Resource Leveling in Construction Projects - Revision history

Onur at 11:58, 8 May 2023

2023-05-08T11:58:36Z

← Older revision		Revision as of 11:58, 8 May 2023
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	</ul></div>		</ul></div>

	<br clear=all>When the tasks are scheduled according to the CPM above, daily consumption of Resource 1 and Resource 2 are given below. ~~Stiff~~ rises, peaks and valleys can be observed on the graphs.		<br clear=all>When the tasks are scheduled according to the CPM above, daily consumption of Resource 1 and Resource 2 are given below. Drastic rises, peaks and valleys can be observed on the graphs.

	<div><ul>		<div><ul>

Onur at 11:46, 8 May 2023

2023-05-08T11:46:30Z

← Older revision		Revision as of 11:46, 8 May 2023
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	Resource leveling isn’t a technique that can be implemented to construction projects solely. Resource leveling is often coupled with a scheduling method, because resource leveling requires knowledge on the schedule of the project for rearranging start dates of non-critical activities (activities that doesn’t cause any delay when the schedule is changed). Construction projects use several scheduling techniques, namely Gantt Charts, Critical Path Method (CPM) and Program Evaluation and Review technique (PERT) [2]. However, each of these scheduling techniques have some shortcomings. The Gantt Chart simply demonstrates the durations of the activities but it doesn’t display a network. The Gantt Chart cannot determine connections between individual activities; hence Gantt Chart cannot be used for defining debut and completion times of the activities [1]. Even though they have drawbacks, CPM and PERT, which are network-based scheduling techniques, have been commonly used in construction projects [1]. Critical Path Method has been the most popular scheduling technique since the 1950s [1]. A complete network of activities demonstrates the links between the activities and their durations [1]. The Critical Path Method has the disadvantage of assuming that all the resources are unlimited [2]. Although network based scheduling techniques are the pillars in scheduling in construction projects, they ~~doesn’t~~ pay attention to the resource availability and they focus on minimizing the construction duration [1]. This prioritization can easily cause peaks and valleys in resource utilization.		Resource leveling isn’t a technique that can be implemented to construction projects solely. Resource leveling is often coupled with a scheduling method, because resource leveling requires knowledge on the schedule of the project for rearranging start dates of non-critical activities (activities that doesn’t cause any delay when the schedule is changed). Construction projects use several scheduling techniques, namely Gantt Charts, Critical Path Method (CPM) and Program Evaluation and Review technique (PERT) [2]. However, each of these scheduling techniques have some shortcomings. The Gantt Chart simply demonstrates the durations of the activities but it doesn’t display a network. The Gantt Chart cannot determine connections between individual activities; hence Gantt Chart cannot be used for defining debut and completion times of the activities [1]. Even though they have drawbacks, CPM and PERT, which are network-based scheduling techniques, have been commonly used in construction projects [1]. Critical Path Method has been the most popular scheduling technique since the 1950s [1]. A complete network of activities demonstrates the links between the activities and their durations [1]. The Critical Path Method has the disadvantage of assuming that all the resources are unlimited [2]. Although network based scheduling techniques are the pillars in scheduling in construction projects, they don’t pay attention to the resource availability and they focus on minimizing the construction duration [1]. This prioritization can easily cause peaks and valleys in resource utilization.



	= Schedule Flexibility & Float =		= Schedule Flexibility and Float =

Onur at 17:08, 6 May 2023

2023-05-06T17:08:51Z

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	<div><ul>		<div><ul>
	<li style="display: inline-block;"> [[File:RLfCP_E4.png\|~~450px~~\|thumb\|left\|Resource 1 consumption before resource leveling]] </li>		<li style="display: inline-block;"> [[File:RLfCP_E4.png\|400px\|thumb\|left\|Resource 1 consumption before resource leveling]] </li>

	<li style="display: inline-block;"> [[File:RLfCP_E5.png\|~~450px~~\|thumb\|left\|Resource 2 consumption before resource leveling]] </li>		<li style="display: inline-block;"> [[File:RLfCP_E5.png\|400px\|thumb\|left\|Resource 2 consumption before resource leveling]] </li>
	</ul></div>		</ul></div>

