39
Planning & Controls Schedule 1/39 Project Planning and Scheduling Introduction In recent years, soaring construction costs and increased use of multiple prime contractors have caused many owners and developers to place increasing emphasis on project controls. Such controls play an integral role by serving as a means of protection to the owner and contractor in claim prevention and dispute resolution. The traditional methods available for planning and scheduling a construction project were basic and simple to produce. The bar chart developed Henry L. Gantt during world war I. was (and is) frequently used in simple jobs with few activities. The vertical column of a bar chart lists the major individual activities of the project: the horizontal column illustrates the time scale. A bar is then drawn on the graph representing a period of time for the commencement and completion of each particular activity. Each bar indicates when a particular task will begin and when work will be completed. ﻣﺸﺮو ع واﻟﺠﺪوﻟﺔ اﻟﺘﺨﻄﻴﻂ ﻣﻘﺪﻣﺔ وزﻳﺎدة اﻟﺒﻨﺎء ﺗﻜﺎﻟﻴﻒ وارﺗﻔﺎع، اﻷﺧﻴﺮة اﻟﺴﻨﻮات ﻓﻲ اﻟﺮﺋﻴﺴﻴﻴﻦ اﻟﻤﺘﻌﺎﻗﺪﻳﻦ اﺳﺘﺨﺪام ﻓﻲ ﺗﺴﺒﺒﺖ ﻣﺘﻌﺪدة ﻋﻠﻰ اﻟﺘﺮآﻴﺰ ﻟﺰﻳﺎدة واﻟﻤﻄﻮرﻳﻦ اﻟﻤﻼك ﻣﻦ آﺜﻴﺮ ﺗﺴﻴﻄﺮ اﻟﺘﻲ اﻟﻤﺸﺎرﻳﻊ ﻋﻠﻴﻬﺎ. ﻟﻌﺐ ﻣﻦ اﻟﻀﻮاﺑﻂ هﺬﻩ واﻟﻤﻘﺎو اﻟﻤﺎﻟﻚ ﻟﺤﻤﺎﻳﺔ وﺳﻴﻠﺔ ﺑﻮﺻﻔﻪ ﺑﻪ أﺳﺎﺳﻲ دور ل ﻓﻲ اﻟﻤﻨﺎزﻋﺎت وﺗﺴﻮﻳﺔ ﻟﻤﻨﻊ اﻟﻤﻄﺎﻟﺒﺔ. ﺑﻨﺎء ﻣﺸﺮوع وﺟﺪوﻟﺔ ﻟﻠﺘﺨﻄﻴﻂ اﻟﺘﻘﻠﻴﺪﻳﺔ اﻟﻄﺮق أﺳﺎﺳﻴﺔ ﻹﻧﺘﺎج وﺑﺴﻴﻄﺔ. اﻟﻤﺘﻘﺪﻣﺔ ﻏﺎﻧﺖ ل هﻨﺮي رﺳﻢ اﻟﻌﺎرﺿﺔ اﻟﻌﺎﻟﻤﻴﺔ اﻟﺤﺮب ﺧﻼل اﻻوﻟﻰ) ﻳﺰال وﻻ( ﻳﻜﺜﺮ اﻟﺘﻲ اﻷﻧﺸﻄﺔ ﻣﻦ ﻗﻠﻴﻞ ﻋﺪد ﻣﻊ ﺑﺴﻴﻄﺔ وﻇﺎﺋﻒ ﻓﻲ اﺳﺘﺨﺪاﻣﻬﺎ. ﺷﺮﻳﻂ ﻟﻠﺮﺳﻢ اﻟﺮأﺳﻲ اﻟﻌﻤﻮد اﻷﻧﺸﻄﺔ اﻟﻔﺮدﻳﺔ اﻟﻘﻮاﺋﻢ ﻟﻠﻤﺸﺮوع اﻟﺮﺋﻴﺴﻴﺔ: اﻟﻌﻤﻮد اﻟﻨﻄﺎق ﻳﻮﺿﺢ اﻷﻓﻘﻲ اﻟﺰﻣﻨﻲ. اﻟﺬي اﻟﺒﻴﺎﻧﻲ اﻟﺮﺳﻢ ﻋﻠﻰ ﺗﻌﺎدل ﺛﻢ ﺑﺎر وﻗﺎل ﻓﺘﺮة ﻳﻤﺜﻞ ﻧﺸﺎط آﻞ ﻣﻦ واﻻﻧﺘﻬﺎء ﻟﺒﺪء زﻣﻨﻴﺔ. وﺗﺸﻴﺮ وﻣﺘﻰ ﻳﺒﺪأ ﻋﻨﺪﻣﺎ ﺳﻴﻤﺎ وﻻ اﻟﻤﻬﻤﺔ ﺷﺮﻳﻂ آﻞ ﺳﻴﺘﻢ اﻟﻌﻤﻞ ﻣﻦ اﻻﻧﺘﻬﺎء

Project Planning And Scheduling

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Page 1: Project  Planning And  Scheduling

Planning & Controls Schedule 1/39

Project Planning and Scheduling

Introduction

In recent years, soaring construction costs and increased use of

multiple prime contractors have caused many owners and developers to

place increasing emphasis on project controls. Such controls play an

integral role by serving as a means of protection to the owner and

contractor in claim prevention and dispute resolution.

The traditional methods available for planning and scheduling a

construction project were basic and simple to produce. The bar chart

developed Henry L. Gantt during world war I. was (and is) frequently

used in simple jobs with few activities. The vertical column of a bar

chart lists the major individual activities of the project: the horizontal

column illustrates the time scale. A bar is then drawn on the graph

representing a period of time for the commencement and completion of

each particular activity. Each bar indicates when a particular task will

begin and when work will be completed.

التخطيط والجدولة عمشرو

مقدمة

في السنوات األخيرة ، وارتفاع تكاليف البناء وزيادة

متعددة تسببت في استخدام المتعاقدين الرئيسيين

آثير من المالك والمطورين لزيادة الترآيز على

هذه الضوابط من لعب . عليها المشاريع التي تسيطر

ل دور أساسي به بوصفه وسيلة لحماية المالك والمقاو

.المطالبة لمنع وتسوية المنازعات في

أساسية الطرق التقليدية للتخطيط وجدولة مشروع بناء

العارضة رسم هنري ل غانت المتقدمة . وبسيطة إلنتاج

التي يكثر ) وال يزال(االولى خالل الحرب العالمية

.استخدامها في وظائف بسيطة مع عدد قليل من األنشطة

القوائم الفردية األنشطة العمود الرأسي للرسم شريط

األفقي يوضح النطاق العمود: الرئيسية للمشروع

وقال بار ثم تعادل على الرسم البياني الذي . الزمني

وتشير . زمنية لبدء واالنتهاء من آل نشاط يمثل فترة

سيتم آل شريط المهمة وال سيما عندما يبدأ ومتى

االنتهاء من العمل

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Planning & Controls Schedule 2/39

The simplicity and graphic control effectiveness of the chart

have led to its wild acceptance as an effective planning and scheduling

device for certain projects. However, it cannot demonstrate the

interrelationship between tasks. Furthermore, the inherent limitations

and simplicity of a bar chart reduce its effectiveness in projects

involving a large number of varied activities. These drawbacks have led

to the development of a more complex approach – network planning –

which can incorporate a wild variety of activities and graphically depict

their interrelationship.

The inherent limitation of the bar chart prompted the use of more detailed scheduling methods. Network scheduling was developed in 1957 by E.I. DuPont de Nemours, Inc., in association with Remington Rand and was known as the Critical path Method (CPM). In the past few years in has taken on functions beyond the original concepts of time control and can now be used as a method of cost and manpower forecasting and control. These functions may, in fact, be beneficial in claim analysis. However, since many claims deal with damages caused by delays beyond planned project completion dates, this chapter focuses on the time aspect.

