Scheduling

1
Scheduling
2
Scheduling

• Putting the activities in chronological order
• Chicken or the egg
• Allows the PM to determine the time required to
  complete a project

3
Types of Schedules

• Depend on Viewer
• Simple bar chart (Gantt chart)
• Tells owner progress
• Activity on Node (AON)
• Activity on Arrow (AOA)
• Used by PM, supers, foremen
• Short term schedules
• Monthly , allows for close-up look at schedule

4
Developing Activity Sequence

• Physical Relationship
• An activity cannot start until a previous one is
  complete
• Safety Relationship
• Performing activities which cause a safety hazard
  to other activities
• Resource Relationship
• The amount of resources available at any time
• Preferential Relationship
• Contractors preference on activity order

5
Constructing Bar Chart

• How should bar chart be laid out
• Time on horizontal axis
• Activity on vertical axis
• Time of activity start based on position
• Duration of activity based on length of line
• Day start of day to start of day

6
Constructing Bar Chart

• What time unit should be used
• Work days
• Hours
• Weeks
• What makes sense for your project
• Bar chart size may dictate time units
• Time unit dictates activity size

7
Constructing Bar Chart

• Additional Info
• Activity Value
• Activity Cost
• Activity Resource requirements

8
Constructing Bar Chart

• Work days or Calendar days
• Work days harder to follow
• No weekends or holidays
• Calendar days allow you to see concrete curing

9
Gantt Chart

• Looks like a horizontal bar chart
• Good for linear work
• Good for providing an overview of the project
• Not good for complex projects

10
Gantt Chart
11
Owners Chart
12
Activity Network Development

• Network Models
• Activity on Node
• Precedence Diagram Method
• Activity on Arrow
• Network Characteristics
• Discrete Activities
• Deterministic Durations
• Deterministic Logic
• Activity Flow

13
Network Elements

• Activities
• Basic building block
• Represent tasks
• Must consume time and resources
• Milestones
• Notice to Proceed
• Building Enclosed
• Substantial Completion
• Project Complete
• Activity Relationships
• Physical, Safety, Resource, Preferential

14
Precedence

• Succeeding activities cannot start until
  preceding activities finished
• Changes in duration of one activity affect all
  succeeding activities

15
Activity on Node

• All activities occur at nodes
• Arrows connect nodes and show relationships

16
Activity on Node

• Basics
• Unique Alphanumeric identifier
• Unique description
• Estimated Duration
• Succeeding activity cannot start until preceding
  activity is finished
• Need beginning and ending milestone to tie
  project together

17
Constructing an AON Network

• Sequential logic
• All activities preceding must be finished before
  next activity can start
• Concurrent Logic
• 2 or more activities can be worked at one time

18
Constructing an AON Network

• Multiple Successor Logic
• 2 or more activities can be worked at one time
  after common predecessor is finished
• Multiple Predecessor Logic
• 2 or more activities need to be finished before
  next activity starts

19
Constructing an AON Network

• Combinational Logic
• 2 or more activities can be worked at one time
  after multiple predecessor activities are finished

20
Logic Errors and Problems

• Incorrect Logic
• Activities MUST have a logical connection
• Paint color does not control the roofing
  application
• Redundant Logic
• Not incorrect
• Can cause errors

21
Logic Errors and Problems

• Logic Loops

22
Activity Numbering

• Numbering Activities can make it easier to use
  schedule
• Group like activities under the same general
  numbers
• Activity Category
• WBS can make it easy to categorize resources used
  to each activity
• Work Classification
• Numbers refer to a class of activity

23
Activity Numbering

• Location
• Number activity based on location on project
• Responsibility
• Numbers refer to who is responsible for work

24
Activity Numbering

• Numbering Conventions
• Directional
• Numbers increase from start to finish of project
• Numbering gaps
• Leave gaps between numbers to allow for additions
  to schedule
• Even/Odd Numbering
• Even part of base contract
• Odd additional work