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	<div><ul>		<div><ul>
	<li style="display: inline-block;"> [[File:RLfCP_E8.png\|~~450px~~\|thumb\|left\|Resource 1 consumption before and after resource leveling]] </li>		<li style="display: inline-block;"> [[File:RLfCP_E8.png\|500px\|thumb\|left\|Resource 1 consumption before and after resource leveling]] </li>

	<li style="display: inline-block;">[[File:RLfCP_E9.png\|~~450px~~\|thumb\|left\|Resource 2 consumption before and after resource leveling]] </li>		<li style="display: inline-block;">[[File:RLfCP_E9.png\|500px\|thumb\|left\|Resource 2 consumption before and after resource leveling]] </li>
	</ul></div>		</ul></div>

Onur at 17:04, 6 May 2023

2023-05-06T17:04:55Z

← Older revision		Revision as of 17:04, 6 May 2023
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	Resource leveling alters the schedule of the construction project. It is possible to rearrange the dates of some independent tasks or some necessary tasks which demands less time than other crucial tasks without changing the total duration of the work chain. The total availability of float gives schedule flexibility [5]. The scheduler should find a balance between resource use and schedule flexibility while producing a solution for resource leveling problem [1]. The time availability, which allows move of the start and completion dates of certain tasks without changing total duration, is called float. If a task is suitable for resource leveling, the start time of the task moves forward or backward by using total float [3]. Float is a valuable commodity for both clients and contractors in construction sector [1]. On the other hand, inconsiderate consumption of the float is dangerous. Because, in that case, activities become critical. Any unexpected delays or problems in activities which doesn’t have float would cause delays and potentially cost overruns [5]. An amount of float can be left while rescheduling non critical activities as a precaution. Schedule flexibility is essential for resource leveling and it can also be a safety factor.		Resource leveling alters the schedule of the construction project. It is possible to rearrange the dates of some independent tasks or some necessary tasks which demands less time than other crucial tasks without changing the total duration of the work chain. The total availability of float gives schedule flexibility [5]. The scheduler should find a balance between resource use and schedule flexibility while producing a solution for resource leveling problem [1]. The time availability, which allows move of the start and completion dates of certain tasks without changing total duration, is called float. If a task is suitable for resource leveling, the start time of the task moves forward or backward by using total float [3]. Float is a valuable commodity for both clients and contractors in construction sector [1]. On the other hand, inconsiderate consumption of the float is dangerous. Because, in that case, activities become critical. Any unexpected delays or problems in activities which doesn’t have float would cause delays and potentially cost overruns [5]. An amount of float can be left while rescheduling non critical activities as a precaution. Schedule flexibility is essential for resource leveling and it can also be a safety factor.

			<div><ul>
			<li style="display: inline-block;"> [[File:RLfCP_F1.png\|500px\|thumb\|left\|Float]] </li>
			</ul></div>


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	[[File: RLfCP_E1.png\|250px\|thumb\|left\|Tasks, durations and consumptions]]		[[File: RLfCP_E1.png\|250px\|thumb\|left\|Tasks, durations and consumptions]]
	<br clear=all>For example: Task 1 consumes 6 units of “Resource 1” every day for 4 days.		<br clear=all>For example: Task 1 consumes 6 units of “Resource 1” every day for 4 days.


	Critical Pathway Method is commonly used in construction projects, because it shows dependencies between tasks. CPM of 14 tasks is given below. The schedule follows early start and early finish dates without using available float. Green boxes are start and finish dates of the tasks on the critical path. In other words, tasks without float or tasks which can’t be rescheduled for resource scheduling. Their rescheduling would alter the project duration. Yellow boxes are task numbers. A Gantt Chart is below for better visualization.		Critical Pathway Method is commonly used in construction projects, because it shows dependencies between tasks. CPM of 14 tasks is given below. The schedule follows early start and early finish dates without using available float. Green boxes are start and finish dates of the tasks on the critical path. In other words, tasks without float or tasks which can’t be rescheduled for resource scheduling. Their rescheduling would alter the project duration. Yellow boxes are task numbers. A Gantt Chart is below for better visualization.

