Is Programlari 10.05

Is Programlari 10.05.2017

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CONSTRUCTION PROJECT PLANNING

“Planning is a decision making process performed in advance of

action which endeavors to design a desired future and effective

ways of bringing it about” (Ackoff, 1970).

“Trying to anticipate what will happen and devising ways of

achieving the set of objectives and targets” (Fryer, 1992).

Both definitions emphasize that in planning there are goals (objectives)

that are desired (or instructed or specified) to be realized in future, and

that planning is a process during which efforts and decisions are made to

achieve the goals at the desired time in the desired way.


The main objectives of a construction project are:

to complete the construction within the specified time (duration),

to complete it within the budget, (with a profit),

to complete it in compliance with technical and administrative

specifications.

Construction project consists of several work items (tasks /

jobs) to be completed at certain times during the execution of

the project. These work items are to be done in a sequence.

Some items cannot be started before some other items are not

completed.

Some items may be carried out at the same time


Depending upon the number of work items, their sizes and

scope, completion of a project will take a certain time, which is

called “project duration”.

Construction managers will have to plan their work in order to

be able to complete the project in time, within the budget and

by complying with the specifications and standards. To plan for

a construction project, the following four questions should be

taken into account.

What should be done? (activities=work items)

How should the activities be performed? (methods)

Who should perform each activity and with what means? (resources)

When should activities be performed? (sequence and timing)

PURPOSE OF PLANNING (WHY?)

The purpose of planning is to assist the manager to fulfill his primary function, namely, direction and control.

Direction can be subdivided into execution (or action planning) and coordination. Execution concerns the directing of the parties under the supervision of the

construction company in the implementation of the project components (work items). The essential elements of how, when and who are thus prepared for the execution of the construction project.

The second planning function is to coordinate and communicate with the many parties involved into the realization of a construction project, i.e. owner, designer, licensing authorities, subcontractors and suppliers, and numerous specialists and functionaries on site and in home office.

Project control encompasses control and forecasting. Control involves measuring and evaluating performance and the taking of corrective action when performance diverges from plans. To be effective, a control system must be modeled closely after planning system.


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PLANNING PROCESS (HOW?)

Process of planning comprises five phases

planning the planning process

information gathering

preparation of plans

information diffusion

evaluation of planning process

PLANNING THE PLANNING PROCESS:

Each project ought to be analyzed beforehand and

throughout its duration in respect of the features that make

it unique environmentally, technologically and

organizationally. Decisions made at this stage include:

effort and timing for each planning stage,

updating frequency,

planning horizons and level of detail,

degree of planning and control centralization

The planner further decides on

the selection of the information to be gathered,

the method of distribution,

on the scheduling techniques to be used.

INFORMATION GATHERING

The next phase, information gathering, may require considerable resources. The source material required for planning a typical construction project includes:

Contract documents

Drawings and specifications

Site and environmental conditions (investigate the site)

Construction technology

Internal and external resources (e.g. availability and cost) self-resources

list of possible subcontractors and suppliers

Productivity of labor and equipment

Goals and constrains dictated by top management, the client, and various external authorities regarding quality control, finance and law.

After construction has started, information regarding progress on site is also collected for control and forecasting purposes, with emphasis on resources consumed and goals achieved.

PREPARATION OF PLANS

In the third stage, working out the plans, decisions are made based on the evaluation of the collected information using techniques adapted to resource planning and scheduling (e.g. site layout, temporary facilities, flow diagrams and process charts, Gantt, Line of Balance (LOB), Critical Path Method (CPM) and Program Evaluation and Review Technique (PERT)) and their respective cost implications (e.g. cash flow, break-even and risk analysis).

1. Decide the level of detail for the project schedule

2. Decide the preliminary work breakdown structure (Activities=What?)

3. Decide construction methods and resources (Methods=How? and resources=Who?)

4. Decide project completion constraints

5. Divide project into milestones (Timing=When?)

6. Prepare milestone schedule (Master Time Plan)

7. Develop the detailed work breakdown

8. Collect scheduling information from subcontractors

9. Decide activities sequence and duration (CPM, When?)

10. Perform scheduling calculations (obtain construction schedules)


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INFORMATION DIFFUSION

The preparation of the plans is followed by information dissemination according to users’ needs. Information overload can be as harmful as a shortage. The planner must take a realistic, and to a certain degree psychological assessment, of what information is required by whom and in what format.

