During the preliminary planning, following data is collected: –
From this preliminary data, the final planning of the project shall be done in detail. Decision-making becomes easy due to the ‘Detailed planning’
. During the detailed planning, the project shall be divided into number of well manageable activities. These activities have to be performed in a definite sequence for the completion of the project. These different activities consume resources and take time for their completion. To arrive at the logical quantification of the resources and the time, various methods are adopted. In these methods, the various activities are required to be arranged sequentially so as to estimate the correct quantities of various resources, the duration and the exact time of availing the specified quantities of the resources. Bar chart is one of the methods to help to meet the purpose of planning. BAR CHART: – This simple method consists of preparing a graphical presentation, which displays different activities by horizontal bars representing the schedule of different activities. Activities are represented on Y-axis and duration is represented on X-axis. Each bar represents specific activity to be performed along with the commencement and completion of the activity. Beginning and the end of each bar represents the time consumed by that activity.i.e.the duration of the activity. ADVANTAGES OF BAR CHART:
LIMITATIONS OF BAR CHART:
- It is very simple and easy method of
- Each activity is shown separately. Actual progress of work can be compared with proposed schedule. Hence modification can be carried out easily if
- Achievements on a particular date in progress, can be easily
- Cumulative progress can be represented on a bar
- It can represent possible
SPECIMEN BAR CHART: CRITICAL PATH METHOD:
- Interdependence of various activities cannot be shown absolute clearly and sequence of activities is not clear.
- By itself, it does not indicate the progress of the
- It cannot represent and reflect tolerance and uncertainties in time-estimation for various
- It does not give optimum duration of the
- Different alternatives cannot be evaluated from bar
- It is not possible to locate a critical activity, which may delay the project to a great .
As the project and the activities become more and more complex; bar chart method of scheduling becomes less helpful. Therefore to overcome the limitations of scheduling by bar chart; a scientific networking method is developed, known as ‘CRITICAL PATH METHOD’ (C.P.M.) In this method, the objectives of all the activities are defined. These objectives are compound with the targets considering the problems, which may creep-in, before or during the construction. A project is broken into a number of distinct, well-defined tasks or activities. The beginning and end of every activity is called as an EVENT. These events when connected logically and sequentially form a network diagram. Thus this network is a flow diagram. The method to prepare a network diagram is explained in detail. STEPS TO BE PERFOMED IN DEVELOPING NETWORK:
- Breakdown the project, into simple different
- Decide the interrelationship between the activities i.e. decide the preceding & succeeding activity of each activity..
- Decide the sequence of the
- Depending upon the sequence, draw the network.. Dummy activities may be adopted if required for completing the network.
- The network should be carefully studied to see that the sequence & the inter-relationship are well – maintained.
Activity is represented by an arrow Dummy activity is represented by broken arrow Event is represented by circle
RULES FOR FRAMING NETWORK:
- Initial event is the starting of Hence different Activities will emerge from initial node. Hence there is always a single initial node in a network.
- An event cannot be said to have occurred unless all the activities merging in that event are
- No event depends for its occurrence on the occurrence of any succeeding This means that there cannot be any path in the network looping back from a succeeding event to a preceding event. Such a situation known as looping shall not occur anywhere in the network.. If such situation occurs, the logic underlying the diagram must be re-examined & the interrelationship between the activities may be properly decided.
- No activity can start unless the tail event has occurred. There should not be any dead end loop for any activity except the final node, which is the completion of the If it happens, take a dummy activity.
