Project Time Management

This chapter covers key concepts related to Project Time Management.
The knowledge area of Project Time Management consists of the following processes -

Time Management Processes

Process	Project Phase	Key Deliverables
Define Activities	Planning	Activity List, Milestone list
Sequence Activities	Planning	Project Schedule network diagrams
Estimate Activity Resources	Planning	Activity resource requirements, Resource breakdown structure
Estimate Activity Durations	Planning	Activity duration estimates
Develop Schedule	Planning	Project Schedule
Control Schedule	Monitoring and Controlling	Work Performance measurements, Change Requests

class="basic" The Define Activities process has the following Inputs, Tools and Techniques and Outputs -

Define Activities Process

Inputs	Tools and Techniques	Outputs
Scope baseline	Decomposition	Activity list
Enterprise environmental factors	Rolling wave planning	Activity attributes
Organizational process assets	Templates	Milestone list
	Expert judgment

The Sequence Activities process has the following Inputs, Tools and Techniques and Outputs -

Sequence Activities Process

Inputs	Tools and Techniques	Outputs
Project scope statement	Precedence diagram method (PDM) or AON	Project schedule network diagrams
Activity List	Applying leads and lags	Project document updates
Activity attributes	Schedule Network Templates
Milestone list	Dependency determination
Organizational process assets

The Estimate Activity Resources process has the following Inputs, Tools and Techniques and Outputs -

Estimate Activity Resources Process

Inputs	Tools and Techniques	Outputs
Activity List	Expert judgment	Activity resource requirements
Activity attributes	Alternative analysis	Resource breakdown structure
Resource calendars	Published estimating data	Project document updates
Enterprise environmental factors	Bottom-up estimating
Organizational process assets	Project Management software

The Estimate Activity Durations process has the following Inputs, Tools and Techniques and Outputs -

Estimate Activity Durations Process

Inputs	Tools and Techniques	Outputs
Activity list	Expert judgment	Activity duration estimates
Activity attributes	Analogous estimating	Project document updates
Activity resource requirements	Parametric estimating
Resource calendars	Three-point estimates
Project scope statement	Reserve analysis
Enterprise environmental factors
Organizational process assets

The Develop Schedule process has the following Inputs, Tools and Techniques, and Outputs-

Develop Schedule Process

Inputs	Tools and Techniques	Outputs
Organizational process assets	Schedule network analysis	Project Schedule
Project scope statement	Critical path method	Schedule baseline
Activity List	Schedule Compression	Schedule data
Activity attributes	What-if scenario analysis	Project document updates
Project Schedule Network diagram	Resource levelling
Activity Resource requirements	Critical chain method
Resource Calendars	Scheduling tool
Activity duration estimates	Applying calendars
Project Management Plan - Risk Register	Adjusting Leads and Lags
Enterprise environmental factors

The Control Schedule process has the following Inputs, Tools and Techniques and Outputs -

Control Schedule Process

Inputs	Tools and Techniques	Outputs
Project management plan	Performance reviews	Work performance measurements
Project schedule	Variance analysis	Organizational process assets updates
Work performance information	Project management software	Change requests
Organizational process assets	Resource leveling	Project management plan updates
	What-if scenario analysis	Project document updates
	Adjusting leads and lags
	Schedule compression
	Scheduling tool

Bar charts (or Gantt charts) are used to display tasks and their dates in a graphical fashion. They are used to display information of the type task 1 is scheduled from date A to date B. Typically the date range is displayed in the X-axis and the tasks on the Y-axis. Bar charts do not show task dependencies. They are generally used to track progress and show to the team.
Milestone charts are similar to bar charts but display only major events. They display major milestones (for example bridge design completed). They are used to report status to Management.
Network diagrams are used to display activities and their dependencies. Network diagrams can be used to perform critical path analysis. Network diagrams can also be used to perform crashing and fast tracking of the project. 
There are two type of network diagrams -

• Activities on Node (or Precedence)
• Activities on Arrow (or AOA)

Precedence is most commonly used. AON and AOA cannot have loops or conditional relationships.
An activity in a network diagram is displayed as shown below.

Activity name
class="basic"Activity Number	Estimate

As an example -

Documentation
2	5 days

In the above example Documentation is activity number 2 and is estimated to last 5 days.
Precedence (or Activity on Node) diagrams can be used to display four type of relationship between activities. These are

• Finish-To-Start
• Start-To-Start
• Start-To-Finish
• Finish-To-Finish

Finish-to-start relationship means the dependent activity cannot start until the first activity is finished. This is the most common way to represent relationships between activities.

Activity on Array (AOA) network diagrams have the following characteristics.

• AOA only uses Finish-To-Start relationship between tasks.
• PERT and CPM can only be used with AOA.
• Dummy events are shown with dotted lines. They do not take any time. They show dependencies between tasks.

Longest path through the network diagram is called the critical path. The activities on the critical paths are called critical activities.
Lags are inserted waiting times in between tasks. For example Task B cannot start until three days after task A completes.
Slack or Float is the amount of time a task can be delayed without delaying the project. Tasks on the critical path have zero float.
Critical Path Method (CPM) has the following characteristics.

• It uses one time estimate per activity
• It can be drawn only using AOA diagrams
• It can have dummy events

Program Evaluation and Review Technique (PERT) has the following characteristics.

• It uses three estimates per activity - optimistic, pessimistic and most likely
• It can be drawn only using AOA diagrams
• It can have dummy events

PERT utilizes more information than CPM as it considers the "Pessimistic" and "Optimistic" values in addition to the "Most Likely" value in its calculations. The following are formulae used by PERT -
 Mean = (P + 4M + O)/6
 Standard Deviation = (P-O)/6
 Variance = ((P-O)/6)2 
Here P is the pessimistic estimate, O is the optimistic estimate and M is the most likely estimate.
GERT is another type of network diagram. It can support looping.
If a project has more than one critical paths then the risk to the project increases.
Resource levelling refers to keeping the resources same across the duration of the project.