Unit_2 Pengurusan Projek

8/13/2019 Unit_2 Pengurusan Projek

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UNIT 2: CHART AND PROJECT IMPLEMENTATION

SHCEDULE

INTRODUCTION

This unit will be discuss about the application of Bar Chart, Critical Path Method and

Microsoft Project Basic Operation in the project management.

2.1 BAR CHART METHOD

Schedule is a tool; it can be used to manage, coordinate, control and report.

Depending on the sophistication of the user, the schedule can take different forms.

There are a number of different forms of schedules that may be used, including written

schedules, bar graph, network schedules, and others.

Bar Chart also called a Gantt Chart is graphically the most simple of scheduling

methods. Bar Chart is one of the oldest scheduling technique and wide acceptance

because it is readily understood by almost every one. It is very easy to develop and

used, useful technique for a small project, task schedule can be graphically presented

on the time-scale but the main weakness is that Relationship that exists between the

tasks cannot be shown (no defined relationship). Figure 2.1(a) below shows Bar

Charts that graphically simple, easily to read and understood, and inexpensive to

produce.


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Example 2.1

From the Figure 2.1(b) below shows a simple bar graph schedule for a construction

project. Calculate scheduled and actual cumulative progress and plotted for the first

three weeks for physical progress of the project.

Notes:

The column headed Hours indicates the estimated number of labour-hours required

for each activity. The column Weight indicates the portion of the total project effort

accounted for by each activity. Notice that two horizontal blocks are provided opposite

each activity. The upper block (SCH) represents scheduled progress and the lower

block (ACT) is used to record actual progress as work proceeds. For each block, a barextends from starting to ending times. The number above each bar indicate

percentage of activity completion at each major time division.

The Normal Progress Curve or S-Curve is shown in Figure 2.1(c). As the curve

indicates, progress is slow at the beginning of a project as work is organized and

workers become familiar with work assignments and procedures. Thus, only about 15%

of the project is completed in the first 25% of the project time. After that, progress is

made at a rather constant rate until 85% of the work is completed at the end of 75% of

project time. Progress again slows as finishing work and project demobilization take

place.


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Figure 2.1(b)

Figure 2.1(c)


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Solution:

Step 1 : Calculate Weighting Factors

Example, Clearing and Stripping activity required 750 labour-hours of work, which

represent 4.7% of the 15,900 labour-hours required for the entire project.

(750 / 15900 ) x 100% = 4.7%

Step 2 : Calculate Scheduled Cumulative Progress and plotted

Cumu lat ive prog ress = Activ i ty Progress x Weight

Example calculation for the scheduled cumulative progress for the first three weeks of

the project as follow.

End of First Week

Progress Activity 1 = (0.20 x 4.7) = 0.9%

End of Second Week

Progress Activity 1 + Activity 2 + Activity 3

= (0.70 x 4.7) + (0.60 x 0.9) + (0.15 x 26.4) = 7.8%

End of Third Week


= (1.00 x 4.7) + (1.00 x 0.9) +(0.40 x 26.4) = 16.2%

Step 3 : Calculate Actual Cumulative Progress and plotted

End of First Week

Progress Activity 1 = (0.00 x 4.7) = 0.0%

End of Second Week


= (0.45 x 4.7) + (0.30 x 0.9) + (0.05 x 26.4) = 3.7%


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End of Third Week


= (1.00 x 4.7) + (1.00 x 0.9) + (1.00 x 26.4) = 16.2%

Step 4 : Draw Progress Curve

Frequently, cumulative progress curves for a project are superimposed on the project s

bar graph schedule as illustrated in Figure 2.1 (d).


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Exercise 2.1

Q1. Discuss about the effective of planning in construction management.

