Resource Smoothing
Let's say that you have a resource working 30 hours this week, 10 hours next week, and 20 hours the week after next week. When you apply resource smoothing, the resource will work 20 hours this week, 20 hours next week, and 20 hours the week after. You see, the total amount of hours remains 60 hours, but is more uniformly distributed over the weeks.
Resource smoothing is part of the resource leveling process. In itself, resource smoothing is the process that, not withstanding any constraints imposed during the leveling process, attempts to determine a resource requirement that is "smooth" and where peaks and troughs are eliminated. For example, even if 7 units of a given resource are available at any one time, utilizing 5 of these units each week is preferable to 4 one week, 7 the next, 2 the next and so on. Given that the resource requirements of those activities on the critical path are fixed, some order or priority needs to be established for selecting which activity and which particular resource associated with this activity should be given priority in the smoothing process. In determining which activity should be given priority, activities should be ranked in order of total work content and total float or slack available for that activity. A useful device for prioritizing is to consider the ratio of total work content/total float remaining and give priority to activities with the highest value of this ratio.
Solving the resource scheduling problem for optimal solutions is extremely complex, particularly for large project networks with many different resource types. However, several heuristics are available to solve such problems. These heuristics allocate resources to activities to minimize project delay based on certain priority rules. The two most commonly used heuristics are the serial and the parallel methods. In the serial method of resource allocation, activities are sorted into a list and resources are allocated to each of these activities one at a time until resources are allocated to all activities. In the parallel method, however, resources are allocated on a period by period basis rather than each activity. In this method only those activities whose preceding activities have been completed will be considered. If two or more activities compete for the same resources, then allocation of resources is based on certain prescribed priority rules. Compared to the serial method, the parallel method has been the most widely used heuristic. The following priority rules, in the order presented, have been found to be the most effective in minimizing project delay.
Minimum slack
Smallest duration
Lowest activity identification number
Regardless of the scheduling heuristic used, the primary impact of resource constrained scheduling is the loss of flexibility due to the reduction in slack. Furthermore, the reduction in slack also increases the number of critical or near-critical activities.
Let's say that you have a resource working 30 hours this week, 10 hours next week, and 20 hours the week after next week. When you apply resource smoothing, the resource will work 20 hours this week, 20 hours next week, and 20 hours the week after. You see, the total amount of hours remains 60 hours, but is more uniformly distributed over the weeks.
Resource smoothing is part of the resource leveling process. In itself, resource smoothing is the process that, not withstanding any constraints imposed during the leveling process, attempts to determine a resource requirement that is "smooth" and where peaks and troughs are eliminated. For example, even if 7 units of a given resource are available at any one time, utilizing 5 of these units each week is preferable to 4 one week, 7 the next, 2 the next and so on. Given that the resource requirements of those activities on the critical path are fixed, some order or priority needs to be established for selecting which activity and which particular resource associated with this activity should be given priority in the smoothing process. In determining which activity should be given priority, activities should be ranked in order of total work content and total float or slack available for that activity. A useful device for prioritizing is to consider the ratio of total work content/total float remaining and give priority to activities with the highest value of this ratio.
Solving the resource scheduling problem for optimal solutions is extremely complex, particularly for large project networks with many different resource types. However, several heuristics are available to solve such problems. These heuristics allocate resources to activities to minimize project delay based on certain priority rules. The two most commonly used heuristics are the serial and the parallel methods. In the serial method of resource allocation, activities are sorted into a list and resources are allocated to each of these activities one at a time until resources are allocated to all activities. In the parallel method, however, resources are allocated on a period by period basis rather than each activity. In this method only those activities whose preceding activities have been completed will be considered. If two or more activities compete for the same resources, then allocation of resources is based on certain prescribed priority rules. Compared to the serial method, the parallel method has been the most widely used heuristic. The following priority rules, in the order presented, have been found to be the most effective in minimizing project delay.
Minimum slack
Smallest duration
Lowest activity identification number
Regardless of the scheduling heuristic used, the primary impact of resource constrained scheduling is the loss of flexibility due to the reduction in slack. Furthermore, the reduction in slack also increases the number of critical or near-critical activities.
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