07 resource allocation leveling

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Resource Management:Resource Allocation

and Leveling

COSC 621Advanced Construction Project

Scheduling & Management

Introduction

A

B

C

D

E

2 2 2

1 1 1

2 2 2 2

2 2 2 2 2

2 2 2

2 2 5 3 3 2 2 2 2 4 4 2 2 2

22

2

IntroductionAssumption

We have all the resources needed for the scheduleReality

Resources may not be available when needed.Solution

Special adjustments have to be made to the schedule to properly manage available resources and meet project constraints.

How toResource LevelingResource AllocationTime-Cost Tradeoff

Resource Management AnalysisSmoothing Resource Profiles (Resource Leveling)

Apply when it is desired to reduce the hiring and firing of resources and to smooth the fluctuation in the daily demand of aresource.Resources are not limited and project duration is not to be delayed.The objective is to shift non-critical activities within their float times so that a better resource profile is obtained.

Time

Resource

Time

Resource

3

Resource Management Analysis

Scheduling with Limited Resources (Resource Allocation)

Apply when the original schedule shows that several activities require a certain resource at the same time.If the resource is limited, one of the activities has to be delayed, thus delaying the whole project.The objective is to properly select which activities to delay and which one to start so that the total project delay is minimized.

Resource Management Analysis

Meeting a Deadline Duration (Time-Cost Tradeoff)Apply when the project duration determined by the CPM and PDM analyses is unacceptably large and extends beyond a desired deadline.The objective is to apply overtime strategy to crash the project duration so that the total project cost is minimized and the deadline is meet.

4

Smoothing Resource Profiles(Resource Leveling)

ObjectiveHire the minimum number of resourcesReduce daily resource fluctuationEnsure better utilization of our resources.

E.g. The full utilization of a rented piece of equipment that needs to be returned early, also reducing the number of skilled workers.

MethodologyShift non-critical activities within their float times so as to move resources from the peaks to the valleys, without any project delay.

Bottom LineCritical activities remain unchangedNo project delays

Smoothing Resource Profiles(Resource Leveling)

Desired Profile for Labor Resource

Desired Profilefor Equipment & Material

- Slow progress in beginning (small number hired)- Steady progress midway (full number hired)- Slow progress at end (slow resource release)

- Good for arranging storage needs- Good utilization of the resource

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Resource Leveling:Manual Heuristic Solution

Manual Heuristic Solution: Method of Moments

Minimum Moment AlgorithmMinimize daily fluctuations in resource useUse the moment of the resource histogram around the horizontal axis (time).

Resource Leveling:Manual Heuristic Solution

1 2 3 4 5 6 7 8 9 10 11 12

1

2

3

4

5

6

7

H1Mx=160My=16640 RD

H2Mx=166My=25540 RD

Days

Res

ourc

e am

ount

( )∑=

××=

n

jjjxM

1

Demand Resource21Demand Resource1

Minimum Moment Algorithm

(Equation 1)

6

Resource Leveling:Modified Heuristics

Double Moments AlgorithmMinimum Moment method does not consider the resource utilization period.Very important, particularly for equipment resources that are shared among projects or rented from external sources.


1 2 3 4 5 6 7 8 9 10 11 12

1

2

3

4

5

6

7

H3Mx=160My=31640 RD

Days

Res

ourc

e am

ount

Double Moments Algorithm

13

(Mx)1 = (Mx)3 < (Mx)2The single moment Mx does not consider for the extended assignment of the resource.

7



The value My gets higher as the resource remains employed in the project till a later date.My can be used as a good indicator of the resource release date in the project.

( )[ ]( )( )( ) 316

255

220

Demand Resource1

3

2

1

1

=

=

=

××= ∑=

y

y

y

n

jjy

M

M

M

jM (Equation 2)



( ) ( )[ ]∑=

−××=n

jjy kjM

1Demand Resource1

Resource Utilization Period

ResourceStart Dayk=3

ProjectStart Day

Res

ourc

e am

ount

Days

(Equation 3)

8


Minimize the Mx alone when the focus is on reducing daily resource fluctuationsMinimize the My alone when the focus is on reducing the resource utilization periodMinimize the My alone when the focus is on releasing the resource at an early dateMinimize the double moments (Mx + My) when the focus in on both aspects


Shortage of resources is a major challenge for construction projects.