The principle function of a network schedule is to forecast the amount of time required from job start to job completion. As conditions change, a schedule can be utilized by project personnel to guide their decisions to achieve their goals.

بةبساطة وفعالية الرقا البياني للرسم وأدت إلى قبول البرية بوصفه وسيلة فعالة للتخطيط وجدولة

ومع ذلك ، ال يمكن أن تبرهن . المشاريع وسيلة لبعضعالوة على. على العالقة المتبادلة بين المهام ذلك ،

فإن القيود المتأصلة وبساطته حانة رسم الحد من ير من تنطوي على عدد آب فعاليتها في المشاريع التي

هذه العيوب التي أدت إلى وضع نهج . األنشطة المتنوعة والتي يمكن أن -- شبكة التخطيط --تعقيدا أآثر

وصف تتضمن مجموعة من األنشطة البرية وبيانيا .ترابطها

المتأصلة في الحد من المحامين ودفع رسم استخدام شبكة . تفصيال عن الجداول الزمنية أساليب أآثر

دو بونت دي .E.I من قبل1957 في عام الجدولة وضعتNemours المحدودة ، بالتعاون مع ريمنجتن راند وآان

أللف(يعرف طريقة المسار الحرج في السنوات ). ظهور القليلة الماضية اتخذت في وظائف خارج مفاهيم الوقت

ويمكن اآلن أن تستخدم آوسيلة من وسائل األصلي ،هذه. والمراقبةوتكاليف اليد العاملة والتنبؤ

المهام في الواقع قد يكون مفيدا في المطالبة ولكن بما أن العديد من. التحليل المطالبات من

التعامل مع األضرار الناجمة عن التأخير وراء المشروع ، فإن هذا الفصل التخطيط لمواعيد إنجاز

.يرآز على الجانب الوقتتنبؤ الجدول الزمني لل والمهمة الرئيسية للشبكة

وقتا طويال من العمل المطلوب لبدء العمل على وعندما. االنتهاء تتغير الظروف ، جدوال زمنيا يمكن

استخدامها من قبل العاملين في المشروع لتوجيه .قرارات لتحقيق أهدافها

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Planning & Controls Schedule 3/39

The development of a network usually starts with the

identification of the necessary work items to be accomplished.

Estimates should then be made as to the duration and sequence of the

items (or activities). When all these factors have been estimated, a

schedule can be calculated.

NETWORK SCHEULING

Networks scheduling has evolved into two primary methods of

representation. These methods are known as the “I – J” method (also

called the traditional CPM or activity – on – arrow method) and the

precedence method (or activity – on – node). The primary difference

between the methods is that I- J defined the activity as an arrow

between two numbered nodes (that is, the “I” node and the “J” node):

precedence defines the activity on the node. Examples follow showing

both methods, with accompanying graphic illustrations. Figure 4-1 and

Tables 4-1 and 4-2 illustrate I-J, while figure 4-2 and tables 4-3 and 4-4

illustrate precedence.

تحديد ما يلزم من تطوير شبكة وعادة ما يبدأ في

غي بعد وتقدر وينب. بنود العمل الذي يتعين إنجازهعندما ). أو األنشطة(وتسلسل البنود ذلك قدم لمدة

تكون جميع هذه العوامل وقدر ، وجدوال زمنيا.عن طريق شبكة التخطيط .ويمكن حساب

ة التخطيطشبك الجدول الزمني لتطور شبكات رئيسيين أساليب

" ياء--األول "هذه الطرق المعروفة باسم . التمثيللف ظهوروتسمى أيضا أل(طريقة --التقليدية أو نشاط

أو النشاط(واألسبقية طريقة ) طريقة السهم--على -- والفرق الرئيسي بين األساليب هو أن ). العقدة --العقد بين األول يعرف ياء النشاط سهما وبلغ عدد

يحدد ) : العقدة" ياء"العقدة و " أنا"أي (طرفين لتي تبين آل من األمثلة ا. العقدة األسبقية على نشاط .من اتباع األساليب ، وترفق بها بيانية توضيحية

، في حين أن IJ جداول توضح2-4 و 1-4 و 1-4الرقم .األسبقيةل جداو4-4 و -4 و 2-4الرقم .

Page 4: Project  Planning And  Scheduling

Planning & Controls Schedule 4/39

Critical path (I – J) method

The I – J method, or CPM, is used by many firms, although it

usually increases the size of the network due to the necessity of adding

“dummy” activities to represent restraining relationship. In CPM, the

two numbered nodes represent starting and finishing events, which

define the limits of the activity. By definition in CPM, node 110 in

figure 4-1 cannot “occur” until activities 108 – 110 and 107 – 109 are

completed.

Because of this requirement, CPM, often necessitates that a

given activity be broken into smaller components to illustrate that, in

reality, many activities can take place in parallel with their

predecessors. As

(I – J) طريقة المسار الحرج

طريقة ياء ، أو بألف ظهور ، وتستخدم --فإن األول ات ، على الرغم من أنه عادة الشرآ من قبل العديد من

ما يزيد من حجم الشبكة ونظرا لضرورة تنفيذ واضاف" في بألف ظهور . لتمثيل أنشطة تقييد العالقة" وهميةالبدء واالنتهاء من ، وهما وبلغ عدد الفروع تمثل في

حسب تعريفها . األحداث ، والتي تحدد حدود هذا النشاط ال يمكن ان 1- 4ل في الشك110ظهور ، العقدة في بألف

107 و 110 -- 108حتى األنشطة " تحدث" -- 109. وبسبب هذا الشرط ، أللف ظهور ، وغالبا ما يتطلب أن عناصر أصغر لتوضيح ذلك ، في يكون نشاط معين اقتحم

الواقع ، العديد من األنشطة التي يمكن أن تتم آأن. مع أسالفهم بالتوازي

Page 5: Project  Planning And  Scheduling

Planning & Controls Schedule 5/39

Figure 4-1 1-J Method

Shown in figure 4-1, some cables can be terminated (connected) before all the cable on the project has been pulled (installed).

The logic sequence shown in figure 4-1 describes a typical cable pulling operation wherein cable termination will start upon completion of 50 percent of the cable pulling (To simplify the illustration, the activities are assumed to be along the critical path – they have a total float value of zero). As illustrated by figure 4-1 in order to describe this particular sequence of activities, the CPM method requires four activities, plus two zero duration “dummy” activities to show restraints. The concept of the dummy or restraint for performance, inserted to sequence a particular task to more than one logical successor.

، فإن بعض الكابالت ويمكن إنهاؤها 1-4ي الشكل ف

المشروع قد سحبت قبل جميع الكابالت على) عالقة(

.(ترآيب(

يصف نموذجي آبل 1-4منطق التسلسل المبين في الشكل

الكابالت فيها إنهاء العملية ستبدأ عند االنتهاء سحب

ولتبسيط المثال ، ( في المئة من سحب الكابالت50من

نشطة التي يفترض أن تكون على طول المسار فإن األ

آما ). مجموعه تعويم قيمة صفر لديها ما--الحرج

لوصف هذا على وجه الخصوص سلسلة 1-4يتبين من الشكل

األنشطة ، ويتطلب طريقة الكلفة بألف ظهور أربع من

TIME DURATION

10 10 10

1110 11

PULL CABLE

FIRST 50 %

ACTIVITY

PULL CABLE

LAST 50 %

TERMINATE CABLE

FIRST 50%

TERMINATE CABLE LAST 50%

5

DUMMY

ACTIVITY DESCRIPTIO

NODE

Activity number

Page 6: Project  Planning And  Scheduling

Planning & Controls Schedule 6/39

The principal quantities calculated by CPM are the early start,

late start, early finish, late finish, and total float (or slack). The early

start date is the earliest possible time a given activity can start, and is

based on the completion of all preceding activities. The late start date is

the latest allowable time a given activity can start and not delay project

completion. (The definitions for early and late finish dates are similar,

except that the word “finish” is substituted for the word “start”). Total

float, or slack, is the “spare time” available along any given sequence

of activities and is calculated by subtracting the early start (or finish) of

an activities from its late start (or finish). If an activity late start is equal

to its early start, no spare time is available. The activity is, therefore, on

the critical path, which is the longest time sequence required for project

completion. If an activity is late, it has negative total float and may

delay project completion, unless schedule adjustments are made.

