Ihab Saad – ADM solved example
AI: Summary ©
AI: Transcript ©
I Hello again. Today we're going to start trying to solve the
problem with ADM to see how can we draw the network, and how can we
perform the calculations of error Diagramming Method. What we have
here in front of us is a table showing different activities in
the form of ij, together with the IPAS and the durations for each
activities, for each one of the activities. So what we're going to
do is, first, we're going to try to draw this network. Here we have
an Excel file. We're going to try to draw the the network in Excel.
And that's basically a very simple task. What we're going to do is
we're going to go to insert
and shapes. We're going to select a an oval, which we're going to
make, like a circle here,
and then what we're going to do, basically, is just copy and paste
this circle several times,
and now we're going to start dragging these circles one by one
and drawing the network. So we start with activity AB, of course,
as we notice here, we have ab, ac and ad. All of these three
activities have no immediate predecessors. So
we notice that these three activities have no immediate
predecessors, which means that they start the network. So we're
going to start with node A, and then draw activity ab, ac and ad.
So we're going to drag one of these circles here, and that's
going to be the node A. You can type a inside like that,
and then we're gonna add drag another node here,
B, another node
C and another node D.
So here we have
B,
C
and D.
What we're going to do next is we're going to connect these with
a line. So we're going to select shapes. We can select an arrow, as
we mentioned before, an arrow or a line doesn't make much difference,
since we know that the flow is going to be from left to right, so
we're going to connect AB,
we're going To connect
AC,
and we're going to connect ad.
So here we're done with the first three activities. Next we're going
to look from B we have activity B, C and B, E, and both of them have
a B as predecessor. So we're gonna drag two nodes here. So
and connect,
and here we have
BC.
Well, actually, BC is already here, so we don't need to drag a
couple of nodes. We can just connect BC like that.
And that's going to be be,
but notice something here,
activity BC has zero duration,
therefore it has to be a dummy activity. So what we're going to
do, we're going to change the properties of this line,
going to format shape by right clicking on the line and changing
it into a dash type, something like that.
And here we have it on the activity between B and C, B and C.
So then we have CF, which follows AC and BC
CF. So let's just drag this node here,
and this is going to be f,
and draw the line CF and
okay,
and then we have CG, also has predecessors of AC and BC, so we
have g is.
Going to be somewhere here. So let's drag another node G,
and the activity
connecting the two nodes. Remember, in ATM, the activity is
represented by the arrow connecting the two nodes,
and then we have also DG, which has as a predecessor, ad. So we're
going to connect DG,
so it's very convenient that we place G at this position. Now you
can you're going to see that we're going to have some different
attempts at arranging these activities in the proper layout to
be legible as much as possible. So far, it's working fine,
alright. So next we have activity EI
and EF, and both of them have, as predecessors, be so EI and EF,
dragging two nodes, actually one node only, because here we have F
already existing. So we're going to connect EI. This is going to be
I
connect Ei,
and also connect EF. We're
both of them have duration. So we only, as you notice from this
table, we only have one dummy activity, which is activity, BC,
all right, so now the next one is going to be G, H, which has as
predecessors, CG and DG. So we're going to have H somewhere here,
and we're going to connect
GH.
Next we have f j, F j, which has as predecessors, E, F and C, F. So
let's put J somewhere here
and connect
F j, so
and then we also have HJ and ij. We already have the node, so all
we have to do is connect i
i,
and here we have our network.
We have all the activities,
i, j
as its predecessor, e, i, that's fine. And HJ has its predecessor,
GH, that's perfectly fine. So we ended up with one extra node. We
can just delete that
very well. The next step is to calculate the dates. As you
remember, we mentioned that we're always going to start with day
zero, so we're going to put zero here, and zero, also here and zero
also here.
Let's just make some adjustments so that it appears in a nicer way.
And here we're going to make it like that.
Actually, you can try to Okay, so far so good.
And then activity AB has a duration of four days, so we're
gonna finish on day four.
