Welcome back to our course on Project 2013.
In the previous section we looked at tasks in Project 2013 and in this section we’re
going to look at the basics of dependencies.
I closed down the last project that I was working on and when I restart Project now
I find that I’ve got two projects in the recent list on the start screen.
I’m going to restart from example_01 which is the first sample file in the list of files
provided with the course.
If you’re working along with his using perhaps your own project, then if you open that there’s
absolutely no reason why you shouldn’t carry on working on your own project.
But I’m going to use this one so all I have to do is to click on the file name in the
recent list and that project will reopen and that’s exactly how we left it at the end
of the previous section.
Now when we talk about dependencies within a project, we’re talking about the need
for one thing to happen before another can happen.
So for instance, I’m not going to fit the roof until I’ve fitted the windows and doors
to the walls or in fact is that true?
Could I not fit the roof as soon as I had the walls built?
That would make sense.
I don’t actually need the windows and doors to be in place before I fit the roof so maybe
this sequence should be build walls, then fit roof, then fit windows and doors.
But on the other hand, couldn’t I be fitting the windows and doors at the same time that
I’m fitting the roof?
They both need the walls but neither needs the other.
So we quite often find that when it comes to putting things in sequence, when we look
at these dependencies, they maybe not as straightforward as they might at first appear to be.
But let’s start with one of the very simple dependencies and let’s look at the dependency
between Prepare site and Lay foundation.
Now at the moment, Prepare the site and Lay foundation follow in sequence anyway purely
because of the dates they’ve been given to start on.
But if I want to force Project 2013 to insist that Lay foundation cannot happen until Prepare
site has happened, I can establish a link between the two tasks.
Now you could do this in a number of ways but the simplest way is this: Select the first
task which means the row is highlighted in the table, hold the Control key down, select
the second task, and then on the Task tab on the Ribbon in the Schedule Group, there
is a pair of chain links and one of them is Link the selected tasks and one of them is
Unlink the tasks.
On this occasion, I want to link the tasks so I click on Link and what happens is a link
is added between the two.
And in the Gantt Chart, you’ll see it’s represented as a little arrow and you’ll
notice that that little arrow comes out the right hand end of Prepare site and goes into
the left hand end of Lay foundation.
Now you’ll soon find when you’re reading Gantt Charts that you immediately see what
the relationship between those two tasks is, and that is that the second task cannot begin
until the first task has finished.
Now let’s do that again but this time we’re going to say that we cannot build the walls
until we’ve laid the foundation.
So select Lay foundations first, hold the Control key down, select Build walls, click
on Link, and now you can see that Project has started to reschedule the work on the
build because it’s actually changed the start date for Building walls so that we don’t
start building the walls until we’ve laid the foundations.
So now we can see the dynamic nature of Project as we add or change dependencies between the
tasks.
Now I’m assuming that the house we’re building here is a pretty straightforward
house so I’m going to now put in the next link which I think is pretty straightforward
and that is Build the walls.
The walls have to all be completely built before we can fit the roof.
So I’ve selected Build walls, Control, select Fit roof.
Note the selected tasks don’t need to be next to each other.
Click on Link again and fitting the roof goes out to there.
Now this task, Fit windows and doors, offers a couple more really interesting questions
in terms of dependencies.
So let’s look at some things related to fitting the windows and doors.
First of all, do we have to have finished fitting the windows and doors before we fit
the roof?
The answer to that is no.
There are plenty of houses around where I live which have got the roof on, the walls
are all built, but maybe half of the windows still haven’t been fitted yet.
So you certainly haven’t got to finish fitting the windows and doors before you fit the roof.
Must the walls be completely built before you fit the windows and doors?
Well, no they don’t.
You might for instance in a two story house as soon as you’ve done the walls for the
lower story, you can certainly fit the windows and doors to the lower story.
You may even be able to start fitting windows and doors before you’ve finished the walls
on the first story.
So the dependency there is a lot less absolute, a lot less clear, and we’ll talk about those
less clear dependencies later on.
Do you have to have laid the foundations before you fit the windows and doors?
I think yes you reasonably do.
And you would certainly have had to start building the walls.
So we come to a conclusion in something like this that the dependency is a little bit more
complicated.
Something along the lines of well I will have had to do some building of the walls before
I can fit windows and doors.
But then once I’ve done a certain amount of work on the walls, I can start fitting
the windows and doors, and that’s the sort of dependency that we’re going to add a
little bit later on.
However, what I’m going to do for the moment just to make our project a little bit more
realistic is I am going to assume that we’re going to finish building the walls before
we fit the windows and doors.
So I’m going to put in the same type of dependency that we’ve had before.
A simple link there and now we can see that I will in effect be fitting the windows and
doors and fitting the roof at the same time.
And the whole build will be finished what around about the end of April by the look
of it.
So as you can see I’ve setup a few fairly straightforward dependencies there.
If you point at one of the dependencies, one of those little arrows and double click on
it you open up a Task Dependency dialog, and this gives you details of the kind of dependency
that you’ve got.
So the dependency here is from Lay foundation to Build walls.
There are four types of dependency.
This is a finish to start which means that Lay foundation must finish before Build walls
starts.
We normally use a letter abbreviation here.
So finish to start is FS.
The four types in total are finish to start, start to start, finish to finish, and start
to finish, and then we can build in what’s called a lag.
I’m going to talk about lag later on and that’s the one that we’ll use to make
all of that a little bit more realistic, but we’ll be looking at that later on.
And if you want to delete a dependency, you’ve got a Delete button there.
So that’s one way of looking at a task dependency.
Let me just cancel that and let me now click on Fit windows and doors.
Let me double click and bring up that Task Information dialog again.
In the Task Information dialog, you have one tab Predecessors and this tells you what the
predecessor tasks are.
Now the predecessor task there is only one for Fit windows and doors is Build walls.
It’s ID number three.
I mentioned the ID numbers earlier on.
This is how you uniquely identify a task in Project 2013.
So the only predecessor currently of Fit windows and doors is Build walls ID 3.
The type of dependency is FS with a zero day lag, and that in its very basic form is how
to setup a dependency between tasks.
Note that it’s not necessary for the first task to be physically above the second task
in the Microsoft Project list.
These tasks can be in any sequence.
So if I had chosen Build walls first and Lay foundation second and created a link Lay foundation
would have followed Build walls.
They don’t have to be in the sequence that you can see there, although I always I find
it’s much easier to follow if they are more or less in that chronological sequence.
So that’s it on dependencies for the moment.
We need to look at those in quite a bit more detail later on.
That’s it for this section.
I’ll see you in the next one.