If the network schedule includes a large number of activities, it

may be computerized. Table 4-1 illustrates how the activities shown in

figure

إلظهار " وهمية" األنشطة ، والمدة الصفر زائد اثنين

ط النفس لدمية أو األداء مفهوم من ضب. أنشطة القيود

سلسلة خاصة لهذه المهمة أآثر من ، وتضاف إلى

المنطقي الخلف

حساب الكلفة بألف ظهور هي البدء الرئيسيةآميات

مبكر ، المبكر ، والتأخر في بدء واالنتهاء في وقت

). أو الرآود(والتأخر في النهاية ، وطرح ما مجموعه

وقت ممكن للبدء في أحد أقرب تاريخ البدء المبكر هو

نشاط معين ، ويقوم على استكمال جميع األنشطة

التأخر في بدء التاريخ هو أحدث الوقت .السابقة

إنجاز المسموح نشاط معين ال يمكن أن تبدأ وتأخير

التعاريف المبكر والتأخر في مواعيد . (المشاريع

محل آلمة " النهاية" االنتهاء مماثلة ، إال أن آلمة

" الفراغ" مجموع تعويم ، أو الرآود ، هو ").البدء"

أي تسلسل األنشطة ويحسب بطرح البداية المتاحة على

أو ) من أنشطة من التأخر في بدء) أو انهاء(المبكرة

إذا آان التأخر في بدء نشاط ما يساوي يبدأ ). اقفال

النشاط ، ومن . الفراغ في وقت مبكر ، لم يتوفر وقت

، الذي هو أطول من الوقت ثم فإن على المسار الحرج

إذا آان النشاط في . لتسلسل إنجاز المشروع الالزم

قد تؤخر وقت متأخر ، فقد بلغ مجموع سلبية وتعويم

.استكمال المشروع ، ما لم يتم تعديل الجدول الزمني

الزمني لشبكة تضم عددا آبيرا من إذا آان الجدول

1-4ويوضح الجدول . األنشطة ، فقد يكون الحاسوب

آيفية أنشطة مبين في الشكل

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Planning & Controls Schedule 7/39

Table 4-1 I-J computer print – out

Activity Description

Dur

atio

n

Early

starts

Early

finish

Late

start

Late

finish

Tota

l

float

105-107 Pull cable first 50% 5 4 Feb 8 Feb 4 Feb 8 Feb 0

107-108 Dummy 0 9 Feb 8 Feb 8 Feb 8 Feb 0

107-109 Pull cable Last 50% 5 11 Feb 15 Feb 11 Feb 15 Feb 0

108-110 Terminate cable 5 11 Feb 15 Feb 11 Feb 15 Feb 0

109-110 Dummy 0 15 Feb 15 Feb 15 Feb 15 Feb 0

110-112 Terminate Cable Last 50 % 5 18 Feb 22 Feb 18 Feb 22 Feb 0

4-1 would be printed out by computer. Assuming an early start data of February 4, 1980 the cables will all be pulled and terminated by February 22, 1980, or fifteen working days later. A timescale representation of the CPM network is shown in Table 4-2. As shown in Tables 4-1and 4-2, the week of 11 February 1980 has both a cable pulling and termination operation scheduled.

Many available computerized schedules contain software packages that also calculate other quantities. Such as free float or range. These quantities may be useful in certain applications. But their primary uses relate to the project schedulers. Consequently, they will not be discussed here. If the reader wishes more information on these quantities, any advanced text on CPM should provide a through treatment.

على افتراض أن تبدأ .سوف تطبع بها الكمبيوتر 4-1

الكابالت 1980 فبراير 4في وقت مبكر من البيانات ، أو خمسة 1980 فبراير 22جميع وأنهت وسوف يتم سحب

وهناك جدول زمني. عشر يوم عمل في وقت الحق للتمثيل آما هو مبين في . 2-4د في الجدول بألف ظهور شبكة ير

1 - 4الجداول and 4-2، 1980 فبراير 11واسبوع من قامت آل من آابل وإنهاء عملية االنسحاب في الموعد

.المقررتتوفر العديد من الجداول تحتوي على برامج الحاسوب مثل التعويم . الكميات مجموعات أخرى أيضا في حساب

ات قد تكون مفيدة في بعض هذه الكمي. الحر أو طائفة

Page 8: Project  Planning And  Scheduling

Planning & Controls Schedule 8/39

NETWORK SCHEDULING

Figure 4-2 precedence method.

Precedence method

To illustrate the basic difference between CPM and precedence, the sane sequence described above will be shown in precedence format in figure 4-2 and Table 4-3 and 4-4. As can be seen, the precedence format requires only two activities to describe the same sequence of events that requires six activities (in clouding dummies) in the CPM format. The primary difference between the sample computer listing (as shown in Tables 4-1 and 4-3) lies in the last column in Table 4-3 entitled. “Follower, Lead / Lag”. This column provides the means for sequencing the activities as well as providing lead / lag relationship.

إال أن أول ما تتصل يستخدم المشروع .التطبيقاتونتيجة لذلك ، لن يتم مناقشتها هنا. المنظمون إذا .

آان القارئ ترغب في مزيد من المعلومات عن هذه بألف ظهور النص الكمية ، أي متقدمة على الكلفة

.ينبغي أن توفر من خالل العالج

قة األسبقيةطري

لتوضيح الفرق األساسي بين بألف ظهور ، واألسبقية ،

التسلسل المبين أعاله سوف تظهر في شكل سابقة وعاقل

يمكن أن يرى آما. 4-4 و 3-4 والجدول 2-4في الشكل

، وشكل سابقة تتطلب اثنين فقط لوصف أنشطة ذات

Week of

Activity 4 Feb 11 Feb 18 Feb Pull Cable --------------

First 50% Pull Cable -------------- Last 50% Terminate Cable -------------- First 50% Terminate Cable -------------- Last 50%

121 122 TERMINATE CABLE 10

PULL CABLE 10

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The function of the lead / lag relationship is to allow the follower (or successor) activity to start before the completion of its predecessor something strictly forbidden in CPM. This ability for both activities to occur simultaneously is illustrated in the timescale representation in Table 4-4. This is accomplished by using four primary relationship: start – to (SS). Finish – to – finish (FF). finish – to – start (FS). Or overlap (OL).

Unless specifically started otherwise, every activity has a finish – to – start relationship, will all followers of finish – to – start zero (FS 0). Simply stated, it means that no follower can start until its predecessor is complete. The precedence method allows the scheduler to modify this inherent relationship.

FINISH – TO – START

As mentioned before, the finish – to – start relationship of FS 0 is the typical relationship. By changing the value of the relationship, say to FS 5, the start of the follower will now be delayed until five days after the finish of its predecessor. This relationship is illustrated in figure 4-3. (This type of relationship is often use to show lead time in a procurement sequence).