Q2. From the Table 2.1(a) below shows that small project activities.i. Draw the bar chart using graph paper.

ii. Try to track Schedule vs Actual for physical progress of the project

No. List of activities SchedulePeriod (Week)

Successor Actual Period (Week)

1 Setting Out & Excavation 3 2 4

2 Footing 2 3 2

3 Ground Beam 2 4,5 2

4 Slab 1 - 1

5 Column 3 6 1

6 Roof Beam 1 7,8 0

7 Brick Wall 7 - 0

8 M & E 7 9 0

9 Building Envelope 2 10 0

10 Ark. Finishing 3 - 0

Table 2.1(a)


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2.2 CRITICAL PATH METHOD (CPM)

2.2.1 LOGICAL RELATIONSHIP OF PROJECT ACTIVITIES

Understand the order of how the job to be accomplished in the field. The planner must

understand how various activities of the project related to each other in term of their

logical sequence. Example preparing formwork before reinforcement could be place &

than pouring concrete.

2.2.2 PREDECESSORS AND SUCCESSORS

The project network indicates the order in which activities may be performed. From

the Figure 2.2 (c), activity A is a Predecessor of activity B and activity B is a

successors of activity A.


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From the Figure 2.2 (d) :, Activity D has predecessors A, B & C. Only one activity is

allowed between two verticles; dummy activities may be defined if necessary (with

zero duration). Activities (3,5) and (4,5) are dummy activities with zero duration

Figure 2.2(d) : Dummy activities

In this module there are two type of network methods. There is Precedence Diagram

Method (PDM) and Arrow Diagram Method (ADM) but only Arrow Diagram Method

(ADM) will be discuss in detail for this unit.


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2.2.3 PRECEDENCE DIAGRAM METHOD (PDM)

Precedence Diagram Method (PDM) also known as Activity On Node (AON). PDM

activity is place on the node. The arrow used to connect between project task to showtheir logical relationship. From the Figure 2.2 (e) shows that structure of PDM diagram

for pad footing.

Figure 2.2(e)

See the example below, Table 2.2 (a) shows list of tasks, predecessor and duration ofproject. Figure 2.2 (f) is a network diagram using PDM. The diagram must draw from

start until end of activity.

Figure 2.2 (f)

bzzz


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Task Predecessor Duration

A none 5

B A 3

C none 3

D B 2

E B,C 4

F D 4

G D 2

H E 8

I A 5

J F,G,H 3

Table 2.2 (a)

2.2.4 ARROW DIAGRAM METHOD (ADM)

Arrow Diagram Method (ADM) also known as Activity on Arrow (AOA. In arrow diagram

project task or activities are represented by the arrow and connected by the node to

express their logical relationship. Each activity as illustrated in Figure 2.2 (g) must start

and terminate at an event (represent by a circle). Events are numbered for identification

purposes and event numbers are also utilized to identify activities on the diagram.

Thus activity 5-6 refers to the activity starting at event 5 and ending at event 6.

Following are formula time, must to calculate from start activity until end. From the

calculation, Latest Time of Finish Event (LF) for last activity is actually a total project

period.

i. ES is the Earliest Time of Start Event

EF = ES + Duratio n

ii. LS is the Latest Time of Start Event

LS = LF Duration


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iii. EF is the Earliest Time of Finish Event

iv. LF is the Latest Time of Finish Event

v. Activity duration (D) is the time to complete an activity

Figure 2.2 (g): Arrow diagram notation

Figure 2.2 (h) and Figure 2.2 (i) shows a simple network diagram for a constructionproject. As mentioned earlier, the diagram graphically indicates the relationships

between activities. Activities progress in the direction shown by the arrows. Good

diagramming practice requires that diagrams present a clear picture of the project logic

and generally flow from left to right. Arrows should not point backward, although they

may point straight up or down.

Notice the dashed arrow in Figure 2.2 (h) and Figure 2.2 (i). This is called dummy

activity or simply a dummy . Dummies are used to impose logic constraints and prevent

duplication of activity numbers. They do not represent any work and, hence, always

have a duration of zero.