- Any activity in the project should be represented by a single line arrow & each arrow should represent a singular activity & hence the number of arrows must be equal to the number of
- Dummy activities should represent the interdependency
- The activity arrowheads will point towards progress of the project i.e. from left to right. The line flows from left to
- The length of arrow does not indicate the duration of any activity to any scale. Length of an arrow is chosen to suit the drafting
- Curved arrows shall be
- As far as possible, Activity arrows shall not cross each other, but if interdependency demands, the activity arrow should be broken to bridge over the
- Head events have always-higher numbers than the tail-end
IMPORTANT FEATURES OF “CPM”:
- It is applicable to both small & large
- It provides diagrammatic form to the total project, showing independency of various activities. The complete project can be visualized at a
- Critical activities, which affect the project duration, can be easily identified & proper attention can be put, to their
- It is the technique of economic sequence of operation & hence when the minimum overall cost is the main consideration, it is the best planning
- It can ensure better utilization of men, material &
- Slack period (float) available, can be utilized
- Possible bottlenecks & difficulties can be visualized well in
For actual implementation of a project, different resources are required. The resources include men, material, machineries, money & also space. A project cannot commence in the absence of any one of the above five resources. Bar chart or CPM techniques are used for planning & scheduling of a project. A detailed list of all the resources is prepared with the help of a bar chart or CPM technique. The resources are then allocated on monthly basis or on suitable time intervals. In this way, all the resources are spread over in a balanced manner on suitable time duration. This helps to complete the project with a constant pace and harmony.
TIME AND MOTION STUDY:
During the execution of each item of work, every worker, supervisor, manager moves as per the need of the job. The raw material in process, is also moved for various operations on it. The study of this movement of raw material as well as the worker with respect to time is called as “TIME AND MOTION STUDY
”. The objective of this study is to minimize the handling of the material during production and also to minimize the manpower. This study also helps to locate and delete the stressful movements of a worker during production process. The study helps to locate and minimize the idle time of men, machine and improve the outputs. This study helps to pinpoint the probable congestion of traffic of raw material and workers, indirectly reducing the accidents. Time and motion study initially started in the construction industry. Mr. Gilberth first studied the brick masonry item scientifically, to improve the efficiency of mason. But this practice of time and motion study was totally sidetracked afterwards. The use of CPM, PERT and other networking methods were adopted by construction industry with an enthusiasm. This is the most useful method for a supervisor at site level.
But this study is not taught at all, at college education of civil engineering. This method helps to plan and efficiently execute the various items at the actual work place, for a supervisor. It helps to reduce the wastage of material, manpower and time. It helps to keep the work place, safe and clean.
ADVANTAGES OF PLANNING: –
The project planning and process planning helps us in following ways: –
- It decides the earliest and latest starting and finishing dates of all the activities. This in turn, helps to decide the dates for sanctioning, designing and finalizing the
- It decides the exact dates for mobilizing various
- It locates the probable bottleneck in the
- It shows the exact congestion of activities and hence the imbalance in resource allocations. This helps to change the flow of, some of the activities to streamline the cash
- It pinpoints the critical activities, which affect the project
- Process planning locates the exact point of necessary
- It gives us liberty from minor day-to-day problems. It helps to minimize the fatigue due to overtime working.
- It helps to create a good work- culture. This results in healthy work atmosphere, finally leading to good quality
- It helps to carve out leisure time between the processes to overcome the monotony, imposed due to continuous
- It locates the floating time between the various activities. This helps to re plan the project to achieve economy.
- All the above advantages collectively raise confidence level of all the concerned, involved personnel. The initial picture of chaos and a feeling of ‘LOST Control’ is wiped A new picture of ‘total control’ is created.
MONITERING THE PLANNING DURING CONSTRUCTION
The most important reason behind the failure of a very good planning, is the lack of monitoring it. Many times, ‘very good planning’ is done and kept in a file, and then the file is shut and forgotten, till some problem arises. This happens due to lack of habit of monitoring on daily basis ,during the construction . Monitoring helps in many ways, such as;
- The reasons of an activity lagging behind-the-schedule,are This helps to take corrective actions before the project is delayed beyond alarming situations.
- A preventive action is evolved to avoid future congestion and delays.
- The price fluctuations in the market can be judged and suitable advantage can be taken, without hampering the quality and without unbalancing our resources.
- It helps sometimes, to complete the total project, even before-time
- In this manner, it helps to avoid complications due to delay, such as, penalties, strained customer relations and
Therefore monitoring the planning on daily basis shall be treated as a critical activity in a project