Activity / Day 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

1 ………

2 ……………..…

Figure 4-3

) في يعكر دمى(ستة أنشطة تسلسل األحداث التي تتطلب

والفرق الرئيسي بين الكمبيوتر . ظهور في الشكلأللف

-4 و 1-4آما هو مبين في الجداول (القائمة عينة من

. المعنون 3-4وتقع في العمود األخير في الجدول ) 3

هذا العمود توفر وسيلة ". التأخر/ أتباع ، الرصاص "

متخلفة العالقة/ توفير تؤدي لتسلسل األنشطة وآذلكتخلفةم/ وظيفة القيادة أو (العالقة السماح ألتباع

منعا لبدء نشاط قبل االنتهاء من سابقه في شيء يمنعهذه القدرة على حد سواء األنشطة في . باتا بألف ظهور

-4الجدول الزمني في التمثيل وقت واحد هو موضح فيويتم ذلك عن طريق استخدام أربعة العالقة األولية. 4

-- إلى --اء من االنته). س س( إلى --بداية :االنتهاء من). فرنك فرنسي(النهاية بدء --إلى --

الرتب األخرى(أو التداخل ). خ م( ). --له االنتهاء من وبدأ ما لم خالف ذلك ، آل نشاط

-- -- بدء العالقة ، وسوف ينتهي آل أتباع --إلى ببساطة ، فإن ذلك يعني أنه ). خ م 0) يبدأ من الصفر

أسبقية. دأ حتى أتباع سلفه آاملال يمكن أن تب يسمح المجدول طريقة لتغيير هذه العالقة المتأصلة

. النهاية –البداية

بدء عالقة -- إلى -- ذآر من قبل ، واالنتهاء من وآما

من خالل. خ م هو نمطية العالقة0 تغيير قيمة العالقة خ م ، بداية من أتباع سوف تتأخر حتى 5، ويقول ل

ن بعد خمسةاآل هذه . أيام من االنتهاء من سابقه وهذا النوع من. (3-4العالقة هو موضح في الشكل

العالقة ، وغالبا ما تستخدم الظهار الوقت في شراء )تسلسل الخالفة ).

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Planning & Controls Schedule 10/39

Figure 4-3

THE NETWORK SPECIFICATION

Table 4-4 precedence Timescale

Week Of

Activity 4 Feb 11 Feb 80 18 Feb

Pull Cable ----------------------------

Terminate Cable --------------------------

Activit

y

Description

Durati

on

Early

Start

Early

Finish

Late

Start

Late

Finish

Total

Float

Follows

Lead/Lag

121 Pull cable 10 4 Feb 15 Feb 4 Feb 15 Feb 0 121/SS 5

122

Terminate

cable

10 11 Feb 22 Feb 11 Feb 22 Feb 0

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Planning & Controls Schedule 11/39

START – TO – START

The start – to – start relationship was illustrated in our cable –

pulling example. The SS 5 meant that activity 122 could start five days

after the start of activity 121, as illustrated in Table 4-4.

FINISH – TO – FINISH

This relationship is used to relate the finishes of predecessor

and follower. An example is shown bellow. (The relationship shows

that activity 12 will finish two days after activity 11).

Activity / Day 1 2 3 4 5 6 7 8 9 10

11 .................... FF-2

12 ……..................

Figure 4-4

OVERLAP

The overlap relationship is actually a finish – to – start

relationship of negative value. In other words, a five – days overlap is

relationship is equivalent to an FS ( - 5). The overlap precisely what is

implies – the predecessor and follower overlap, or occur

simultaneously, for the specified number of days.

البداية – إلى --البداية

5. على سبيل المثال سحب-- العالقة يتضح في آابل يعني أن النشاط يمكن أن يبدأ بعد خمسة 122 فإن س

الجدول ، آما هو مبين في121أيام من بدء النشاط 4-4 .

النهاية– إلى --االنتهاء من

التشطيبات وأتباع هذه العالقة هي تستخدم لربطالعالقة . (على سبيل المثال يظهر الصوت عاليا. السلف

11 يومين من النشاط سينتهي بعد 12 يبين أن نشاط ).

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Planning & Controls Schedule 12/39

THE NETWORK SPECIFICATION

Why Use a Network

In the past, construction projects were often controlled by

means of bar charts showing relative positions, in time of various trades

and functions. Bar chart, however, are extremely limited in scope. They

cannot show critical interfaces between activities, nor can they

represent the dynamic nature of a project because they do not indicate

which activities are critical to the timely completion of the project. The

bar chart also several scheduling disadvantage because it can neither

adequately relate resource availability nor help management determine

where and how to predict problem areas.

The limitation of bar chart has been recognized. In Minmar

Builders, Inc..² the Armed Services Board of Appeals noted that:

Although two of the Appellant’s construction schedules

were introduced in evidence …. Neither was anything

more a bar chart shown the duration and projected

calendar dates for the performance of the contractual

tasks. Since no interrelationship was shown as between the

tasks the chart cannot show what project activities were

dependent on prior performance…. Much less whether

overall project completion was thereby affected.

الشبكة المواصفات

لماذا يتم أستخدام الشبكة في الماضي ، ومشاريع البناء في آثير من األحيان شريط الخرائط التي تبين األوضاع وسيلة للسيطرة

.النسبية ، وذلك في وقت من مختلف المهن والوظائفال . للغايةشريط رسم ، مع ذلك ، يتم في نطاق محدود

الحرجة ، وال يمكن أن يمكن أن تظهر وصالت بين األنشطةيمثل الطابع الدينامي للمشروع ألنها ال تشير إلى الحاسمة في الوقت المناسب الستكمال األنشطة التي

العارضة آما رسم العديد من جدولة. المشروع الحرمان ألنه ال يمكن أن تتصل بتوافر الموارد على نحو آاف ،

تحديد مكان وآيفية التنبؤ وال تساعد على إدارة مشكلة المناطق

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A good network planning schedule is a valuable tool in the area

of construction claims.

…. It is a method admirably suited to the construction industry,

and it provides a far more useful and precise approach that the

conventional bar graphs and progress charts that previously

formatted the basis of construction planning and control.

Furthermore, it permits the ready evolution and comparison of

alternative works programs, construction methods, and types of

equipment. When the best plan has been prepared in this way,

the critical path diagram clearly indicates the site operation

that controls the smooth execution of the work. Finally, as

construction proceeds, the diagram provides the project

manager with precise information on the effects of each

variation or delay in the adopted plan. Thus enabling him to

identify the operations that require remedial action. {Reference

Omitted}³.

If an initial schedule has been prepared carefully and if

consistent periodic updating of progress and changing conditions are

made, the CPM network provides a reliable method of reconstructing

the project.

.

في بناء Minmar .الحد من شريط رسم تم االعتراف الخدمات المسلحة في مجلس االستئناف يالحظ ما ². شرآة : يلي

اثنين من المستأنف بناء الجداول في عرض ورغم أنالبياني الرسمال شيء آان أآثر ويبين.... األدلة

حانة مدة الجدول الزمني والمواعيد المتوقعة ألداء نظرا. المهام التعاقدية لعدم وآان الترابط بين

المهام خريطة تظهر ما ال يمكن ألنشطة مشاريع تعتمد ناهيك عن ما إذا آان الشاملة .... األداء السابق على

.إنجاز المشروع مما تتأثر

الزمني هو أداة قيمة في شبكة التخطيط الجيد للجدول

مجال البناء المطالبات

. البناء ، وأنها توفر هو أسلوب مؤهلة لصناعة ....اآلن أآثر فائدة ودقة النهج التقليدي شريط الرسوم والخرائط التي سبق ان تقدم بشكل أساس البيانية

ك ،وعالوة على ذل. البناء والتخطيط والمراقبة يسمح لالستعداد تطور البديلة والمقارنة بينها وتعمل أفضل . المعدات برامج وأساليب البناء ، وأنواع

عندما أعدت خطة في هذا الطريق ، والمسار الحرج رسم إلى موقع العملية التي تسيطر على بياني يشير بوضوح

وأخيرا ، وبناء العائدات. نحو سلس على تنفيذ العمل ر المشروع ويقدم معلومات دقيقة عن ، الرسم مدي

تأخير في الخطة اآلثار المترتبة على آل تباين أومما يتيح له التعرف على العمليات التي . المعتمدة

المرجع محذوف³. () عالجية تتطلب إجراءات

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Network scheduling illustrates a logical sequence for various

activities and delineates which strings of activities are critical to the

timely completion of the project. As the use of multiply prime

contractors and fast – track construction procedures have increased, the

potential for project delays has likewise increased. Furthermore, ever

increasing craft waged have provided owners with a real incentive to

utilize a method that will anticipate areas of project delay in order to

maintain manpower levels. Because a network schedule identifies

interface points between various trades. Potential delays can be

highlighted and required decision can be made that allow owners a

broader range of options.

