Chapter 4�Project Time Management

Chapter Objectives

By the end of this chapter students will be able to:

• Understand the importance of good project time management
• Discuss the process of planning schedule management
• Describe how project managers use network diagrams and dependencies to assist in activity sequencing, planning and tracking schedule information, find the critical path for a project
• Describe how critical chain scheduling and the PERT affect schedule development.

Introduction - Importance of Project Schedules

• Managers often cite delivering projects on time as one of their biggest challenges and the main sources of conflict.
• this is because time is easily measured and remembered and can not be debated like scope and budget overruns.
• Time has the least amount of flexibility; it passes no matter what happens on a project.
• Individual work styles and cultural differences cause schedule conflicts.
• some people prefer to follow schedules and meet deadlines while others prefer to keep things open and flexible
• countries may close work for religious or secular holidays
• With all these possibilities for schedule conflicts, it is important for project managers to use good project time management.
• Project time management, simply defined, involves the processes required to ensure timely completion of a project.

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Project Time Management Processes

1. Plan Schedule management: establishing the policies, procedures, and documentation for planning, developing, executing, managing, and controlling the project schedule.
2. Defining activities: identifying the specific activities that the project team members and stakeholders must perform to produce the project deliverables.
3. Sequencing activities: identifying and documenting the relationships between project activities.
4. Estimating activity resources: estimating how many resources a project team should use to perform project activities.
5. Estimating activity durations: estimating the number of work periods that are needed to complete individual activities.
6. Developing the schedule: analyzing activity sequences, activity resource estimates, and activity duration estimates to create the project schedule.
7. Controlling the schedule: controlling and managing changes to the project schedule.
1. ==>the details of these steps are based on project size

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4.1. Plan Schedule Management

• provides guidance and direction on how the project schedule will be managed throughout the project.

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• After reviewing the project management plan, project charter, enterprise environmental factors, and organizational process assets, the project team uses expert judgment, analytical techniques, and meetings to develop the schedule management plan.

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4.2. Defining Activities�

• Activity or task: an element of work normally found on the WBS that has an expected duration, cost, and resource requirements.
• Activity definition involves developing a more detailed WBS and supporting explanations to understand all the work to be done so that you can develop realistic cost and duration estimates.
• helps break down work packages into activities that provide a basis for estimating, scheduling, executing, monitoring, and controlling the project work.
• Project schedules evolve from the project charter which initiated the project. This process of progressive elaboration, as mentioned as a project attribute, is sometimes called rolling wave planning.

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Define Activities: Outputs�

• Activity List: a tabulation of activities to be included on a project schedule that includes the activity name, identifier or number and its brief description.
• Activity Attributes: provide more information such as predecessors, successors, logical relationships, leads and lags, resource requirements, constraints, imposed dates, and assumptions related to the activity.
• The activity list and activity attributes should be in agreement with the WBS and WBS dictionary.
• Milestone List: a list identifying all project milestones that are useful for identifying necessary activities and setting schedule goals and monitoring progress.
• Milestone is a significant event that normally has no duration.
• It often takes several activities and a lot of work to complete a milestone.

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Cont…�

• Examples include
• obtaining customer sign-off on key documents such as design documents and test plans
• completion of specific products such as software modules or installation of new hardware and
• completion of important process-related work, such as project review meetings and tests.
• Not every deliverable or output created for a project is really a milestone. Milestones are the most important and visible events.
• The goal of defining activities is to ensure that the project team has complete understanding of all the work they must do.
• The project schedule should be reviewed with the project stakeholders for acceptance before going to managing the project schedule.

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4.3 Sequencing Activities

• Sequencing activities involves reviewing activities and determining dependencies or relationships.
• a dependency or relationship is the sequencing of project activities or tasks.
• it defines the logical sequence of work to obtain the greatest efficiency given all project constraints.

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Dependency Determination

• Dependency has 4 attributes, but only 2 are applicable at a time.
• Mandatory external and internal dependencies,
• Discretionary external and internal dependencies
• Mandatory dependencies:
• also called hard logic, are those that are legally or contractually required or inherent in the nature of the work being performed on a project.
• For example, you can not test code until it is written
• Discretionary dependencies:
• also called soft logic, are established based on knowledge of best practices within a particular application area or some unusual aspect of the project where a specific sequence is desired.
• They are defined by the project team; and should be used with care since they may limit later scheduling options.

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Cont…

• For example, detailed design may not take place unless the customer signs off for the previous systems analysts work.

3. External dependencies:

• involve relationships between project and non-project activities.
• usually outside the project team’s control.
• Eg, installation of an OS and other software may happen after acquiring a new hardware from an external supplier. Even though delivery of the hardware may not be included in the scope of the project, you should add an external dependency to it because late delivery will affect the project schedule.

