Resource Allocation

1
Resource Allocation

• Dr. Dale Masel
• ISE 536
• February 14, 2004

2
Resource Allocation

• Projects Compete for Resources
• Resources that are consumed
• Resources that are not consumed
• Goal Optimize use of Limited Resources
• Requires trade-offs

3
Expediting a Task

• Complete task more quickly
• Reduce length of critical path
• Make up for delays on critical path
• Release resource more quickly
• Additional Cost Crash Cost
• Compare activities based on crash cost per day

4
Crashing Example
Must be 4 or 6 days only
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Example Before Crashing
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Choosing Activity to Crash

• Look at critical path
• Choose activity that has lowest crash cost per
  day
• May need to consider other dependencies
• Need to re-verify critical path after each
  crashing

7
Crashing Example
Path A-B 15 days Path A-C 15 days
Crash Costs A 30/day B 20/day C
25/day
8
Excel Solver

• Target Cell
• Value you want to minimize or maximize
• Changing Cells
• Parameters that can vary
• Constraints
• Conditions that cant be violated

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Excel Solver for Crashing

• Target Cell
• Crashing costs ? Minimize
• Changing Cells
• Amount of crashing to do
• Time each event occurs
• Constraints
• Amount each activity can be crashed
• Precedence relationships
• Completion Deadline
• Nonnegativity

10
Fast-Tracking

• Another type of expediting
• Primarily in construction industry
• Building phase starts before design and planning
  phases are done
• Typically used when large portion of work is
  routine

11
Resource Loading

• Schedule of resource usage
• Amount of resources required
• Associated activity
• Required times
• Usually a list or table

12
Ex Action Plan with Resources
13
Workforce Capacity Analysis

• Concerns
• Having enough hours available to complete project
• Not having unused capacity
• Uncertainty in
• Hours required
• Hours available

14
Determining Workforce Capacity

• Calculate hours available
• workers x hours/day x days
• Consider holidays, vacations
• Compare with workload required
• Dealing with overloads
• Shift activities to slow times
• Overtime

15
Capacity Available vs. Required
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Allocating Resources

• Begin with PERT/CPM Schedule
• Activities examined
• Period-by-period
• Resource-by-resource
• If Demand exceeds Supply
• Consider tasks individually
• Assign resources based on priority

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Constrained Resources

• Scarcity of resources rarely applies to resources
  in general
• Examples of Priority Rules
• As soon as possible
• As late as possible
• Shortest task duration first
• Minimum slack first
• Most critical followers
• Most successor
• Most resources first

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Choosing a Priority Rule

• Schedule Slippage
• Amount project would be delayed
• Resource Utilization
• Extent that resources are overworked or
  underworked
• In-Process Inventory
• Amount of unfinished work

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Resources for Multiple Projects

• Projects compete for resources
• Not efficient to have separate resources for each
  project
• Knowledge/skill required may not be available
  elsewhere
• Use Pseudoactivities
• Link several projects together
• Characteristics
• Do have duration
• Do not require any resources
• Allows set of projects to be treated like a
  single project

20
Life Cycle Resource Allocation

• S-Shaped Life Cycle
• Less impact when resources are withdrawn at end
• J-Shaped Life Cycle
• Significant impact when resources are withdrawn
  at end

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Goldratts Critical Chain

• Theory of Constraints
• The Goal (1992)
• Improvements in a process should focus on the
  bottleneck activities
• Critical Chain (1997)

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Critical Chain (1997)

• Applies Goldratts Theory of Constraints to
  project management
• Many people have same problems on projects
• Unrealistic due dates
• Too many changes
• Resources and data not available
• Unrealistic budget
• These issues caused by need to make trade-offs
• Goldratts Question
• To what extent are these problems caused by human
  decisions and practices?

23
Three Project Scenarios
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Multitasking

• Example Two Small Projects

Alternate Gantt Charts
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Common Chain of Events

• Underestimate time needed to complete project
• Assuming known activity times
• Assuming independent paths
• Project team members inflate time estimates
• Work fills available time
• Student syndrome ? Work up to due date
• Early completions not reported

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Common Chain of Events (contd)

• Safety time misused
• Results in missed deadlines
• Complicates prioritizing of activities
• Lack of clear priorities results in poor
  multitasking
• Increases task durations
• Uneven demand on resources
• More projects undertaken to ensure all resources
  fully utilized
• Leads to poor multitasking

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Reversing the Cycle

• Reduce number of projects assigned to each
  individual
• Schedule start of new projects based on
  availability of bottleneck resources
• Reduce amount of safety time added to individual
  tasks

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The Critical Chain

• Longest chain of consecutively dependent events
• Consider precedence relationships
• Consider resource dependencies
• Use Buffers
• Project buffer
• Feeding buffer