THE NETWORK SPECIFICATION

A well – prepared and maintained schedule not only provides a

tool for identifying problem areas, it also provides a good record of job

progress, which can be used to prepare or defend a claim.

Many owners and contractors now recognize the potential

benefits of a network schedule such as CPM. The lead in this area has

been taken by agencies of the federal government, such as the veteran’s

administration. Which includes a CPM specification as a part of its

contract.

. إذا آانت أولية وأعد جدول زمني دقيق ، وإذا آان

حرز وتغير الظروف ، يتمشى تحديث دوري للتقدم الموسيلة يمكن فإن الكلفة بألف ظهور الشبكة يوفر

.التعويل عليها إلعادة المشروعلتسلسل منطقي لمختلف شبكة ويوضح الجدول الزمني

األنشطة والتي تحدد شروط من األنشطة الحاسمة في آما تضاعف استخدام . الستكمال المشروع الوقت المناسب

تتبع إجراءات--سريعة المتعاقدين الرئيسيين والبناء قد زادت ، فإن احتمال تأخر المشروع وارتفع

وعالوة على ذلك ، يتزايد. بالمثل باستمرار الحرف تشن قدمت مع أصحاب حقيقية لالستفادة من الحوافز

توقع المناطق تأخير المشروع من وسيلة من شأنها أنددألن شبكة يح. أجل المحافظة على مستويات العمالة

. الجدول الزمني لنقاط التفاعل بين مختلف الحرفوالمطلوب قرار يمكن التأخيرات المحتملة يمكن إبراز

ان تسمح لمالكي مجموعة أوسع من الخيارات

. الشبكة المواصفات

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The extent to which any project will rely on a network schedule

such as CPM, will be determined by the strength of the CPM

specification included in the contract bidding documents. A well –

written specification will attempt to answer the following questions:4

1- Who should prepare the schedule?

2- What method of scheduling should be used?

3- Who will review and approve the schedule?

4- Who should submit information?

5- What purpose is the schedule expected to fulfill?

6- How are time extensions determined?

7- Who owns float?

8- Must the schedule be given to the subcontractors?

9- What are the requirements for notice of delay?

Each of these issues is addressed in this section. The answers, in

all cases, are qualified by the thought that any cost for front – end work

that ultimately saves money in construction or eliminates a potential

claim is money well spent.

وعلى استعداد ليس فقط الحفاظ على --وهناك أيضا لتحديد المجاالت التي الجدول الزمني يوفر وسيلة

تنطوي على مشاآل ، آما أنها توفر فرص العمل الجيدة الذي يمكن أن يستخدم إلعداد دفاع أو سجل التقدم

.المطالبةاالعتراف الفوائد العديد من أصحاب والمقاولين اآلن

. المحتملة للشبكة مثل الجدول الزمني أللف ظهورالمجال قد اتخذت من قبل وآاالت الرائدة في هذا

تتضمن. تحادية ، مثل ادارة المخضرمالحكومة اال .مواصفات أللف ظهور آجزء من العقد

مشروع على شبكة جدول مثل المدى الذي سوف يعتمد أيبألف ظهور ، وسيتم تحديد قوام بألف ظهور للمواصفات --وهناك أيضا . في العقد وثائق المناقصة الواردة4: لتالية ا مواصفات خطية سيحاول اإلجابة عن األسئلة

من الذي ينبغي إعداد جدول زمني؟ -- 1 جدول زمني ينبغي أن تستخدم؟ ما هي طريقة لوضع -- 2

من الذي سيكون استعراض واعتماد جدول زمني؟ -- 3 من الذي ينبغي أن تقدم المعلومات؟ -- 4

الزمني المتوقع ما هو الغرض من ذلك هو الجدول -- 5 النجاز؟

تحديد وقت التمديد؟آيف يتم -- 6 يمتلك تعويم؟ من الذي -- 7

يجب أن يكون الجدول الزمني لمن الباطن؟ -- 8 متطلبات إشعار تأخير؟ ما هي -- 9

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Who should prepare the schedule

(For a matter of convenience throughout the remainder of this section a CPM schedule will be used. The text can apply to any other network schedule as well). The preparation of a CPM schedule often requires much painstaking effort and many coordination meetings. The owner is often in much better position to mandate attendance at these sessions and therefore is usually the party that initiates CPM preparation meetings. However, the owner may elect to prepare the project schedule independently.

If this is the case, it is likely that the owner feels his organization knows the total project scope best. An owner – prepared CPM would most likely include preferred trade or activity sequencing and milestone targets that satisfy owner needs. Also it would often include contingency time for possible changes. However, this approach can be troublesome. Often an owner – preferred activity or trade sequence may not be the most economical from the contractor’s point of view. The contractor may then file a claim to recover his extra costs.

An obvious method of recover this type of claim is to have the contractor prepare the project’s CPM schedule. Following preparation, it would then be submitted to the owner for review to determine whether all necessary milestones are being scheduled. Actual activity or trade sequencing, however, is left to the discretion of the contractor. A disadvantage to this type of schedule is that the contractors is not always knowledgeable about areas of potential change orders and may not include sufficient contingency time.

األجوبة ، في . آل هذه القضايا تعالج في هذا الباب جميع

--الحاالت ، مؤهلون من قبل أن أي تكلفة للجبهة يوفر المال في المطاف انانتهاء العمل في نهاية

البناء او يلغي احتمال المطالبة أموال أنفقت في .مكانها

الذي ينبغي أن يعد للجدول الزمني لالطالع على سبيل راحة طوال الفترة المتبقية من هذا (

نص يمكن . الباب وجود جدول زمني أللف ظهور ستستخدم). أيضاأن تنطبق على أي شبكة أخرى للجدول الزمني

وضع جدول زمني أللف ظهور آثير من األحيان يحتاج الى الكثير من الجهد المضني والعديد من اجتماعات

غالبا ما يكون المالك في موقع أفضل بكثير . التنسيقوالية لحضور هذه الدورات ، وبالتالي عادة ما يكون

ومع . الطرف الذي يبادر أللف ظهور إعداد االجتماعاتز للمالك أن ينتخب إلعداد الجدول الزمني ذلك ، يجو

. للمشروع مستقلإذا آان األمر آذلك ، فمن المرجح أن يشعر صاحب

مالك . منظمته يعرف اإلجمالية للمشروع في نطاق أفضل مستعدة أللف ظهور على األرجح يفضل تشمل التجارة --

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Although the CPM schedule should include input from all

parties involved, the preparation of this input often depends upon the

party with the requisites expertise. Many contractors do not have

personnel capable of fulfilling this obligation; consequently, they rely

upon out side consultants. Similarly, owners often find themselves in

this same predicament. Scheduling may be viewed by both of these

parties as an overhead / services function with little money – making

capability. Consequently little effort is expended in attempting to

develop his capability.

Recognizing these facts, owners often require the use of an out

side consultant to prepare the initial schedule – particularly if

governmental agency feels that the contractor lacks CPM expertise.