4. Internal dependencies:

• involve a precedence relationship between project activities and are generally inside the project team’s control.
• E.g., if the team cannot test a machine until they assemble it.

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Types of Task Dependencies

• You link tasks by defining a dependency between their finish and start dates. 4 types of task dependencies in a project.

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Dependency Examples

• Finish-to-start (FS):
• you cannot provide user training until after a new system has been installed.

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Cont…

• Start-to-start dependency (SS):
• IT projects, a group of activities might start simultaneously, such as the many tasks that occur when a new system goes live
• Finish-to-finish dependency (FF):
• quality control efforts cannot finish before production finishes, although the two activities can be performed at the same time.
• Writing a document is required to finish before editing the document can finish.
• Start-to-finish dependency (SF):
• an organization might strive to stock raw materials just in time for the manufacturing process to begin.
• a delay in starting the manufacturing process should delay completion of stocking the raw materials.
• a babysitter who wants to finish watching a young child must wait the parent to show up or start.

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Sequence Activities: Tools and Techniques �

• Network Diagrams
• a schematic display of the logical relationships among project activities and their sequencing.
• Two formats: the Arrow and Precedence diagramming methods

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Fig 4.1. Sample AOA Network Diagram for Project X

I. Arrow Diagramming Method (ADM)

• Also called activity-on-arrow (AOA) network diagrams
• Activities are represented by arrows
• Nodes or circles are the starting and ending points of activities
• the 1^st node represents the start and the last node the end of a project
• Can only show finish-to-start dependencies
• For a project with hundreds of activities it would be better to include activities only having dependencies on the AOA

Process for Creating AOA Diagrams

• Find all of the activities that start at node 1. Draw their finish nodes and draw arrows between node 1 and those finish nodes. Put the activity letter or name and duration estimate on the associated arrow.
• Continue drawing the network diagram, working from left to right. Look for bursts and merges.

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Cont…

• Bursts occur when a single node is followed by two or more activities. E.g., Node 1 is a burst b/c it goes into Nodes 2, 3, & 4.
• Merge occurs when two or more nodes precede a single node.
• E.g, in the Figure, Node 5 is a merge preceded by Nodes 2 & 3.

3. Continue drawing the project network diagram until all activities are included on the diagram that have dependencies.

4. As a rule of thumb, all arrowheads should face toward the right, and no arrows should cross on an AOA network diagram.

II. Precedence Diagramming Method (PDM)

• Activities are represented by boxes
• Arrows show relationships between activities
• More popular than ADM and used by most PM software
• Better at showing different types of dependencies
• particularly for visualizing certain types of time relationships.

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Fig. 4.2. Sample PDM Network Diagram for Project X�

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4.4 Estimating Activity Resources

• Estimating activity resources is the process of estimating the type and quantities of resources (people, equipment, and materials or supplies) that will be assigned to each activity;
• key benefit: it identifies the type, quantity, and characteristics of resources required to complete the activity which allows more accurate cost and duration estimates.

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Cont…

• Consider important issues in estimating resources
• how difficult will specific activities be on this project?
• what is the organization’s history in doing similar activities?
• are the required resources available?
• could any organizational policies affect the availability of resources?
• would it make sense to outsource some of the work? will outsourcing increase or decrease the amount of resources needed and when they will be available?
• Outputs from this activity include:
• List of activity resource requirements, a resource break down structure, and project document updates
• A resource break down structure is a hierarchical structure that identifies the project’s resources by category and type.

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4.5 Activity Duration Estimating

• provides the amount of time each activity will take to complete.
• Effort is the number of workdays or work hours required to complete a task.
• Duration includes the actual amount of time worked on an activity plus elapsed time. Effort does not normally equal duration.
• People doing the work should help create estimates, and an expert should review them.

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4.6 Developing the Schedule

• Uses results of the other time management processes to determine the start and end date of the project.
• Ultimate goal is to create a realistic project schedule that provides a basis for monitoring project progress.

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Develop the Schedule: Tools and Techniques�Gantt Charts

• Gantt charts provide a standard format for displaying project schedule information by listing project activities and their corresponding start and finish dates in a calendar format.
• Symbols include:
• Black diamonds: milestones
• Thick black bars: summary tasks
• Lighter horizontal bars: durations of tasks
• Arrows: dependencies between tasks

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Figure 4.3. Gantt Chart for Project X

Figure 4.4 Gantt Chart for Software Launch Project

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Adding Milestones to Gantt Charts

• Many people like to focus on meeting milestones, especially for large projects.
• Milestones emphasize important events or accomplishments on projects.
• Normally create milestone by entering tasks with a zero duration, or you can mark any task as a milestone.

