Chapter 8 Flashcards
Types of Project Constraints
Technical or Logic Constraints
Physical Constraints
Resource Constraints
Technical or Logic Constraints
Constraints related to the networked sequence in which project activities must occur.
Physical Constraints
Activities that cannot occur in parallel or are affected by contractual or environmental conditions.
Resource Constraints
The absence, shortage, or unique interrelationship and interaction characteristics of resources that require a particular sequencing of project activities
Kinds of Resource Constraints - people, materials, equipment
Classification of a Scheduling Problem
Classification of Problem
Using a priority matrix will help determine if the project is time or resource constrained.
Time-Constrained Project
Must be completed by an imposed date.
Time is fixed, resources are flexible: additional resources are required to ensure project meets schedule.
Resource-Constrained Project
Is one in which the level of resources available cannot be exceeded.
Resources are fixed, time is flexible: inadequate resources will delay the project.
Resource Solutions
Resource Smoothing (or Leveling) Resource-Constrained Scheduling
Resource-Constrained Scheduling
The duration of a project may be increased by delaying the late start of some of its activities if resources are not adequate to meet peak demands.
Resource Smoothing (or Leveling)
Involves attempting to even out varying demands on resources by using slack (delaying noncritical activities) to manage resource utilization when resources are adequate over the life of the project.
Resource Allocation Methods
Limiting Assumptions
Risk Assumptions
Risk Assumptions
Activities with the most slack pose the least risk.
Reduction of flexibility does not increase risk.
The nature of an activity (easy, complex) doesn’t increase risk.
Limiting Assumptions
Splitting activities is not allowed—once an activity is start, it is carried to completion.
Level of resources used for an activity cannot be changed.
Resource Demand Leveling Techniques for Time-Constrained Projects
Advantages
Peak resource demands are reduced.
Resources over the life of the project are reduced.
Fluctuation in resource demand is minimized.
Disadvantages
Loss of flexibility occurs from reducing slack.
Increases in the criticality of all activities.
Resource-Constrained Projects (Info)
Resources are limited in quantity or availability.
Activities are scheduled using heuristics (rules-of-thumb) that focus on:
Minimum slack
Smallest (least) duration
Lowest activity identification number
The parallel method is used to apply heuristics
An iterative process starting at the first time period of the project and scheduling period-by-period the start of any activities using the three priority rules.
Splitting
A scheduling technique use to get a better project schedule and/or increase resource utilization.
Involves interrupting work on an activity to employ the resource on another activity, then returning the resource to finish the interrupted work.
A major reason why projects fail to meet schedule.
Resources and Priorities
Project network times are not a schedule until resources have been assigned.
The implicit assumption is that resources will be available in the required amounts when needed.
Adding new projects requires making realistic judgments of resource availability and project durations.
Cost estimates are not a budget until they have been time-phased.
Impacts of Resource-Constrained Scheduling
Reduces delay but reduces flexibility.
Increases criticality of events.
Increases scheduling complexity.
May make the traditional critical path no longer meaningful.
Can break sequence of events.
May cause parallel activities to become sequential and critical activities with slack to become noncritical.
Benefits of Scheduling Resources
Leaves time for consideration of reasonable alternatives:
Cost-time tradeoffs
Changes in priorities
Provides information for time-phased work package budgets to assess:
Impact of unforeseen events
Amount of flexibility in available resources
Multiproject Resource Schedules
Multiproject Scheduling Problems
Overall project slippage
Delay on one project create delays for other projects.
Inefficient resource application
The peaks and valleys of resource demands create scheduling problems and delays for projects.
Resource bottlenecks
Shortages of critical resources required for multiple projects cause delays and schedule extensions.
Managing Multiproject Scheduling
Create project offices or departments to oversee the scheduling of resources across projects.
Use a project priority queuing system: first come, first served for resources.
Centralize project management: treat all projects as a part of a “megaproject.”
Outsource projects to reduce the number of projects handled internally.
Using Resource Schedules to Develop a Project Cost Baseline
Why a Time-Phased Budget Baseline Is Needed
To determine if the project is on, ahead, or behind schedule and over or under its budgeted costs?
To know how much work has been accomplished for the allocated money spent—the project cost baseline (planned value, PV)
Creating a Time-Phased Budget
Assign each work package to one responsible person or department and deliverable.
Compare planned schedule and costs using an integrative system called earned value.
Time-constrained project
Completed by an imposed date
If required, resources can be added
Resource-constrained project
Assumes the level of resources availible cannot be exceeded.
The trick is proitize and allocate resources to minimize project delay without exceeding the resource limit or altering the technical network relationships.
Impacts of Resource-constrained project
Reduces slack Reduces flexibility Increases the number critical and near-critical activities Scheduling complexity is increased Critical path is no longer meaningful.
Splitting
A scheduling technique used to get better project schedule and/or to increase resource utilization.