The veteran’s Administration, for example, has stated that in order “to

assist in the preparation of the project plan…… the contractor will

engage ….. a consultant who is skilled in ….. network techniques for

the construction project.5

The advantages of an independent consultant are obvious. The

truly independent consultant will feel no need to “protect” any party,

and, consequently, his analysis may be more objective and

straightforward. However, if all parities are truly committed to timely

completion in an economical fashion, either the owner or contractor

could design a good schedule, providing they possess the necessary

expertise.

أو النشاط تسلسل األهداف والمعالم التي تلبي آما أنها غالبا ما تتضمن من . احتياجات المالك

غير أن هذا النهج يمكن أن . الوقت لتغييرات محتملة يفضل تسلسل النشاط --وغالبا ما مالك . تكون مزعجة

التجاري أو قد ال يكون أآثر اقتصادا من المتعهد ويجوز للمتعاقد ثم يرفع دعوى السترداد . وجهة نظر

. التكاليف اإلضافية له

يقة استعادة هذا النوع من المطالبة واضح من طروعقب . لمقاول المشروع وإعداد جدول زمني أللف ظهور

واإلعداد لها ، وعندئذ تقدم لمالك للمراجعة لتحديد ما إذا آان آل ما يلزم من معالم يجري في الموعد

النشاط الفعلي أو التجارة تتابع ، مع ذلك . المقررساوئ هذا النوع من ومن م. ، هو يترك لتقدير المقاول

الجدول الزمني هو أن المتعاقدين ليس دائما معرفة المناطق التي يحتمل وتغيير أوامر قد ال تشمل ما

.يكفي من الوقت للطوارئ

على الرغم من الكلفة بألف ظهور الجدول الزمني

ينبغي أن تشمل مساهمات من جميع األطراف المعنية ، يتوقف على الطرف مع وإعداد هذه المدخالت آثيرا ما

عدد آبير من الموظفين قد ال تكون . متطلبات الخبرةقادرة على الوفاء بهذا االلتزام وبالتالي ، فإنها

وبالمثل ، فإن . تعتمد على الجانب خارج االستشاريينويمكن . مالكي آثيرا ما يجدون أنفسهم في نفس المأزقاألطراف االطالع على وضع جدول زمني من قبل آل من هذه

مما يجعل --عامة وخدمات وظيفة مع قليل من المال ونتيجة لجهد ضئيل أنفقت في محاولة لتطوير . القدرة . قدرته

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THE NETWORK SPECIFICATION

What Method Of Scheduling

Should be Used

Obviously, the more complex the job, the greater the benefit to be derived form the use of a CPM network. A relatively large project (such as nuclear power plant) or a project involving multi – phased occupancy (such as a hospital renovation) would be extremely difficult to coordinate and manage by using a bar chart. Conversely, the construction of a cinder block garage to be used only as a vehicle storage facility may not require the time and expense of a comprehensive CPM network. Generally, the choice of a network schedule over the bar chart is predicated on the dollar value of the project (and the amount and manner of control desired by an owner if he prepares the schedule).

Who Will Review and Approve

The schedule

The approval of the schedule will depend, in part, upon who

prepares the schedule. If the project is multi – prime in nature, with the

general contractor providing the scheduling service, it would be a goof

practice to receive agreement not only from the owner but also from the

other parties that the schedule was “forced” on them or that it was

unrealistic with respect to their particular work.

التسليم بهذه الحقائق ، وغالبا ما تتطلب من أصحاب -استخدام خارج جانب خبير استشاري إلعداد جدول أولي

ول وآالة حكومية وخاصة إذا آان يشعر بأن المقا-المخضرم إدارة ، على سبيل . بألف ظهور يفتقر الخبرة

للمساعدة في إعداد "المثال ، قد ذآر أنه من أجل ستشارك وهو خبير ........... خطة المشروع للمقاول

استشاري في

project.5شبكة تقنيات لبناء ..... رةاالمهاستشاري مستقل حقا ، ال . مزايا استشاري مستقل واضحة

أي طرف ، وبالتالي " حماية"عر بالحاجة إلى يشومع ذلك ، إذا . تحليله قد تكون أآثر موضوعية واضحة

آان آل تعادالت ملتزمة حقا في االنتهاء في الوقت المناسب بطريقة اقتصادية ، سواء من المالك أو المقاول يمكن وضع جدول زمني جيد ، وتوفير ما

.يملكون الخبرة الالزمة

المواصفاتالشبكة

ما هي طريقة لتحديد موعد

وينبغي استخدام

ومن الواضح ، أن هذه المهمة أآثر تعقيدا ، وآلما . زادت فائدة استخدام شكل من بألف ظهور الشبكة

) مثل محطة الطاقة النووية(وهناك مشروع آبير نسبيا

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Often contractor specifications will require submittal of an

interim schedule diagram for the initial phase of contract work (say 90

to 120 days) prior to submittal of the complete CPM network. For

example, the veteran’s administration states that:

…. After receipt of notice to proceed, the contractor shall

submit ….an interim arrow Diagram covering the following

project phases and / or activities:

1- Procurement…..

2- The activities to be accomplished during the first 120 work

days of the project.

3- Summary activities to properly indicate ….remaining work

areas cost, duration, and equipment delivery….6

This technique of utilizing an interim network can be useful

where the contractor is uncertain of how work will be sequenced later

in the construction project. It allows the owner to develop an accurate

CPM for the early phases of the project in an expedient manner; yet it

gives the contractor the flexibility to develop a better long – range plan

with more time to develop material lead times and subcontractor

arrangements.

شغل المبنى --، أو التي تنطوي على مشروع متعدد سيكون من الصعب ) مستشفى التجديدمثل(على مراحل

على . للغاية تنسيق وإدارة باستخدام شريط الخريطةالعكس من ذلك ، بناء آتلة من رماد المرآب ال يستخدم إال آوسيلة لتخزين قد ال تتطلب الوقت وحساب الكلفة

عموما ، واختيار شبكة جدول . بألف ظهور شبكة شاملةمة الدوالرية فوق العارضة مخطط يقوم على القي

ومقدار وطريقة الرقابة التي يرغب المالك (للمشروع ). في حال ويعد الجدول الزمني

الموافقة باستعراض و يقومونالذينمن

الجدول الزمني

الموافقة على الجدول الزمني سوف يعتمد ، في جزء . منه ، بناء على الجدول الزمني الذي يستعد فيه

رئيس في طبيعتها ، مع --المتعدد وإذا آان المشروع المقاول العام وضع جدول زمني لتقديم الخدمة ،

سيكون من الناحية العملية الستقبال األبله االتفاق ليس فقط من مالك وإنما أيضا من األطراف األخرى إلى

، أو أن عليهم انها غير " القسري"أن الجدول الزمني .على العملواقعية فيما يتعلق على وجه الخصوص

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Who Should Submit Information

The preparation of a CPM schedule will be enhanced by

complete scheduling information. Timely and accurate submittal of this

information essential. It is helpful to call conference of all parties to

help hummer out a schedule. If the information is to be submitted on

paper. It is good practice to set a deadline in the contract for its receipt,

party in charge of CPM preparation from claims arising from schedule

interference.

What purpose is the schedule

Expected to fulfill?

The CPM schedules are often used in determining manpower

requirements or form issuing progress payments. If the schedule is

expected to fulfill these functions, it should be clearly stated in the

specifications. These requirements introduce an additional element of

expertise into the scheduling function, which will affect the choice of

what party will prepare the schedule.

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How are time extensions

Determined

The determination of time extensions is an extremely important

question to resolve with respect to construction claims. If a CPM

network is in use, the owner will quite often require a contractor to

submit evidence in the from of a CPM network fragment of “fragnet”

to justify claims or additional time. For example, a contractor may need

to submit that protion or fragnet of the CPM schedule dealing

specifically with the installation activities of constructing the elevator

shafts in order to support a demand for additional time.