The evaluation of factors made during this phase includes: Functionaries receiving information (e.g. project manager, purchasing agent)

Scope of information (e.g. by entire projects or by area, comprehensive or selective)

Subjects (e.g. cost, procurement status)

Content (e.g. guidelines and goals, results and status, variances and reasons, analysis and calculations, assumptions and explanations, and remedy suggestions)

Level of detail (e.g. broad brush, very detailed)

Distribution frequency (e.g. weekly, monthly)

Format (e.g. textual, tabular, symbolic, graphical, pictorial)

Medium (e.g. visual – paper screen, auditory – take, telephone, direct meeting)

Accompanying activities (e.g. consulting, advising, training, negotiations, involving and promoting)

OUTPUT OF THE PLANNING PROJECT

As a result of the planning process, a complete schedule of the project is obtained. The major benefits that may be expected from the planning process and the project plan can be summarized as follows (Oberlender, 1993);

1. Finish the project on time

2. Continuous (uninterrupted) flow of work

3. Reduced amount of rework (least amount of changes)

4. Minimize confusion and misunderstandings

5. Increased knowledge of status of project by everyone

6. Meaningful and timely reports to management

7. Knowledge of scheduled times of key parts of the project

8. Knowledge of distribution of costs of the project

9. Responsibility/authority of people are defined

10. Clear understanding of who does what, when and how much

11. Integration of all work to ensure a quality project for the owner

12. You run the project instead of project running you

PROJECT SCHEDULING

Bar Charts (Gantt Charts):

Network Analysis Systems

Critical Path Method (CPM) – Deterministic

Program Evaluation and Review Technique (PERT) -- Probabilistic

BAR CHARTS (GANTT CHARTS)

Before CPM and PERT, the scheduling was performed by Bar

Charts.

Although, it is useful in some cases, it does not relate the

activities in a logical sequence.

A bar chart is generally organized so that all activities are

listed in a column at the left side of the diagram. A horizontal

time scale extends to the right of the list, with a line

corresponding to each activity in the list. A bar representing

the progress of each activity is drawn between its

corresponding scheduled start and finish times along its

horizontal line.

May be used in simple projects.


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While preparing the Chart,

Y axis is the ‘Activities’,

X axis is ‘Time’

Time is in Years/Months/Weeks.Time

Act

ivit

ies

2009 2010

Oct. Nov. Dec. Jan. Feb. Mar. Apr. May June

1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

Concrete

Works

Painting

Flooring


The boxes are filled according to the sequence and time of the

activities.

2009 2010

Oct. Nov. Dec. Jan. Feb. Mar. Apr. May June

1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

Excavation

Ftg. Conc.

Found. Walls

Cement pipe

Rubbles

Lean conc.

Walls

R/C Conc.

MODERN PROGRAMLAMA YÖNTEMLERİ

1958 yılının başında, “US – Navy Special Projects Office” adlı bir

büro kurularak planlama ve kontrol için yardımcı olabilecek çareler

araştırmaya başladılar. Çalışmalarını, kısa adı PERT olan, “Program

Evaluation Research Task” ismi ile açıkladılar. 1958 Şubatında, bu

grubun matematikçilerinden Dr. C.E. Clark, ilk defa teorik

çalışmalarını grafik gösteriliş haline getirerek “ok diyagramı” diye

anılan faaliyet şebekesini kurmuştur. Çalışmalar büyük gelişmeler

kaydederek, Temmuz 1958’ de, şimdiki PERT metodu diye

adlandırılan, “Program Evaluation and Review Technique” metodu

tamamlanmıştır .

Benzer çalışmalara A.B.D. Hava Kuvvetleri’nde de rastlanmaktadır.

