Network Planning Method

Network Planning Method Various types of network analysis, which are very widely used are the critical path method (CPM-Critical Path Methode), and the project evaluation and review technique (PERT-Project Evaluation and Review Technique). a. PERT Method The network method for project scheduling known as PERT, was first developed in 1957 by the Navy's special project office in collaboration with Booz, Allen, and Hamilton. Roger G Schroeder (2000:293) defines that "PERT is a network-based project scheduling method that requires three time estimates for each activity: optimistic, most likely, and pessimistic. Using these three time estimates, a probability of project completion by any specified date can be computed, along with the standard start and finish times for each activity or event". Meaning: PERT is a network-based project scheduling method that requires three time estimates for each activity: optimistic, most likely, and pessimistic, using three standard start and end time estimates for each activity or event. PERT uses a statistical approach with three estimated time numbers, namely. a. Estimated optimal time (o), which is the shortest time to complete an activity if everything goes smoothly. b. Estimated most likely time (m), which is the time that occurs most often compared to others, if repeated with almost the same conditions. c. Estimated pessimistic time (p), which is the longest time to complete an activity if everything has obstacles. To calculate the expected duration time, namely by using the formula. b. CPM (Critical Path Method) The critical path method (CPM) was first used in the Du Pont company construction project in 1957. This method emphasizes more on project costs. This method is different from PERT which emphasizes more on time uncertainty, and for research and development (R&D) projects. In CPM there is no application of statistical methods to accommodate uncertainty. In CPM also discussed the existence of bargaining or trade off between the schedule time and project costs. Roger G Schroeder (2000:293), defines that: Critical Path Method (CPM) is a network-based method that uses a linear time-cost tradeoff. Each activity can be completed in less than its normal time by crashing the activity for a given cost. Thus, if the normal project completion time is not satisfactory, certain activities can be crashed to complete the project in less time at greater cost. This means: Critical Path Method (CPM) is a basic network method that uses a linear balance of time and cost. Each activity can be completed in less than normal time by bypassing activities to provide costs. Thus, if the completion of the normal time is not satisfactory, certain activities can be bypassed to complete the project in less time at the best cost. In the critical path identification process, several terminologies and calculation formulas are introduced as follows. a. TE = E The earliest time an event occurs b. TL = L The latest time an event may occur. c. ES (Earliest Start Time) The earliest time an activity occurs. d. EF (Earliest Finish Time) The earliest finish time an activity occurs. e. LS (Latest Allowable Start Time) The latest time an activity may start. f. LF (Latest Allowable Finish Time) The latest time an activity may finish. g. D (Duration) The time period of an activity. Generally with units of days, weeks, months, etc. h. S (Foat) The time period that is a measure of the tolerance limit for activity delays. General requirements of a critical path: i. In the first activity ES = LS = 0 j. In the last activity EF = LF k. Total Float = 0 c. Precedence Diagram Method PDM (Precedence Diagram Method) was introduced by J. W. Fondahl from Stanford University USA in the early 60s. The PDM method is a work network that includes the classification of activities in nodes or also called Activity On Node (AON). Activities are written in nodes that are generally rectangular, while the arrows are only as an indication of the relationship between the activities concerned and do not state the time period of the activity. The advantages of the PDM method compared to the arrow diagram are: 1) Does not require fictitious/dummy activities so that network creation becomes simpler. 2) Different overlapping relationships can be created without increasing the number of activities In its use, PDM is easier to complete with the help of computer programs, such as: Harvard total project manager, Project scheduler network, Primavera project planner, Microsoft project and others. d. Several Provisions in Network Planning Wulfram I. Ervianto (2000:162), states the provisions in network planning as follows: 1) In its depiction, the network diagram must be clear and easy to read. 2) Must start and end at event I occurrence. 3) Activities are symbolized by arrows that can be depicted 4) with straight lines or broken lines. 5) As much as possible, intersections between arrows must be avoided. 6) Between two events there can only be one arrow. 7) The use of pseudo activities uses dotted lines and the necessary amount.