Importance Of Project Time Management Using PERT & CPM For Scheduling Projects

Research Questions

What is the importance of Project Time Management for Scheduling the Project through PERT & CPM?

Introduction

Project time management is very much important for scheduling the all the activities related with the project. It is more difficult job for project manager to manage a large scale based project which needs coordination of numerous activities. It is known that the management of project involves the activities of planning, co-ordination, monitoring control and review of the performance of number of inter-related tasks with limited resources. Apart from studying the inter-relations, the project manger has to know the consequences of deviations from the initial plan in order to take appropriate corrective measures on the effect of delay in one task on the other tasks. Project manager are compelled to look for dependable dynamic planning, scheduling, control and monitoring devices. Network techniques are primarily used in project management, particularly in dealing with non-repetitive operations.

Network techniques are nothing now, as most managers have been using such techniques in one form or the other in project management by calling them, ‘commonsense which is uncommon’ (Trietsch & Baker, 2012). Most managers face enormous increase in the complexity of their work, and face problems of uncertainty while tackling futuristic situations. The network specifically deals with these situations. Network techniques provide the help a manger needs, when he is defining the complex relationship that exists in ‘sequencing’ and ‘time’ between many jobs and planned elements of work. Thereafter, during the execution of the project, the inevitable slippages from planned schedule occur. Network analysis enables the project manager to determine the importance of these deviations by taking the most cost-effective measures after adequate monitoring, evaluation and control (Oberlender, 2014).

This study contains the importance and all the aspects of PERT/CPM for the time management of the project.

Research questions are considered to be useful in understanding the topic of the research in a much easy and well manner. The research question focus on the area of analysis which can help to gain the relevant and useful information according to the topic selected. The research questions for the current study are as follows:

What are the importance of PERT/CPM for scheduling the project?

What time is needed to complete the entire activities of the project?

What are the starts and end times or each activity?

Which critical activities needed to complete according to the schedule to meet the estimated time for the completion of project?

Relevance Value

Which critical path is best for the completion of all activities with minimum cost?

The advancing technological revolution of space age has brought an explosive growth of a new of planning and controlling techniques (Young, 2010). Much of the development work has done in defence sector, but construction, chemical and other industries have also played a crucial role. These techniques are network based planning and control procedures and known as PERT (Project Evaluation and Review Technique).

The requisites of PERT are important if the system is to be used effectively in Project Management. The project goal needs to be clearly and unambiguously identified; all the individual tasks in a given program need to be visualized in a logical manner, creating a work-break structure (Dinsmore & Cabanis-Brewin, 2011). These are put in a network flow diagram, which is comprised of events and activities; the duration of an activity, except in a time-scale network, is not presented by the length of the line. An activity succeeding an event cannot occur until all activities leading to all it is accomplished (Bielefeld, 2009).

Image 1

All activity paths need to be completed by appropriate events, and a description of each activity needs to be written above the arrow linking the events. Emphasis is laid on defining events and activities with precision so there is no difficulty in monitoring actual accomplishment (Ju & Xie, 2009).

Events and activities need to be sequenced in the network under a logical set of ground rules which allow the determination of the critical paths, and all constraints, and interdependencies need to be clearly shown in the diagram (Ash & Pittman, 2008). The numbering of events can be forward or backward, depending upon whether the network diagram begins from the starting point or the ending point.

Image 2

PERT network analysis consists of following steps:

Clearly defining the goal of the project.

Obtaining a work-break structure to set a individual jobs, and arranging them in a logical fashion

Estimating the job duration, making provisions for optimistic and pessimistic schedules.

Identifying the resource requirement constraints

Locating the schedule of dates for each activity by planning a detailed control structure

Preparing project control systems, and identifying the requirements of progress reports for different levels of management

Developing the critical path and slack times

Crashing the time-optimum cost levels on the basis of costs

Updating the network continuously by systematized methods

Monitoring, evaluating and reviewing the network continuously.