Onur at 13:51, 6 May 2023

2023-05-06T13:51:08Z

← Older revision		Revision as of 13:51, 6 May 2023
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	Arr = average resource usage		Arr = average resource usage



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	==3. Metaheuristic Method==		==3. Metaheuristic Method==

	Metaheuristic method takes inspiration from the nature and tries to replicate natural phenomenons in calculations. The reasoning behind this method is the thought that everything in the nature is in its most efficient form for survival. The approach is generating a solution in a short time by mimicking effectiveness of the nature. Metaheuristics can serve for providing solutions to complex optimization problems [2]. Metaheuristic method mainly focuses on iterative process for near optimal results. Metaheuristics link heuristic approach with different learning strategies for structuring information and iteratively searching in a larger space in order to efficiently produce near optimal solutions [2]. Two commonly used metaheuristic approaches by researchers are genetic algorithm, which takes inspiration from biological evolution, and particle swarm ~~organization~~ [4]. The metaheuristic method is fast but it may fail to generate the best results in all conditions.		Metaheuristic method takes inspiration from the nature and tries to replicate natural phenomenons in calculations. The reasoning behind this method is the thought that everything in the nature is in its most efficient form for survival. The approach is generating a solution in a short time by mimicking effectiveness of the nature. Metaheuristics can serve for providing solutions to complex optimization problems [2]. Metaheuristic method mainly focuses on iterative process for near optimal results. Metaheuristics link heuristic approach with different learning strategies for structuring information and iteratively searching in a larger space in order to efficiently produce near optimal solutions [2]. Two commonly used metaheuristic approaches by researchers are genetic algorithm, which takes inspiration from biological evolution, and particle swarm optimization [4]. The metaheuristic method is fast but it may fail to generate the best results in all conditions.

Onur at 13:48, 6 May 2023

2023-05-06T13:48:48Z

← Older revision		Revision as of 13:48, 6 May 2023
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	Arr = average resource usage		Arr = average resource usage




	= Optimization Methods =		= Optimization Methods =

Onur: /* Objective Functions */

2023-05-06T13:48:21Z

Objective Functions

← Older revision		Revision as of 13:48, 6 May 2023
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	'''1. Minimization of the sum of the absolute deviations in daily resource usage''' [2]		'''1. Minimization of the sum of the absolute deviations in daily resource usage''' [2]


	<math>Z=min\sum_{i=1}^{T}\left\|{\rm Rdev}_i\right\|</math>		<math>Z=min\sum_{i=1}^{T}\left\|{\rm Rdev}_i\right\|</math>
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	'''2. Minimization of the sum of only the increases in daily resource usage from one day to the next''' [2]		'''2. Minimization of the sum of only the increases in daily resource usage from one day to the next''' [2]


	<math>Z=min\sum_{i=1}^{T}\left\|{\rm Rinc}_i\right\|</math>		<math>Z=min\sum_{i=1}^{T}\left\|{\rm Rinc}_i\right\|</math>
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	'''3. Minimization of the sum of the absolute deviations between daily resource usage and the average resource usage''' [2]		'''3. Minimization of the sum of the absolute deviations between daily resource usage and the average resource usage''' [2]


	<math>Z=min\sum_{i=1}^{T}\left\|R_i-A_{rr}\right\|</math>		<math>Z=min\sum_{i=1}^{T}\left\|R_i-A_{rr}\right\|</math>
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	'''4.Minimization of the maximum daily resource usage''' [2]		'''4.Minimization of the maximum daily resource usage''' [2]


	<math>Z=min\left[max\left(R_i\right)\right] </math>		<math>Z=min\left[max\left(R_i\right)\right] </math>
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	'''5. Minimization of the maximum deviation in daily resource usage''' [2]		'''5. Minimization of the maximum deviation in daily resource usage''' [2]


	<math>Z=min\left[max\left\|{\rm Rdev}_i\right\|\right]</math>		<math>Z=min\left[max\left\|{\rm Rdev}_i\right\|\right]</math>
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	'''6. Minimization of the maximum absolute deviation between daily resource usage and the average resource usage''' [2]		'''6. Minimization of the maximum absolute deviation between daily resource usage and the average resource usage''' [2]


