Example

For the first example let us consider the rather mundane operation of getting up in the morning, and let us look at the constituent activities between the alarm going off and boarding our train to the office.

The list of activities - not necessarily in their correct sequence - is roughly as follows:

Time (min)

A switch off alarm clock

0.05

B lie back and collect your thoughts

2.0

C get out of bed

0.05

D go to the bathroom

0.10

E wash or shower

6.0

F brush teeth

3.0

G brush hair

3.0

H shave (if you are a man)

4.0

J boil water for tea

2.0

K pour tea

0.10

L make toast

3.0

M fry eggs

4.0

N serve breakfast

1.0

P eat breakfast

8.0

Q clean shoes

2.0

R kiss wife goodbye

0.10

S don coat

0.05

T walk to station

8.0

U queue and buy ticket

3.0

V board train

1.0

50.45

The operations listed above can be represented diagrammatically in a network. This would look something like that shown in Figure 26.1.

It will be seen that the activities are all joined in one long string, starting with A (switch off alarm) and ending with V (board train). If we give each activity a time duration, we can

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Figure 26.1

easily calculate the total time taken to perform the complete operation by simply adding up the individual durations. In the example given, this total time - or project duration - is 50.45 minutes. In theory, therefore, if any operation takes a fraction of a minute longer, we will miss our train. Consequently, each activity becomes critical and the whole sequence can be seen to be on the critical path.

In practice, however, we will obviously try to make up the time lost on an activity by speeding up a subsequent one. Thus, if we burn the toast and have to make a new piece, we can make up the time by running to the station instead of walking. We know that we can do this because we have a built-in margin or float in the journey to the station. This float is, of course, the difference between the time taken to walk and run to the station. In other words, the path is not as critical as it might appear, i.e. we have not in our original sequence - or network -pared each activity down to its minimum duration. We had something up our sleeve.

However, let us suppose that we cannot run to the station because we have a bad knee; how then can we make up lost time? This is where network analysis comes in. Let us look at the activities succeeding the making of toast (L) and see how we can make up the lost time of, say, two minutes. The remaining activities are:

Times (min)

M fry eggs

4.0

N serve breakfast

1.0

P eat breakfast

8.0

Q clean shoes

2.0

R kiss wife goodbye

0.10

S don coat

0.05

T walk to station

8.0

U queue and buy ticket

3.0

V board train

1.0

27.15

The total time taken to perform these activities is 27.15 minutes.

The first question therefore is, have we any activity which is unnecessary? Yes. We need not kiss the wife goodbye. But this only saves us 0.1 minute and the saving is of little benefit.

Figure 26.2

Figure 26.2

Besides, it could have serious repercussions. The second question must therefore be, are there any activities which we can perform simultaneously? Yes. We can clean our shoes while the eggs fry. The network shown in Figure 26.2 can thus be redrawn as demonstrated in Figure 26.3. The total now from M to V adds up to 25.15 minutes. We have, therefore, made up our lost two minutes without apparent extra effort. All we have to do is to move the shoe-cleaning box to a position in the kitchen where we can keep a sharp eye on the eggs while they fry.

Encouraged by this success, let us now re-examine the whole operation to see how else we can save a few minutes, since a few moments extra in bed are well worth saving. Let us therefore see what other activities can be performed simultaneously:

1 We could brush our teeth under the shower;

2 We could put the kettle on before we shaved so that it boils while we shave;

3 We could make the toast while the kettle boils or while we fry the eggs;

4 We could forget about the ticket and pay the ticket collector at the other end;

5 We can clean our shoes while the eggs fry as previously discussed.

Having considered the above list, we eliminate (1) since it is not nice to spit into the bath tub, and (4) is not possible because we have an officious guard on our barrier. Se we are left with (2), (3) and (5). Let us see what our network looks like now (Figure 26.4). The total duration of the operation or programme is now 43.45 minutes, a saving of seven minutes or over 13% for no additional effort. All we did was to resequence the activities. If we moved the wash basin near the shower and adopted the 'brush your teeth while you shower' routine, we could save

Figure 26.3

Figure 26.3

another three minutes, and if we bought a season ticket we would cut another three minutes off our time. It can be seen, therefore, that by a little careful planning we could well spend an extra 13 minutes in bed - all at no extra cost or effort.

If a saving of over 25% can be made on such a simple operation as getting up, it is easy to see what tremendous savings can be made when planning complex manufacturing or construction operations.

Let us now look at our latest network again. From A to G the activities are in the same sequence as on our original network. H and J (shave and boil water) are in parallel. H takes four minutes and J takes two. We therefore have two minutes float on activity J in relation to H. To get the total project duration we must, therefore, use the four minutes of H in our adding-up process, i.e. the longest duration of the parallel activities.

Similarly, activities L, M and Q are being carried out in parallel and we must, therefore, use M (fry eggs) with its duration of four minutes in our calculation. Activity L will, therefore, have one minute float while activity Q has two minutes float. It can be seen, therefore, that activities H, L and Q could all be delayed by their respective floats without affecting the overall programme. In practice, such a float is absorbed by extending the duration to match the parallel critical duration or left as a contingency for disasters. In our example it may well be prudent to increase the toast-making operation from three minutes to four by reducing the flame on the grill in order to minimize the risk of burning the bread!

Let us now look at another example. Supposing we decide to build a new room into the loft space of our house. We decide to coordinate the work ourselves because the actual building work will be carried out by a small jobbing builder, who has little idea of planning, while the drawings will be prepared by a freelance architect who is not concerned with the meaning of time. If the start of the programme is the brief to the architect and the end is the fitting of carpets, let us draw up a list of activities which we wish to monitor to ensure a speedy completion of the project. The list would be as follows:

Project Management Made Easy

Project Management Made Easy

What you need to know about… Project Management Made Easy! Project management consists of more than just a large building project and can encompass small projects as well. No matter what the size of your project, you need to have some sort of project management. How you manage your project has everything to do with its outcome.

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