The U.S. General services administration, in its specification,

requires the following:

…. The impact of change orders to this contract shall be

included in the project schedule… as a part of his proposal

for each change order involving a request for a time

extension or otherwise, the contractor shall submit a

network diagram showing the detailed work involved in the

change and the impact on other work of the proposed

adjustment of the schedule.

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The intent of this requirement is not only to show the work

sequence the contractor feels has been affected, but also to provide

adequate notice in order to develop alternative work sequences to

mitigate any delay. If a contractor has sufficient expertise, this clause

can be beneficial to all parties. If not, the clause can create a blizzard of

paperwork that bears little relevance to actual project problems.

THE NETWORK SPECIFICATION

Who “Owns” float

This question, in conjunction with the previous one, forms the

crux of many delay claims. Ownership of float time is also one of the

most disputed and puzzling questions to resolve since its answer is

dependent upon who is asked the question. If a contract states that it is

the contractor’s responsibility to start all activities as close to the

respective early starts as possible, the implication is that the owner

owns the float. Similarly, if the contract states that a time extension will

be granted only for delays occurring along the critical path, the owner

is also the implied owner of float.

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However, even these types of statements often do not dissuade

contractors from seeking damages for delay despite the fact that these

delays, however troublesome, did not delay actual project completion.

A good granted only for delays that actually delay anticipated project

completion. In this way, the owner is the implied owner of the float, but

the contractor is able to use this float to his advantage. Rather than

crate adversary relationships on any project, it is a good practice to

recognize that float exists for the benefit of all participants. Judicious

use of the float arising from necessity creates a harmonious

atmosphere. Allowing a party whose function is in jeopardy to use

some float can only increase the desire to complete work in a timely

fashion.

Must the Schedule Be Given to

The Subcontractors

The answer to this question depends primarily on the

complexity of the subcontractor’s work. If the subcontractor is hired to

perform complex work such as an intricate electrical control system, or

to work in a congested area, it is wise to inform the subcontractor of his

requirements regarding a CPM schedule. Furthermore, this practice

gives the contractor and/or owner a defense against a potential claim by

giving the subcontractor an opportunity to comment ton the schedule.

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What are the requirements for

Notice of Delay

As mentioned previously, many owners will mandate use of a

CPM fragnet as evidence for justification of delay. As a further

requirement, submittal of this fragnet must occur within a specified

period of time – often twenty working day. This requirement should not

be considered unreasonable. A contractor nearly always submits

invoices within one month and, in a way, these fragnets are invoices for

extra time. Furthermore, by complying with the terms of this provision,

the contractor has a permanent record that can be used in a defense

should litigation occur.

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PITFALLS OF AMBIGUOUS

SCHEDULING SPECIFICATIONS

Often, through a lack of owner sophistication and/or an

underestimation of the project scope, a poorly written CMP

specification is included al most as an afterthought to the contract. In

many respects, this type of specification may be worse than no

specification at all. The following clause was used in a contract for

construction of a forty-story office building:

The contractor shall complete the work so as to give

beneficial occupancy and use to the owner in accordance

with a schedule which best suits the owner’s requirements

and which shall be mutually agreed upon prior to the start

of construction.

The vague language of this clause does not attempt to answer

the questions addressed previously. No mention is made of whether

networking techniques are to be used, who will prepare the schedule,

what specific functions the schedule with serve, how a delay will be

determined, or who owns any available float. Furthermore, it gives no

guidelines whatsoever as to the type of information the contractor is

obliged to furnish to meet the “owner’s requirements”. It appears to

give the owner an open ended argument in any case.

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In a situation such as this, it would be advantageous to the

contractor to prepare a CPM network on his own to submit as the

official project schedule. The contractor’s CPM network illustrates

good faith on the part of the contractor and provides a tool for

illustrating any delays that might occur. The owner would find it to his

advantage to thoroughly review the submitted CPM to ensure

compliance with the requirements. If any objection is to be raised, it

should be made promptly in writing. This would put the owner on

record as objecting to the contractor’s planned sequencing.

In addition, ambiguity in the specifications may lead to a

“laissez-faire” approach to scheduling. Experienced construction

people often tend to forego schedule projections in response to a “gut

feeling” that they may have concerning project status. This approach

leads to trouble where the schedule is ignored and the gut feeling is

inaccurate. By the time all parties realize the schedule had been

accurate all along but has not been followed, it is often too late to

recover the lost time. A tight, well – written specification will help to

define schedule responsibility and prevent costly completion delays.

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ANALYSIS OF THE SCHEDULE

Obviously, in order to prepare a claim (or conversely to defend

against a claim) the interpretation of the schedule becomes a very

important function. Because of its failure to show the relationship

between activities, a bar chart has proven inadequate for schedule

analysis.

A strong CPM that has been periodically updated serves as a

clear record of the job history. By reviewing the project records,

including the original project schedule submitted to and approved by

the owner, schedule adjustments, estimates, progress payments, daily

time reports, correspondence and memoranda, material or supply

deliveries, cost accounting records, and change order files, the job

history can be easily traced.

However, it must be remembered that the existence of a CPM

schedule does not automatically constitute proof of one’s claim. Of

primary necessity in CMP analysis is the determination of the

feasibility of the schedule. Illogical relationships, no matter how

unintentional, can severely damage a case. Likewise, car must be taken

to portray the truth of the project and not to disregard the facts. It must

therefore be emphasized that initial accurate CPM input can enhance

the validity of subsequent claim.

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The as- Planned versus the

As-Built Network

One of the principal tools of a scheduling analyst preparing for

a trial or arbitration is the use of charts or graphs depicting the project

“As planned” versus the project “As – Built.” The intent of these

networks is to show how external forces conspired to cause delay to

one’s client. The existence of a well – maintained project CPM

simplifies this task. If all information, such as actual start and

completion dates, change order work, and material procurement, is

recorded in the CPM, the task is reduced to summarizing the network in

a concise form and depicting it in a logical, uncluttered fashion.

The level of detail portrayed in the summary is a function of the

complexity of the project. However, in all cases, one should be mindful

of the fact that the simpler the chart, the easier it is for the judge, jury,

or arbitrator to comprehend it. This naturally increases the chance of

proving one’s point and winning the case.

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For example, an as – planned versus as – built schedule for a

nuclear power plant is usually a detailed and complex network drawing,

illustrating the versus interrelationship between job activities. The as –

planned portion of the drawing is often developed from the existing

project CPM through summarization of the activities. The as – built

portion can be developed from various sources, including the CPM and

project monthly reports.

This drawing (the as – planned versus as – built schedule),

through, is rather detailed may confuse a judge or arbitrator. In order to

facilities clearer representation of the critical path delays, a drawing

similar to the simplified because only in figure 4-5 is developed. The

drawing in figure 4-5 is tension of the judge or arbitrator is

immediately drawn to the delay that appears significant. The

explanations included in the notes in figure 4-5 are added to further

clarify the position.

Use of a chart such as this is highly recommended. The use of

one chart can simplify many pages of text. In fact, one well – conceived

chart could be the significant factors that influence the award of delay

damages to one’s client.

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Reconstruction of the project

With No CPM

Many construction supervisor tend to perceive scheduling as a

necessary evil. Being “result – oriented”, construction supervisor often

are uninterested in the details of an activity’s completion. Pressing day

– to – day commitment often obscure activity completion dates in their

mind unless they are immediately and dutifully recorded. Phrases like

“we completed that around the middle of last week” have been heard

by schedulers since the concept of CPM was developed and,

unfortunately, will probably continue to be heard for many years to

come.

As a result, even the best schedules often do not contain

complete information on activity completion dates. All is not lost,

however because most projects contain a wealth of supplemental

information that can be utilized to reconstruct the project. Most

contractors are required to submit daily time reports detailing the

number of men working and the tasks being performed. These

documents can be used to develop a “construction chronology” (figure

4-6). A chronology can summarize, by contractor, the daily work being

performed and can be used to determine not only activity completion

but logical sequencing.