	<math>Z=min\left[max\left\|R_i-A_{rr}\right\|\right]</math>		<math>Z=min\left[max\left\|R_i-A_{rr}\right\|\right]</math>
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	'''7. Minimization of the sum of the square of daily resource usage''' [2]		'''7. Minimization of the sum of the square of daily resource usage''' [2]


	<math>Z=minM_x=\sum_{i=1}^{T}\left(R_i\right)^2</math>		<math>Z=minM_x=\sum_{i=1}^{T}\left(R_i\right)^2</math>
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	'''8. Minimization of the sum of the square of the deviations in daily resource usage''' [2]		'''8. Minimization of the sum of the square of the deviations in daily resource usage''' [2]


	<math>Z=min\sum_{i=1}^{T}\left({\rm Rdev}_i\right)^2</math>		<math>Z=min\sum_{i=1}^{T}\left({\rm Rdev}_i\right)^2</math>
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	'''9. Minimization of the sum of the square of the deviations between daily resource usage and the average resource usage''' [2]		'''9. Minimization of the sum of the square of the deviations between daily resource usage and the average resource usage''' [2]


	<math>Z=min\sum_{i=1}^{T}\left(R_i-A_{rr}\right)^2</math>		<math>Z=min\sum_{i=1}^{T}\left(R_i-A_{rr}\right)^2</math>
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	Arr = average resource usage		Arr = average resource usage



	= Optimization Methods =		= Optimization Methods =

Onur at 13:41, 6 May 2023

2023-05-06T13:41:29Z

Show changes

Onur at 12:53, 6 May 2023

2023-05-06T12:53:19Z

← Older revision		Revision as of 12:53, 6 May 2023
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	Arr = average resource usage		Arr = average resource usage



	= Optimization Methods =		= Optimization Methods =

Onur: /* Objective Functions */

2023-05-06T12:52:31Z

Objective Functions

← Older revision		Revision as of 12:52, 6 May 2023
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	Rdevi = deviation between resources required on day i and i+1		Rdevi = deviation between resources required on day i and i+1


	----		----


	'''2. Minimization of the sum of only the increases in daily resource usage from one day to the next''' [2]		'''2. Minimization of the sum of only the increases in daily resource usage from one day to the next''' [2]
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	Rinci = increase in between resources required on day i and i+1		Rinci = increase in between resources required on day i and i+1


	----		----


	'''3. Minimization of the sum of the absolute deviations between daily resource usage and the average resource usage''' [2]		'''3. Minimization of the sum of the absolute deviations between daily resource usage and the average resource usage''' [2]
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	Arr = average resource usage		Arr = average resource usage


	----		----


	'''4.Minimization of the maximum daily resource usage''' [2]		'''4.Minimization of the maximum daily resource usage''' [2]
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	Ri = resources required on day i and i+1		Ri = resources required on day i and i+1


	----		----


	'''5. Minimization of the maximum deviation in daily resource usage''' [2]		'''5. Minimization of the maximum deviation in daily resource usage''' [2]
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	Rdevi = deviation between resources required on day i and i+1		Rdevi = deviation between resources required on day i and i+1


	----		----


	'''6. Minimization of the maximum absolute deviation between daily resource usage and the average resource usage''' [2]		'''6. Minimization of the maximum absolute deviation between daily resource usage and the average resource usage''' [2]
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	Arr = average resource usage		Arr = average resource usage


	----		----


	'''7. Minimization of the sum of the square of daily resource usage''' [2]		'''7. Minimization of the sum of the square of daily resource usage''' [2]
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	Ri = resources required on day i and i+1		Ri = resources required on day i and i+1


	----		----


	'''8. Minimization of the sum of the square of the deviations in daily resource usage''' [2]		'''8. Minimization of the sum of the square of the deviations in daily resource usage''' [2]
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	Rdevi = deviation between resources required on day i and i+1		Rdevi = deviation between resources required on day i and i+1


	----		----


	'''9. Minimization of the sum of the square of the deviations between daily resource usage and the average resource usage''' [2]		'''9. Minimization of the sum of the square of the deviations between daily resource usage and the average resource usage''' [2]
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	Arr = average resource usage		Arr = average resource usage



	= Optimization Methods =		= Optimization Methods =