1958 yılında, Du Pont de Nemours Company adlı kimyasal

yatırımlar yapan firma, çok büyük bir yatırımın planlanması ve

yürütülmesinde “Critical Path Method” kısa adıyla CPM, adı verilen

yeni bir sistem uygulamıştır. Bu metot sayesinde firma birkaç yıl

içinde milyonlarca dolar tasarruf sağlamayı başarmıştır.

NETWORK ANALYSIS SYSTEMS

They provide a comprehensive method for project planning,

scheduling and controlling.

Network analysis is a general title for the technique of defining and

coordinating work by a graphical diagram that shows work activities

and the interdependencies of activities.

Two techniques are widely used for scheduling:

Critical Path Method (CPM), which is deterministic;

Program Evaluation and Review Technique (PERT), which is probabilistic.


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CRITICAL PATH METHOD (CPM)The CPM was developed in 1956 by the DuPont Company, with Remington Rand as consultants, as a deterministic approach to scheduling. The CPM method is commonly used in the engineering and construction industry. In order for a project to be scheduled by CPM the followings have to be known:

Work breakdown structure of the project, so that each activity of the project is determined,

Predictions about the activity durations,

Logical relations between the activities

For project management the CPM is the most commonly used network analysis technique. The concept is simple, the computations only require basic arithmetic, and a large number of computer programs are available to automate the work required of CPM scheduling.

There are two basic methods of constructing CPM diagrams: the arrow diagram (activity on arrow)

the precedence diagram (activity on node).

Although both methods achieve the same results, most project managers prefer the precedence diagram because it does not require the use of dummy activities.

CRITICAL PATH METHOD (CPM) Activity: The performance of a task required to complete the project,

such as, design of foundations, review of design, procure steel contracts,

or form concrete columns. An activity requires time, cost, or both time

and cost.

Event : A notation to show the starting and ending points of an activity.

It is an instant in time horizon.

Network: A diagram to represent the relationship of activities to

complete the project. The network may be drawn as either an “arrow

diagram” or a “precedence diagram”.

CRITICAL PATH METHOD (CPM)

Duration (D): The estimated time required to perform an activity. The time should indicate all resources that are assigned to the activity

Early Start (ES): The earliest time an activity can be started.

Early Finish (EF): The earliest time an activity can be finished and is equal to the early start plus the duration

EF = ES + D

Late Finish (LF): The latest time an activity can be finished.

Late Start (LS) : The latest time an activity can be started without delaying the completion date of the project.


Total Float (TF) : The amount of time an activity may be delayed without delaying the completion date of the project.

TF=LETj-EETi-D

Free Float (FF) : The amount of time an activity may be delayed without delaying the early start time of the immediately following activity.

FF=EETj-EETi-D

Independent Float (IF) : The amount of time an activity may be delayed without delaying any other activity.

IF=EETj-LETi-D

where the subscript i represents the preceding event and the subscript j represents the following event.


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FLOATS

TIJ

TIJ

Total

Float

Free

Float

Independent

Float

EETi LETiEETj LETj


Critical Path : A series of interconnected activities through the network diagram, with each activity having zero, free and total float time. The critical path determines the minimum time to complete the project.

Dummy Activity : An activity (represented by a dotted line on the arrow network diagram) that indicates that any activity following the dummy cannot be started until the activity or activities preceding thedummy are completed. The dummy does not require any time and resource.

Classified as identity dummy and logic dummy.

Identity dummy: used to identify activities when two or more parallel independent activities have the same start and finish events.

Logic dummy: used to prevent the error in logic arising from chains of wholly or partly independent activities having a common event.

Identity dummy

Logic dummy

NETWORK CONSTRUCTION

Network diagramming techniques:

Activity on Arrow (AoA)

Activity on Node (AoN)

Summary of Denotations:


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RULES FOR NETWORK CONSTRUCTION

The arrows can be straight or broken.

Each activity is represented with an arrow.

An activity cannot be connected to the beginning of a

preceding activity.

RULES FOR NETWORK CONSTRUCTION

Activities can be subdivided into two or more arrows.

Each network must have a beginning and an end.

Only one activity can be defined between two nodes.

EXAMPLES (CPM)

1.K starts after A and B, L stars after B and C are completed.