So also, let's make it left adjusted.
Activity AC has a duration of nine days,
so it's going to finish on day nine.
Ad has a duration of 16 days, so it's going to finish on day 16. I
now activity, the node B has the date number four, so anything that
starts from B is going to be on four. So we're going to put four
here
and four here as well.
Now activity be has a duration of 13 days, so it's going to end on
day 17. So.
The Activity BC is a dummy activity, so the duration is four,
therefore it's going to end on day four as well.
Centered.
Now at node C, we have two dates coming we have four coming from
BC, and we have nine coming from AC. As you remember from our
lecture, we're going to take the larger number in the forward pass,
so we're going to put here nine
and nine.
Duration of CG is 14 days, so it's going to end on day 23
and duration of CF is seven days, so it's going to end on day 16.
Duration of d G is
eight days. It's going to start on day 16,
and it's going to end on day 24 I
now at node G again, we have two numbers. We have 23 and 24
therefore the number that's going to proceed with us is going to be
the 24 the larger number.
GH has a duration of 12 days, so it's going to end on day 36
and
as you can see, it's very simple calculations. We can just you can
just finish the calculations for this network. Let's just finish
the forward pass, and you can go ahead and do the backward pass
yourself.
So here we're going to start with 17 i
and EI
is 16 days. So it's going to be 33
here. Also we have 17
and EF has a duration of nine days. So it's going to be 26
so at node F, we have 16 and 26 we're going to take the 26
and F, J has a duration of 10 days. So here we're going to have
36
and then I we have here 33
and duration of ij is 13, so it's going to be
46 40 6h.
J is going to start here on 36
and has a duration of 11 days. So it's going to be 47
now we have three numbers going to know, j we have 4636 and 47 the
largest number, of course, is 47 so that's going to be my end of
the project. The project started on day zero and ended on day 47
as you can see, the calculations are not that hard at all. They are
very straightforward and simple. What we're going to do in the
backward pass, actually, is reverse everything that we did in
the forward pass. Let me start the backward pass and leave it for you
to finish. So let's start with the first set of activities. Here,
we're going to start with 47 as the late start, which is going to
be underneath the arrow 47 and let's change the color of these to
be red, for example,
just to distinguish the forward from the backward passes. So 47
the duration of HJ was
11 days. So it's going to be 36
now we're subtracting. Remember, I.
Now you notice here that HJ has 4747 3636 so obviously this is
going to be a critical activity. Right now, if you follow that,
you're going to find that the critical path is going to be
basically that bottom path,
because this is going to be the longest path, leading with giving
us the longest dates, the latest dates. So it's going to be a, d,
g, h j, that's going to be our critical path at the end. How did
I know that? Because it has to be a continuous path. And since it
passes through h j, then it has to be that one. Why didn't we say a C
and C G? Because again, the number coming to G from D, which is 24 is
larger than the number coming from C, which is 23 therefore the
critical activity is going to be DG. But let's go ahead and do a
couple more activities with the dates. So here we're going to
start with 47 as well, and
let's put
it here,
red 47 minus 10, that's going to be 37
now notice this activity has how many days of total float 47 minus
36 or 37 minus 26 which is 11 days of total float going to activity,
i j, it's going to be again 47
minus.
This is i j
minus 13, so it's going to be 34
and you can just keep doing the backward pass. This one is going
to have only one day of total float. What we can also do at the
end, we can just change the color of the nodes that are going to be
critical.
So we're going to make it something like this,
just to show them in a different color, so that they have a special
status as critical activities.
And we can also change the color of these lines. We're going to
select this group of lines, 1234,
activities, and right click Format objects. Change the color line
color. Let's make it red as critical
and here's our critical path. That was really simple, wasn't it? So
what you have to do is finish that as a as a practice, try to finish
this network and see if you're going to get the same numbers for
activities, GH, Bg and A, D, which should be critical, and then
calculate the total float for the other activities. That's basically
our exercise for today. So.