25
Constructing a AON

• Determine the relationships between the
  activities
• Forward Pass
• Determine when each activity can start based on
  the finish of the predecessor activities
• Backward Pass
• Determine when each activity can start based on
  when the successor activities start

26
Constructing a AON
Activity Duration Predecessors
A 6
B 4 A
C 10 B
D 10 C
E 1 D,G,I
F 6 A
G 8 F
H 10 A
I 6 H
27
Constructing a AON

• Critical Path
• Path through schedule which provides the shortest
  time to complete project
• Total Float
• Amount of time that activity can float without
  impacting CP
• Free Float
• Amount of time an activity can be delayed without
  effecting the early start date of the successor
  activity

28
Reviewing the Schedule

• Is Schedule complete
• Are Activity Duration Reasonable
• Are Activity Relationships Complete
• Are Activity Relationships Valid
• Is Project Calendar Correct
• Is Schedule Duration within Contract Time
• Are Contractual Milestones Met

29
Analyzing the Schedule

• Is Critical Path Reasonable
• Are there Multiple Critical paths
• What Activities are Near Critical
• How does Work Flow
• Are there Conflicts Among Concurrent Activities
• Is there an Excessive amount of Work at any Time

30
Value Engineering

• Provides alternatives to the proposed design
• Save Owner
• Must be as good or better than original design
• Must save enough so that contractor can
  recover his cost of doing VE
• Usually comes from contractors or engineers
  previous experience

31
Value Engineering

• Can save either due to savings in time or
  materials
• Ex Composite Wall and roofs
• Material cost per sf is higher than regular roof
• Labor cost is lower
• Requires a crane

32
Value Engineering

• Ex
• Replace infiltrators with Eljen In drains
• System size is reduced to 50
• Also reduces amount of sand, clay, topsoil
• Reduces dozer time and installation time
• In-drain costs about 2x infiltrator

33
Updating Schedule

• Frequency
• Depends on
• Complexity
• More complex -gt more updates
• Unexpected events
• Update after event to determine new completion
  date
• Helps team evaluate strategies to mitigate
  impacts
• When specified
• By contract documents

34
Updating Schedule

• How
• Gather Activity Status Info
• Update Date when the info is gathered
• Activity status
• Actual start date meaningful work begins
• complete
• Work in place -gt work in place/planned work
  quantity
• Time expended -gt time expended/ planned duration
  (only good for time dependent activities like
  concrete curing)
• Cost Incurred - gtcost incurred/planned cost
  (depends on actual resource productivity being
  constant and resource costs not varying)
• Resource used -gt Resource Used/Planned resource
  amount

35
Updating Schedule

• How
• Activity status
• Remaining duration Remaining Work
  quantity/Anticipated Productivity
• Actual finish date all completed activities
• Provides data for future jobs
• Gathering Data
• Direct observation, Update meetings, field
  reports, turnaround reports, photos and videotape

36
Analyzing Schedule Status

• What is the basis for evaluating schedule status?
• Usually the original schedule is the baseline
• What is planned completion date
• Is updated schedule completion date same as
  baseline
• If not why not (is there an error)

37
Analyzing Schedule Status

• Has the critical path shifted?
• If so why
• Are CP activities really critical
• Has the float changed on any activities?
• Has weather become a factor for any activity
• Are there trends worth watching
• Any changes since last update?

38
Modify and Revise Schedule

• Revise network logic
• Change duration to meet contracted completion
• Reflect changes in planned means and methods for
  completing activity
• Shift activity to better time (summer for
  concrete)

39
Modify and Revise Schedule

• Revise Activity Durations
• Planned quantity of work has changed
• Amount of resources has changed
• Productivity is either higher or lower than
  planned
• Add Delete Activities
• Scope of work changed
• Activities divided into smaller activities

40
Review and Analyze Schedule

• Make sure new schedule does not contain errors
• Implement updated schedule

41
Out of Sequence Work

• Why?
• Keep crews busy
• Preparatory work starts early
• Gives crew a chance to test means and methods
• Preserve Schedule Logic
• Shorten successor activity caused by out of
  sequence work
• Keep all other logic intact