PERT

Image 3

PERT gives management ability to plan the best possible use of resources to achieve a given goal within the overall time and cost limitations. It enables the project executives to manage the a variety of programs, as opposed to repetitive production system; it helps the project manager to handle the uncertainties involved in programming where no standard time data are available; it utilizes the time network analysis as a base method of approach to determine the manpower, material, machinery and capital requirements (Onofri & Spagnuolo, 2014).

PERT is an effective mechanism for planning, scheduling and coordinating the different activities in project buying.

PERT enables the optimum utilization of the resources by their transfer from the slack to busy segments in the network in order to accomplish the stipulated goal. It is useful for pre-crisis planning and buying when the force majeur clauses are operative because the responsibilities to project executives are allocated well in advance to tackle such emergencies (Kim, Kim & Dong, 2014).

PERT is one of the most important techniques of scientific management in project planning with the minimum possible scheduling time and use of resources. Inefficiencies in personal loading can be removed by the proper use of slack activities; lead can be analyzed, thus expediting the work schedules (Dolabi, Afshar & Abbasnia, 2014).

PERT network reveals the interdependencies and problem areas which are not obvious or not well defined by the conventional methods. On the basis of three time estimates, the PERT network caters to the intricacies of uncertainties that confront the decision-makers.

The construction of PERT involves the identification of activities connecting to the necessary events of the system in a sequence which culminates in the completion of a project. The PERT network is flow plan consisting of the activities and events that must be completed to reach the goal of the program together with their interdependencies and inter-relations (Baradaran, Ghomi, Mobini & Hashemin, 2010). It shows, orderly, step by step, series of activities carried out in a logical sequence to reach the goal. The events from the foundation for describing the activities included in them events describe the beginning or the completion of one or more activities. The activities are the channels of flow of the network and the manager can control this flow of material, investment, expenses, human efforts, time spent, etc to achieve the final project goal (Sears, Sears & Clough, 2010).

Steps of PERT

Image 4

It is evident that delay in any of the activities on the critical path will delay the entire project. However, the activities for which positive slack time is available can be performed at a slower pace, thereby releasing the some of the resources for use in critical activities, provided the all activities are interchangeable (Kerzner, 2009). If the total duration of the project is to be reduced for some reason, the activities to be considered will be the ones on the critical path. The activities falling on the next longest path trace the subcritical path.

The most economic time with minimum cost is the only resource under consideration. Ensuring earliest project completion often means conscious and deliberate acceptance of inconvenience, higher cost and deviations from the established practices (Adegoke, 2011). The project management environment is never static and undergoes rapid changes. All efforts at planning, budgeting, scheduling and forecasting are directed at anticipating future outcomes based on the decision taken today. Since the future seldom turns out to be what was expected, there is a constant and urgent need to assess the projections and correct the commitment of resources. Management of costs in a project tries to achieve this objective by the deviations and providing the mid-course correction.

Methodology contains the detail research techniques to analyze the importance of PERT and CPM for scheduling the project. For this current research study application of the deductive approach is literally intrinsic which let the researcher perform the study more intrinsically. Evaluation of the information and the data collected in account of the primary research work, deductive research approach seems to be essentially bold (Al-Begain, Fiems & Knottenbelt, 2010). Application of descriptive design is literally helpful for this research particular research work. Application of both qualitative and quantitative approach of this research work is essential for this research work.

Research design helps in explaining the framework of the research topic that will help in selection of the collection and analysis pattern. During the process of data collection, a particular kind of approach is applied that helps in better description of the research design. Kinds of research design used in academic research pattern are exploratory, explanatory and descriptive. For this particular research work the researcher is going to seek for the necessary attributes from the different parts. At the same time the researcher does not. The extent of influence imparted by PERT and CPM for scheduling the project is rightly scrutinized with the help of descriptive design with selection of descriptive design (Rose, 2009).

Benefit of PERT

There are two kinds of data: Primary Data and Secondary Data. Primary data are collected directly from the respondents, which indicate that the study is more valid and reliable. In case of secondary sources, data are used as widening the concept of research topic that also enables better study of the topic as it involves more data and description (Munier, Jimenez-Saez & Fernandez-Diego, 2013). Here, the data is collected from secondary source.

The data collected via secondary sources. Secondary source includes both the online and offline sources like journals, articles, books, websites, blogs and others.