SMART Criteria

• Milestones should be:
• Specific
• Measurable
• Assignable
• Realistic
• Time-framed

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E.g, distributing a marketing plan is specific, measurable, and assignable if everyone knows what should be in the marketing plan, how it should be distributed, how many copies should be distributed and to whom, and who is responsible for the actual delivery. Distributing the marketing plan is realistic and able to be time-framed if it is an achievable event and scheduled at an appropriate time.

Best Practice

• Schedule risk is inherent in the development of complex systems.
• project managers can reduce schedule risk through project milestones, a best practice that involves identifying and tracking significant points or achievements in the project.
• The five key points of using project milestones include:
• Define milestones early in the project and include them in the Gantt chart to provide a visual guide.
• Keep milestones small and frequent.
• The set of milestones must be all-encompassing.
• Each milestone must be binary, meaning it is either complete or incomplete.
• Carefully monitor the critical path.

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Figure 4.5 Sample Tracking Gantt Chart

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Critical Path Method (CPM)

• CPM is a network diagramming technique used to predict total project duration.
• The critical path is the longest path in the network diagram
• the CP has the longest duration, and its duration is known as the duration of the project.
• activities on the CP have no float or slack, so no activity should be delayed. If this happens, the project will be delayed.
• A critical path for a project is also the series of activities that determines the earliest time (shortest duration) by which the project can be completed.
• There can be more than one CP if the lengths of two or more paths are the same.
• The CP is not the one with all the critical activities; it only accounts for time & it can change as the project progresses.

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Cont…

• Calculating the Critical Path
• First develop a good network diagram
• Add the duration estimates for all activities on each path through the network diagram
• The longest path is the critical path
• What does the critical path really mean?
• Normally, several tasks are done in parallel on projects, and most projects have multiple paths through a network diagram.
• The longest path or the path that contains the critical tasks is what drives the completion date for the project. You are not finished with the project until you have finished all the tasks.
• The CP, thus represents the shortest time required to complete a project.
• If one or more activities on the CP take longer than planned, the whole project schedule will slip unless the project manager takes corrective action.

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Figure 4.6 Determining the Critical Path for Project X

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Using CP Analysis to make Schedule Trade-offs

• Project managers make schedule trade-offs by determining the free slack and total slack for each project activity.
• Free slack or free float is the amount of time an activity can be delayed without delaying the early start of any immediately following activities.
• Free float = ES_{next activity} – EF_{current activity}
• Total slack or total float is the amount of time an activity may be delayed from its early start without delaying the planned project finish date.
• Total float= LS – ES or LF – EF
• A forward pass through the network diagram determines the early start and finish dates for each activity.
• A backward pass determines the late start and finish dates for each activity.

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Table: Free and Total Float/Slack for Project X

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NB: If activities that are not on the CP have a difference between their ES and LS, they can be delayed without affecting the project completion date.

How to Find the Critical Path

• To find the critical path, you need to determine the following
• Earliest start time (ES): the earliest time an activity can begin without violation of immediate predecessor requirements
• Earliest finish time (EF): the earliest time at which an activity can end.
• Latest start time (LS): the latest time an activity can begin without delaying the entire project.
• Latest finish time (LF): the latest time an activity can end without delaying the entire project.

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• Earliest times are computed as
• Earliest finish time = Earliest start time + Expected activity time. EF = ES + t
• Earliest start time = Largest of the earliest finish times of� immediate predecessors

ES = Largest EF of immediate predecessors

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• In the nodes, the activity time, the early and late start and finish times are represented-->

Example

• Precedence table for activities involved in General Foundry’s project is given below:

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• Draw the activity network diagram that models the project
• Calculate the early start and finish dates
• Calculate the late start and finish dates
• State the critical path
• Find the free float on activity D and
• what is the effect on the project end date if Task G starts two days late?

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• Calculating Earliest Times
• begin with the project start date and assign that date as the start date of activities that have no predecessor.
• Thus ES = 0 for both A and B
• to calculate the ES dates of subsequent activities:
• Add the predecessor activity’s duration to its start date.
• Add the lag time or subtract the lead time.
• Add the number of off-days an activity would span on resource calendars
• Assign the largest of the EF times of immediate predecessors as the ES date of the successor activity.

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Then EF= ES+ t

• EF for A=0+2=2;
• EF for B=0+3=3

Cont…

General Foundry’s ES and EF times

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• A forward pass through the network diagram determines the early start and finish dates for each activity.

ES of successor activity is the largest EF of immediate predecessors.

Cont…

• Latest times computations
• Latest start time = Latest finish time - Expected activity time

LS = LF - t

• Latest finish time = Smallest of latest start times of� following activities

LF = Smallest LS of following activities

• begin with the project completion milestone and assign that date as the finish date of its predecessor activities.
• to calculate the LS dates of predecessor activities:
• Subtract the predecessor activity’s duration from its LF.
• Subtract the lag time or add the lead time to the LF.
• Subtract the number of off days an activity would span on resource calendars
• Assign the smallest of the LS times of following activities as the LF date of the predecessor activity.

