Imagine a company is in the process of rolling out a new SAP system that is going to be used in all of their global locations.
Before the system goes live, it is standard protocol to perform a load test (or stress test) in order to see if the system can handle the actual transaction volume. Before the actual load test can start, it is important to have the monitoring processes set up and running in order to measure the transaction performance.
This is therefore an example of a Start-to-Start dependency because load testing should not start until system monitoring has begun. The corresponding tasks are:
- Task 1: Enable system monitoring
- Task 2: Begin load testing
Creating a Start-to-Start dependency in Microsoft Project
To set a Start-to-Start dependency for your tasks in MS Project, simply follow these steps:
- Enter tasks in the list without linking them
- Double click on the successor task
- Go to “Predecessors” tab
- Enter the predecessor number under “ID” and select “Start-to-Start” dependency type
Here are some screenshots to help:
As you can see the Gantt Chart shows the Start-to-Start dependency between the two tasks, represented by the arrow. This arrow implies that the successor activity cannot start until its predecessor has started.
If, however, you would like your Start-to-Start dependent tasks to begin on different dates, you can enter a time lag in the predecessors table within the “Task Information” window as seen in the first screenshot.
Regardless of your project it is important to recognise task dependency types as they will allow you to provide effective scheduling. I hope this article has helped you to better understand Start-to-Start dependencies and how they can be used successfully within your own projects.