The number of skilled labor is limitedExpensive equipment is shared among several projectsMaterial quantity is limitedLimited space is available for storage

Scheduling under these resource constraints becomes a complex problem, particularly when more than one resource is limited.

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A

B

C

D

E

2 2 2

1 1 1

2 2 2 2

2 2 2 2 2

2 2 2

2 2 5 3 3 2 2 2 2 4 4 2 2 2

22

Maximum available labors = 3


Possible SolutionPrioritize the parallel activitiesGive the resource to higher priority activitiesDelay the others until the earliest time the resource becomes available again

If one activity is delayed, another resource conflict arises later.

Is there an optimum way to prioritize the activities that compete for the limited resource at any time so that the net project delay is minimized?

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Mathematical optimization, Dynamic programming, Linear programming

Applicable only to very small-size problems.Heuristic solutions

Use simple rules of thumbEg: the resource can be assigned to activity that have smaller total float values than others.

Usable for large-scale problems


All heuristic rules are based mainly on an activity characteristic

DurationTotal floatNumber of successors

Two most effective and commonly used heuristic rules

Least Total-Float (LTF)Earliest Late-Start (ELS)

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The project is scheduled to be 32 days when any resource limits are not considered.

Activity (Duration)

R1, R2, R3


1626J22210K

2626I1828H60.25216G8210F

221.024E141.028D1422C

0.526B1024A

L3=2L2=1L1=6Late Start

Required ResourcesDurationActivity

12


40Start626002I22

………………………

2216-

ContinueContinue

Delay

--8

--

14

000

0.2501

222

GFD

8

82216-

ContinueStartStartDelay

-16108

-6814

0000

00.25

01

2222

JGFD

6

68-

ContinueContinue

Delay

--8

--

14

000

0.501

222

BJD

4

648

ContinueContinue

Start

--6

--

16

000

0.500

222

BAJ

2

642

StartStartStart

642

01014

000

0.500

222

BAC

0

L3=2L2=1L1=6Finish TimeDecisionDuration

Priority Rule(Late Start)

Required ResourcesEligibleActivities

Time

Example

257261Q2T

432642P,R6S

13181610107Daily Resource Limits

873335D,O2R

432454O8Q

874323J,M,N5P

326455L3O

143441F,L2N

842222I,K4M

438223E,G,H2L

154233C,E1K

376451F6J

243423G,H2I

190455A,B2H

893414D2G

529414C5F

083253A,B7E

4553456D

132442A4C

6932533B

4722256A

R6R5R4R3R2R1

Resource Requirements per DayPredecessorActivities

Duration(days)

ActivityName

13

Example

Manual Calculation of Resource Allocation49 days

Example: Microsoft Project

14

Example: Microsoft Project

Example : Microsoft Project

15



16



17



18


Resource Allocation:Multi-skilled Resources

Assumption of most resource allocation techniques

Single-skilled resourcesWhat if 2 R4 can substitute 1 R1?

Need education

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6812

648

642

Finish Time

2 L3=1 L2

ContinueContinue

Start

--8

--

14

00

0+1

0.50

1-0.5

222

BJD

4

ContinueContinue

Start

--6

--

16

000

0.500

222

BAJ

2

StartStartStart

642

01014

000

0.500

222

BAC

0

L3=2L2=1L1=6

Substitution Rule Used

DecisionDurationPriority Rule

(Late Start)


Time

68-

ContinueContinue

Delay

--8

--

14

000

0.501

222

BJD

4

648

ContinueContinue

Start

--6

--

16

000

0.500

222

BAJ

2

642

StartStartStart

642

01014

000

0.500

222

BAC

0

L3=2L2=1L1=6

Finish TimeDecisionDuration

Priority Rule

(Late Start)


Time


Example: what if2 R5 = 1 R12 R4 = 1 R22 R5 = 1 R42 R4 = 1 R52 R6 = 1 R5

07 resource allocation leveling

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