Scheduling
• Putting the activities in chronological order– Chicken or the egg
• Allows the PM to determine the time required to complete a project
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
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
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
Constructing Bar Chart
• What time unit should be used– Work days– Hours– Weeks– Bar chart size may dictate time units
Constructing Bar Chart
• Additional Info– Activity Value– Activity Cost– Activity Resource requirements
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
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
Gantt Chart
ID Task Name Duration
1 Excavate foundation 2d
2 Form footings 1d
3 Pour footings 2d
4 strip footings 1d
5 Form foundation walls 1d
6 Pour foundation walls 3d
7 Strip forms 1d
8 Frame 1st floor 2d
9 Backfill foundation 1d
10 Frame 1st floor walls 2d
11 Frame 2nd floor 2d
12 Frame 2 floor walls 2d
13 Frame 2nd floor ceiling 1d
14 Frame roof 3d
15 Shingle roofing 4d
16 Rough plumbing 3d
17 Rough electric 3d
18 Insulation 2d
19 Drywall 3d
20
21
22
23
24
F S S M T W T F S S M T W T F S S M T W T F S S M T W T F S S M T W T F S S M T WApr 7, '02 Apr 14, '02 Apr 21, '02 Apr 28, '02 May 5, '02 May 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
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
Precedence
• Succeeding activities cannot start until preceding activities finished
• Changes in duration of one activity affect all succeeding activities
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
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
100Excavate Footings
2
110Form & Reinforce Ftg
2
100Excavate Footings
2
110Form & Reinforce Ftg
2
120Install f loor drains
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
100Excavate Footings
2
110Form & Reinforce Ftg
2
120Install f loor drains
100Excavate Footings
2
110Form & Reinforce Ftg
2
120Install f loor drains
Constructing an AON Network
• Combinational Logic– 2 or more activities can
be worked at one time after multiple predecessor activities are finished
100Excavate Footings
2
110Form & Reinforce Ftg
2
120Install f loor drains
115Trench for floor drains
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
100Excavate Footings
2
110Form & Reinforce Ftg
2
120Pour Footing
2
Logic Errors and Problems
– Logic Loops
100Excavate Footings
2
110Form & Reinforce Ftg
2
120Pour Footing
2
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
Activity Numbering
– Location• Number activity based on location on project
– Responsibility• Numbers refer to who is responsible for work