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Figure 2.2 (h): Arrow Diagram Method (ADM)

Figure 2.2 (i) : Arrow Diagram Method (ADM)


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Task Predecessor Duration

A none 5

B A 3

C none 3

D B 2

E B,C 4

F D 4

G D 2

H E 8

I A 5

J F,G,H 3

Table 2.2 (b)

Example 2.2

From the Table 2.2 (c) and Figure 2.2 (j) below ;

i. Calculate ES,EF,LS,LF from the project activities.ii. Determine critical line

iii. Determine project period

Bil List of activities completed period

(Week)

1 Site Clearing 4

2 Setting Out 3

3 Piling 2

4 Pile Cap & stump 2

5 Ground Beam 4

6 Slab 2

7 Column 3

8 Roof Beam 4

Table 2.2 (c)


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Figure 2.2 (j) : Arrow Diagram Method (ADM)

Solution:

Step 1: Calculate ES,EF (forward pass)

Forward Pass a process to find the earliest start time for all activities.

Site Clearing work

Node 1 & 2

Start ES at first node with 0, ES1=0

Calculate EF use this formula, EF = ES + Duration

EF2 = ES1+Duration EF2 = 0+4 = 4

Setting Out work

Node 2 & 3

ES2 =4 (Start from Node 2,ES2=EF2)




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Piling work

Node 2 & 4




Dummy

Node 3 & 4




Now we have two arrow from node 2 and node 3 meet at node 4. From the Forward

Pass Theory, we must take the largest time of EF4 before continuing define ES4 for

Ground Beam work. Between 6 and 7, the largest must be 7, then fill 7 in the EF4 box.

Figure 2.2 (k)


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Continue calculate the ES and EF until finish (node 9) and fill in the table below.

Activity Duration ES EF LS LFSite Clearing 4 0 4

Setting Out 3 4 7

Piling 2 4 7

Pile Cap & Stump 2 4 11

GB 4 7 11

Slab 2 11 13

Col 3 11 14RB 4 14 18

Table 2.2 (c)

Step 2 : Calculate LS,LF (backward)

Backward a process to find latest finish time for all activities.

Roof Beam work

Node 9 & 8

Start LF 9 at last node with same value of EF 9=18

Calculate LS use this formula : LS = LF Duration

LF8 = LF 9 - Duration

EF 2 = 18-4 = 14


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Figure 2.2(l)

From the Backward Theory, if two arrow meet at one node, take the lowest time of LF

between the two value. Continue calculate the LS and LF until finish (from node 9 until

1) and fill in the table below.

Activity Duration ES EF LS LF

Site Clearing 4 0 4 0 4

Setting Out 3 4 7 4 7

Piling 2 4 7 4 7

Pile Cap & Stump 2 4 11 4 12

GB 4 7 11 7 11

Slab 2 11 13 12 14

Col 3 11 14 11 14

RB 4 14 18 14 18

Table 2.2 (d)


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Figure 2.2 (m)

Step 3: Determine critical line / critical path

Critical line / critical path are the longest paths of the planning from start to finish.

Usually the activity has same duration time start and finish. From the figure 2.2 (m), this

project critical for activities of site clearing, setting out, ground beam, column and roof

beam. The critical line is 1-2-3-4-5-8-9 with 18 week.

Step 4 : Determine project period

Total project period is 18 week


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Exercise 2.2

Q1. From the Table 2.2 (e) below shows list of project activity to construct the pad

footing at Surau Sek Keb Sri Gading.

i. Draw the logical network of the project

ii. Calculate ES,EF,LS,LF from the project activities.

iii. Determine critical line

iv. Determine project period

Nod List of activities Completed

period (Week)

1-2 Setting Out 2

2-4 Excavation 4

1-5 Order/prepare concrete material 1

1-3 Order/prepare bar reinforcement 3

3-4 Prepare Formwork 4

4-6 install bar reinforcement & formwork 2

5-6 Dummy -

6-7 Concrete 2

Table 2.2 (e)


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Q2. From the Table 2.2 (f) below shows list of small project activities those undertaken by a

contractor company.

i. Draw the logical network of the project

ii. Calculate ES,EF,LS,LF from the project activities.

iii. Determine critical line & project period

Bil List of activities Completed period

(Week)

1 1-2 4

2 1-3 1

3 1-6 12

4 2-4 10

5 3-5 8

6 4-6 8

7 5-6 8

8 5-7 4

9 6-8 8

10 7-8 7

Table 2.2 (f)

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