2.K begins after A, L begins after A, B and M starts after B

and C

3.K begins after A, L begins after A, B and M starts after A,

B and C

4.Draw the network for the following activities:

P is the starting activity.

M and L starts simultaneously after P.

B and E start and end at the same time after M.

H follows L but M must be completed before it starts.

G and S are the last activities; G starts after E; S starts after H.


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EXAMPLES (CPM)

A, B, C are the initial activities.

D starts after A, G starts after C and E and F starts after B.

I starts after D, H starts after E.

In order to starts K, H, F and G should be completed.

J follows H and I.

J and K are the last activities of the network.

A

B

C

D

E

G

F

I

H

K

J

EXAMPLE:

In the following table you are given a set of activities, their durations and relationships between them.

You are required to;

a) Draw A-o-A

b) Draw A-o-N

c) Carry out CPM calculations on both of the diagrams to find the project duration and critical path.


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A-O-N


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A-O-N A-O-N

EXAMPLE

Carry out CPM calculations for the given A-o-A network below to find project

duration (days) and the critical path(s).


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IN THE CRITICAL PATH:

1.The early start and late start dates should be same at both

the nodes i and j.

(TiE = TiG , TJE = TjG)

2.The critical path starts at the first node and ends in the

last one. Every network has at least one critical path.

3.There may be more than one critical paths.

4.The time of the critical path is the time of the project.

5.The critical activities are the ones with zero total float.

(the total float can never be zero).

EXAMPLE (CPM)

Activity Preceding Activities Time (weeks)

A - 3

B - 4

C - 5

D A 8

E A, B 3

F C 5

EXAMPLE (CPM)

Activity Preceding Activities Time (months)

A - 5

B - 1

C A 2

D A 3

E A 2

F C 3

G D 4

H B, E 2

I H 1

J F, G, I 1

KRİTİK YOL YÖNTEMİ (CPM)

İşlem Adı Süresi Bağlı olduğu olay


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İşlem Adı Süresi (hafta) Bağlı olduğu olay

A. 1 -

B. 1 A

C. 2 B

D. 2 A

E. 2 D

F. 2 D

G. 3 E

H. 1 F

I. 1 G

J. 1 C,H

K. 1 E

L. 1 E

M. 1 L

N. 1 I, J, K, M

İşlem Adı Bağlı olduğu olay Süresi (hafta)

A - 8

B - 5

C - 6

D A 4

E A, B 6

F C 7

G A 5

H D, E, F 8

I C 9

J D, E, F 6

K G, H 4

L D, E, F 6

M I, J 4

Activity Dependencies Duration

A - 2

B - 2

C - 4

D - 8

E A, F 3

F B 4

G C, D, E 3

H D, G 2

I E 7

J G 6

İşlem

Adı

SüresiBağlı

olduğu olay

KRİTİK YOL YÖNTEMİ (CPM) - ÖRNEK

Aşağıda verilen bilgilerden yararlanarak

Projenin CPM serim modelini oluşturunuz.

Her bir işlem için verilen tij işlem sürelerini kullanarak projenin yatırım süresini (Ty) ve düğümlerin en erken ve en geç tamamlanma zamanlarını, işlemlerin bolluklarını ( SB/TB), kritik yol ya da kritik yolları, işlemlerin en erken ve en geç başlama zamanlarını (EBi j , ETi j , GBi j , GTi j ) bulunuz.

C, F ve I işlemleri beraber bitiş işlemleridir.

A, E ve H işlemleri başlangıç işlemleridir.

H işleminden sonra J, G ve I işlemleri başlar.

F işlemi B, D ve G işlemlerinden sonra başlar.

A, E ve J işlemlerinden sonra D işlemi başlar.

A işlemi B ve D işleminden öncedir.

C işlemi B ve D işleminden sonradır.

Kukla işlem sayısı iki tanedir.

İşlem Süre (Tij)

A 15 Gün

B 7 Gün

C 4 Gün

D 17 Gün

E 10 Gün

F 6 Gün

G 19 Gün

H 3 Gün

I 20 Gün

J 5 Gün

Is Programlari 10.05

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