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Cont…

• For activity H:
• LS = LF – t = 15 – 2 = 13 weeks
• A backward pass through the network diagram determines the late start and late finish dates for each activity in a similar fashion.

General Foundry’s LS and LF times

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Cont…

• Once ES, LS, EF, and LF have been determined, it is a simple matter to find the amount of slack time that each activity has

Slack = LS – ES, or Slack = LF – EF

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• From previous Table, activities A, C, E, G, and H have no slack time and are called critical activities and they are said to be on the critical path. The total project completion time is 15 weeks
• Industrial managers call this a boundary timetable.

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Critical Activities

Schedule Compression/ Shortening Using CP

• Fast tracking activities involves doing activities in parallel or overlapping them that you would normally do in sequence.
• It only works if activities can be overlapped to shorten the project duration.
• E.g., instead of waiting for all analysis to be completed before starting coding, some coding could begin for those tasks that have been fully analyzed.
• The main disadvantage is that it can lengthen schedule of the project because starting some tasks too soon often increases project risk and results in rework.
• other tasks whose analysis has not been completed could impact a task and cause rework.
• Crashing activities by obtaining the greatest amount of schedule compression for the least incremental cost.

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Cont…

• A 2 week task with one person working 50% could be shortened to 1 week if the person is assigned 100% - no increase in cost
• Or, a temporary worker could be hired to work in parallel with the other worker to speed up the task (at a cost)
• By adding resources
• approving overtime, bringing in additional resources, or paying to expedite delivery to activities on the critical path etc.
• it works only for activities on the critical path where additional resources will shorten the activity’s duration.
• It does not always produce a viable alternative and may result in increased risk and/or cost.

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Critical Chain Scheduling

• Critical chain scheduling (CCS)
• a scheduling method that allows to place buffers to protect the project completion date on any project schedule path to account for limited resources and uncertainties.
• attempts to minimize multitasking
• Someone assigned to three tasks, tries to please everyone and works a little on each task and then goes back to finish the first one. This can actually delay the completion of tasks as compared to working on each task in sequence, it also often involves wasted setup time, which increases total duration.

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Buffers and Critical Chain

• In traditional estimates, people often add a buffer to each task and use it if it’s needed or not
• a buffer is additional time to complete a task
• this time is added to when there is multitasking, distractions, interruptions, fear that estimates will be reduced
• CCS removes buffers from individual tasks and instead adds duration buffers that are non-work schedule activities to manage uncertainty:
• A project buffer placed at the end of the critical chain and protects the target finish date from slippage along the critical chain (the resource-constrained critical path).
• Feeding buffers placed at each point where a chain of dependent activities that are not on the critical chain feeds into the critical chain.
• protect the critical chain from slippage along the feeding chains.

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Cont…

• The tasks estimates in CCS should be shorter than traditional estimates because they do not include their own buffers
• Feeding and project buffers protect the date that really needs to be met – the project completion date

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Figure Example of CCS

Example of Critical Chain Scheduling

Critical Path = Task1+Task2+Task3+Lag+Task6 = 6+4+2+1+8 = 21 Days.

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Program Evaluation & Review Technique (PERT)

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4.7 Schedule Control

• monitoring the status of project activities to update project progress and manage changes to the schedule baseline to achieve the plan.

Schedule Control Suggestions

• perform reality checks on schedules
• allow for contingencies

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Cont…

• Don’t plan for everyone to work at 100% capacity all the time
• Hold progress meetings with stakeholders and be clear and honest in communicating schedule issues
• Goals are to know the status of the schedule, influence factors that cause schedule changes, determine that the schedule has changed, and manage changes when they occur.
• Reality Checks on Scheduling
• First review the draft schedule or estimated completion date in the project charter
• Prepare a more detailed schedule with the project team
• Make sure the schedule is realistic and followed
• Alert top management well in advance if there are schedule problems
• Verify schedule progress – just because a team member says a task was completed on time doesn’t always mean that it was

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Discussion Questions�

1. Why schedule issues often cause the most conflicts on projects?
2. Why is defining activities a process of project time management instead of project scope management?
3. Why is it important to determine activity sequencing?
4. How does activity resource estimating affect estimating activity durations?
5. Explain the difference between estimating activity durations and estimating the effort required to perform an activity.
6. Explain the following schedule development tools and concepts: Gantt charts, CP method, PERT, and critical chain scheduling.
7. What do you think about adding slack to individual task estimates (sometimes called padding estimates)? What do you think about adding a project buffer for the entire project, as CCS suggests? What are some ethical considerations when using slack and buffers?
8. How can you minimize or control changes to project schedules?

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