Excel package is used for the calculation and represent the data properly. Traditional method of PERT is used for network drawing. Slack of the activities is calculated to find out the critical path.  The three times are estimated such optimistic, most likely and pessimistic. The expected time is calculated on the basis of these three times by using the normal formula.

PERT and CPM analysis for taking decision of make or buy in project purchasing

	Activities	Preceding Event	Succeeding Event	Activity Times (Week)	Event Times (Week)	Slack (Week)
		i	j	to	tm	tp	te	TE	TL
a	Obtain detailed specifications and prepare Engineering Drawings	1	2	2	7.5	16	8	8	8	–
b	Preparing purchasing specification and send enquiries for subassembly	2	4	2	4	12	5	13	13	–
c	Same	2	5	2	4	6	4	12	12	–
d	Compute manufacturing costs for subassembly	2	3	1	3.5	9	4	12	14	2
e	Same	2	6	1	2.5	6.5	3	11	14	3
f	Get quotation for subassembly	4	7	4	5.5	10	6	19	21	2
g	Same	5	8	4	8	12	8	20	20	–
h	Review and approval of costs for sub assembly	3	7	1	5	9	5	19	21	2
i	Same	6	8	3	6	9	6	20	20	–
j	Evaluation of quotations for subassembly	7	9	1.5	3	4.5	3	22	24	2
k	Same	8	9	1	4	7	4	24	24	–
l	Make or Buy Decision	9	10	1	2	3	2	26	26	–

Image 5

There are three time estimates for each activity: optimistic (t_o), most likely (t_m) and pessimistic (t_p). The expected time (t_e) is calculated from those time estimates. It is calculated by using following formula:

t_e = [(t_o+ 4t_m + t_p)/6]

After the network is constructed and the critical path is determined, based on the mean time estimate for each activity, variance plays an important role (Saxena, 2011). It may be recollected that the total duration of the project is the sum of the performance times of the activities in the critical path. The expected elapsed time is required to perform each activity in the network based on the normal working condition, number of hours, shifts, etc. After determining of the expected elapsed times, these time estimates are cumulated from start through the completion of various paths. It is convenient to keep T(E) of the start event zero so that it can be scaled to any date. The earliest completion time under normal condition is the commission of the project in 26 days.

In computing the latest allowable time T(L), one works backward from the completion of time for each event, and this is obtained by subtracting the expected elapsed time estimate from the final goal and moving backwards through the various paths. If the project has to be completed in 26 days, T(E) and T(L) will coincide at event 10. Thus the chart is analyzed by adding the estimated times each of many paths from the beginning to the end of the job. In forward pass for converging activities in junctions, the largest value of T(E) is taken; while in backward pass in the reverse direction, for converging values, the smallest value of T(L) is taken. Thus, for every event there are two values T(E) and T(L). T(E) is the result of forward pass, and T(L) is the result of backward pass. Wherever, these two values coincide, the commencement of that activity cannot be postponed without introducing delay in the completion of the project. This value is called slack. This positive difference gives the margin of time by which the commencement of an activity can be deliberately delayed without dislocating the total duration of the project (Baker & Trietsch, 2009). The events with zero slack are identified as critical events, and the path that passes through the critical events is the critical path. The critical path activities together make up one or more continuous paths from the initial to the terminal event. Such a path is termed as critical path. The total slack of any non-critical activity measures the total time by which the activity can be delayed, without affecting the earliest start time of any of the critical activities in the network (Vanhoucke, 2012). The free slack help in measuring the amount of time by an activity can be delayed without affecting the earliest start time of any other activity in the network.

Construction of PERT

The activities that fall on the events of zero slack, trace the critical path. In this project, the critical path is the one along the activities 1, 2, 5, 8, 9 and 10. It implies that each activity in the path is critical, for a delay in any of the events in this path will cause the entire project to fall behind schedule and, thus, defeat the purpose unless additional resources and personnel are available.

Conclusion

In the conclusion it can be said that time management is required to complete the project properly covering all the activities. PERT & CPM technique is very useful technique to analyze and to schedule the all the activities in the project.

Reference List

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