L2 - CPM Building Blocks

Question 1

Essential ingredients

Answer 1

Activities
Durations
Logic relationships
Constraints

Question 2

Types of Logic and relationship Lag

Answer 2

F to S
F to S with pos. lag
F to S with neg. lag
F to F
F to F with lag
S to S

Question 3

When developing logical relationships consider:

Answer 3

Physical limitations: foundations>walls>roof.
Contractual requirements.
Availability of resources or other: limited # of crews available, tight schedule requires concurrent work, most profitable work schedule first.

Question 4

Constraints

Answer 4

Imposed restrictions used to reflect project requirements that cannot be built into the logic.
Aid in building a schedule that more accurately reflects the real world aspects of your project.
Provide added control in the schedule.
Can be abused.
Too many constraints cloud the impact of certain events.
Unnecessary constraints defeat the purpose/value of CPM software.

Question 5

Types of constraints

Answer 5

Date
Duration
Float

Question 6

Typical constraints

Answer 6

Finish no later than:
-Indicates the date by which an activity must finish.
-Affects late dates.
-Used during backward pass.
-Affects the late dates of predecessor activities.
Start on:
-Imposes start-no-earlier-than and start-no-later-than constraint on same activity.

Question 7

CPM theory - forward and backward pass

Answer 7

In: activities, relationships, constraints.
CPM ALGORITHM
Out: Early/Late S and F dates, critical path, float

Question 8

CPM theory - definitions

Answer 8

Early S/F: The earliest an activity can possibly S/F as dictated by all related activities.
Late S/F: The latest an activity must S/F so as not to delay the project.

Question 9

CPM theory - method

Answer 9

Forward pass: calculates early S/F dates
Backward pass: calculates late S/F dates
Total Float: number of days that an activity can be delayed without delaying the end date of the project.
TF= LF-EF
Free Float: amount of time an activity can slip without impacting the early start of successor activities.

Question 10

Critical Path

Answer 10

The longest continuous path of project activities that controls the completion of the project.
On a new schedule the critical path has zero total float.
Delayed project, total float is -.
CPM schedule allows forecasting the effect of changes.
One day of delay to an activity on the critical path causes one day of delay to the project completion.

Question 11

More basic definitions

Answer 11

Milestone: Activity with zero duration.
Constraint: Overrides the calculated date.
Calendar: User defined work and non-work periods.
Hammock: Summary level activities.
Activity code: used to group and organize activities.
Resource and cost loading: Additional project management features.