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Figure 4-6

SOURCE

CODES PAGE ____ OF _____

CLAIM ANALYSIS CHRONOLOGY

Type work ___________________

Contractor ___________________ 1. gen. Contractor 4. Subcontractor 1

2. Arch. 5. subcontractor 23. Owner

DATE FLOOR AREA QUANTITY UNITE CODE DESCRIPTION No

3/3 5, 9, 11, 13 1 Day wall, taping finishing 4, 5, 8, 14 1 2 3 4/3 5, 9, 11, 13 4 Day wall, taping finishing 4, 5, 8, 14 4 5 6 4/4 5, 9, 11, 13 4 Day wall, taping finishing 4, 5, 8, 14 7 8 9 10 4/5 4, 5, 9 4 Day wall, taping 4, 5, 8, 14 11 12 13 4/6 9, 11, 13 4 Day wall, taping 4, 5, 8, 14 14 15 16 4/7 4, 9, 11, 13 1 Day wall, finishing 4, 5, 14, 19 17 18 19 4/26 11-22 2 Day wall, finishing 4, 5, 14, 19 20 21 22 4/30 14-22 2 Day wall, finishing 5, 10, 15, 17, 19 23 24 25 26 5/2 14-22 1 Day wall, finishing 5, 10, 15, 17, 19, LPL 27 28 29 5/3 14-22 1 Day wall, finishing 5, 10, 15, 17, 19 30 31 32 5/4 14-22 1 Day wall, LPL 5, 10, 15, 17, 19 33 34 35 36 37 38 39 40

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ANALYSIS OF THE SCHEDULER

For example, if an electrical contractor on a twenty – story

office building submits a claim for inefficiency based on increased

material handling, a chronology can help demonstrate the building

areas he worked on the second floor on Monday, the seventh on

Tuesday, the tenth on Wednesday, the fourth on Thursday, and the

sixteenth on Friday, chances are that his claim may be valid and may

merit further investigation.

A chronology can be equally effective to diffuse an argument. If

it can be shown from the chronology that the work followed an orderly

progression up the building the contractor’s claim for inefficiency may

be unjustified. Similarly, purchase orders, material receipt reports, or

bills of lading can be used to determine material delivery dates versus

contract requirements. Phone record and memoranda often address

delays encountered – whether the delays were caused by labor

disruption or interference from another party on the project. Monthly

payment requisitions may also give insight into the amount and type of

work accomplished in a given month. While these records are an

absolute necessity in the event of an incomplete CPM, they also

provide an excellent source of substantiation for the schedule. A case

can only be strengthened by backup documentation that supports data

obtained from the schedule.

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Another area of documentation that is a valuable aid in

adjusting the schedule is the shop drawing log. This document, usually

maintained by the architect / engineer, traces the history of all project

drawing and sample submittals. Examination of this log can determine

whether submittal or approval of any particular drawing or sample was

delayed beyond contract requirements. This information can then be

superimposed on the as – planned schedule to show the effects.

If no CPM is specified for the project, the development of an

“after the fact” as – planned network may or not serve to help one’s

client. It could then appear that the client was interested in a CPM

schedule not as a project control tool, but only as a device for claiming

damages. For example, in Chaney and James Company v. united

state,11a case involving a contractor’s claim for unreasonable delay by

the government, the united states court of claims declared, in part, that:

….. The work sequence shown was not used in estimating and

bidding the job since the original chart….was not in existence

until….the end of the project. Also, as the contractor’s project

manager admits, the sequence shown in the critical path was

not followed in performing the contract work (and the

contractor’s claim is disallowed)….

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In some cases, a bar chart can be converted into a network

schedule by examining such items as the contractor’s bid estimates,

contract documents, memos, and time sheets. This “created” schedule,

however, is only as good as the documentation from which it evolves.

The Adjusted As – planned

Schedule

In addition to as – planned and as – built schedules, preparation

of a claim or defense for a claim often requires the preparation of a

third type of chart, the “adjusted As planned schedule”. This is most

often used on a job when changes are a factor. The primary purpose

served by a document of this nature is to illustrate either (1) that the

particular change in question, while using project float, did not delay

project completion; or (2) the change in question so severely affected

the plan of the project that activities that were initially non – critical

eventually became the activities that delayed the project.

As mentioned previously, supplemental project documents such

as daily time reports, telephone records, and correspondence often

augment information already continued in the schedule.

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Legal recognition of CPM

Schedule

Courts have begun to emphasize the importance of CPM

scheduling. The detail and interfacing capabilities of CPM allow

identification of key elements of delay not possible with simple

scheduling techniques, such as bar charts.

The armed services Board of Contract Appeals in Minmar

Builders. Inc. 12 recognized the limitations of bar charts while noting

the value of CPM scheduling. The board stated that:

In short, the schedules were not prepared by the Critical

path Method (CPM) and hence are not probative as to

whether any particular activity or group of activities was on

the critical path or constituted the pacing element for the

project.

This is a very significant finding. If nothing else, it should serve

as a warning to contractors and owners alike that sophisticated

scheduling techniques are being viewed as the norm rather than the

exception. The initial expense for developing CPM expertise (or for

hiring an outside consultant) may pay dividends if a dispute arises.

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Another case illustrating the value of CPM is Blackhawk

heating and plumbing company. 13 where the General Services

administration board of contract appeals was asked to decide on a claim

for 403 days of delay. In the course of the job, the contractor submitted

a CPM which while never accepted, did present a logical and practical

method for project completion. As a result, the government retained a

consultant to prepare an as – built schedule as part of its defense. The

as – built schedule when compared with the contractor’s plan, helped to

determine that the contractor’s activities (HVAC duct work) were not

on the critical path. As a result, the time extension was defined.

A significant aspect of the Blackhawk decision can be found in

its implied answer to the question of who float time. By denying a time

extension because the activities were not on the critical path, it was

implied that the owner (the government) controlled the float on the

project.

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CONCLUSION

Network scheduling has been gaining much wider acceptance

in recent years. However, may contractors and owners still balk at the

implementation of a network schedule for a number of reason: cost,

lack of understanding, and / or resistance to new techniques. None of

these three arguments is sufficient reason not to use network scheduling

when compared with the potential savings offered by such a schedule.

A properly developed schedule provides an excellent method for

forecasting future problems, and should a dispute arise, the schedule

could be the single most valuable tool in presenting a claim or in

preparing a strong defense.

NOTES

1- J. Anthill, R. Wood head and R. wood head, critical path methods in construction practice. 2d ed. New York: Hohn wiley & Sons, 1970: J.O. Brien, CPM in construction Management. 2d ed., New Yourk: Mc Graw-Hill. 1971.

2- Minmar Builders. Inc., GSBCA 3430, 72-2 BCA 9.599.

3- American Sanitary sales Co. Inc New Jersey. No. A – 1939-79 (App. Div. 1978).

4- Paul J. Walstad, “The project schedule and the claim.”

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Construction claims 1977. seminar at Engineering News Record Conference and Exposition Management Co. Inc.

5- Section NAS of the United States Veteran’s Administration Specifications.

6- See Note.

7- Section 0117 of the United States General Services Administration Specifications.

8- See generally, sovereign construction Co. Ltd., ASBCA 17792, 75-1 BCA 11, 251: Dawson construction Co. Inc., GSBCA 3998, 75-2 BCA 11. 563.

9- See Note 3.

10- Tomas C. Peacock. “A Survey of Available Methods of Establishing specific Durations of Construction Delays – from Bar Charts to Network Analysis System. “Construction Claims. Practicing law Institute (1979).

11- Chaney and James Company v. United States. 421 F. 2d 728 (Ct. C1. 1970).

12- See Note 2.

13- Blackhawk Heating and plumbing Co. GSBCA 3432, 75-1 BCA 11, 261.