Lesson 3: Project Scope Management: LINK

4. Project time management

4. Project time management

4.1 Project time management

4.2 Project activity definition and activity sequencing

4.3 Project activity duration estimation

4.4 Resource estimation

4.5 Rolling wave planning

4.6 Project schedule development

4.7 Critical path PM (CPM)

4.8 WBS

4.9 Use of Gantt chart

4.10 Project schedule control

4.1. Project time management

Act of planning, controlling, and executing specific activities, to increase efficiency and productivity.

It consists of 5 main phases as per PMBOK:

  1. Activity definition – establish the activities necessary to product the deliverables
  2. Activity sequencing – establish the dependencies between these activities
  3. Activity duration estimating – estimate the effort of work necessary to complete the tasks
  4. Schedule development – create the project schedule based on above estimates and on the necessary resources
  5. Schedule control – control the changes made to the schedule

4.2 Project activity definition and activity sequencing

Project activity definition

Activity definition will identify the deliverables at the lowest level in the WBS called the work package. Work packages are decomposed into smaller components called schedule activities to provide a basis for estimating, scheduling, executing, and monitoring+controlling project work.

Activity definitions rely on specific input processes like enterprise environmental factors, organisational process assets, project scope statement, the breakdown structure, the WBS dictionary, the PM plan that includes both schedule management and scope management plan.

The important outputs of it are: activity list, the resulting activity attributes, all requested changes, and any milestones.

Project activity sequencing

Reviews all activities in the WBS to identify relationships between them, and classifying all dependencies.

Dependencies can be external like unavailability of a new version of the tool in the market – or internal, like unavailability of a developer for the complete project.

Once all dependencies have been identified, a network diagram can be created to schematically show the sequencing of projects. In network diagrams, arrows represent tasks and are drawn to show dependencies. The completed network diagram can be used to identify the critical path of a project – the series of dependent activities that determine the  shortest possible duration of the project. To find the critical path, trace all paths represented by arrows through the network while summing the duration of all tasks.

Tools and techniques for activity sequencing

Precedence diagramming method (PDM)

Construct a network diagram using nodes to represent activities and connect them with arrows to show dependencies.

[Start] => [Phase1] => [Phase2] => [Finish]

This is a very simplistic representation of PDM. It is also called Activity-on Node (AON).

Dependencies are important as they show the direction (sequence) in which activities should occur.

There are 4 types of activity sequencing designs:

  • Finish-to-start relationship: if one activity must finish for another activity to start
  • Start-to-finish relationship: if one activity must start before another can finish
  • Start-to-start relationship: if one activity cannot start until another activity starts
  • Finish-to-finish relationship: if one activity cannot finish until another activity finishes

Arrow diagram method (ADM)

Construct a project network diagram using arrows for representing activities and connecting them at nodes to show dependencies. It is knows as Activity on Arrow and is less common than PDM.

Conditional diagramming methods

GERT (Graphical Evaluation and Review Technique) and System Dynamics models allow for non-sequential activities such as loops and conditional branches. Neither PDM nor ADM allows for these.

4.3 Project Activity Duration Estimation

The estimated project duration is based on sum of the activities. For an accurate estimation, several other factors need to be taken into account:

  • Constraints: Anything that restricts a project. Example: a developers vacation.
  • Assumptions: Need to be documented
  • Law of diminishing returns: Controls yields vs amount of labor available. Not all activities are effort-driven and many are of fixed duration. Hence, adding more programmers would not always mean reduced time.
  • Parkinson’s Law: States that work expands to fill the amount of time allowed.
  • Risks: Business risks can delay project work, need to be taken into account.

4.4. Resource Estimation

This process associates activities with the resources required to accomplish the work. It lists each type and amount, or quantity, of each required resource.

Activity resources can include:

  • Equipment
  • Material and supplies
  • Money
  • People

The inputs of resource estimation process are:

  • Enterprise environmental factors
  • Organisational process assets
  • Activity list
  • Activity attributes
  • Resource availability
  • Project management plan

The tools and techniques used for estimation are:

  • Expert judgement
  • Alternative analysis
  • Published estimating data
  • Project management software
  • Bottom-up estimating

The outputs are:

  • Activity resource requirements
  • Activity attributes (updates)
  • Resource breakdown structure
  • Resource calendar (updates)
  • Requested changes

4.5 Rolling wave planning

“It is not often possible to force the future activities in a project with consistent detail of the entire period. Therefore, planning is done in “waves” or stages, with the activities in the near term planned in detail and the activities in longer term left for future detailed planning. There may be in fact several planning waves, particularly if precise approach or resource requirement is dependant or conditioned on the near-term activities.”

– John Goodpasture

  • RWP is a technique that enables you to plan for a project as it unfolds. ie. to plan iteratively using Agile. You plan until you have visibility, implement, and then re-plan.
  • Example: If a project is expected to complete in 8 months, but we only have clarity for the first 3 months. Then, we would plan only for 3 months. This technique uses progressive elaboration.
  • However, it is necessary to prove key milestones and assumptions for the entire project for stakeholders to see why we are using RWP and what to expect.

When is it used?

It is used when we don’t have just enough clarity to plan the entire project. This lack of clarity could come from factors such as emerging requirements and high uncertainty. In product dev, a common practice is to prototype before actual product dev., in such cases RWP can be used to plan the prototype and then plan again.

4.6 Project Schedule Development


  • Schedule tells when each task is to be done, what has been done, and the sequence of tasks.
  • It is part estimation, part prediction, and part ‘educated guessing’, it’s not an exact process.
  • Because of the uncertainty, it is to be reviewed and continues to develop as the project moved forward.


  • Provide a basis to monitor + control activity
  • Determine best resource allocation based on goals
  • To access time delay impacts
  • To check where excess resources are available
  • Provide a basis to track project progress

Schedule inputs:

  • Personal & project calendars
  • Description of project scope
  • Project risks
  • Activity and resource requirements

Scheduling tools:

  • Schedule network analysis – graphical representation of project activities – using Gantt charts & PERT charts
  • Critical path analysis – to check min time for completion
  • Schedule compression – by decreasing the time for project activities
  • Crashing – more resources to decrease time where possible
  • Fast -tracking – rearranging activities to allow parallel work where possible

Use of project stages:

  • Projects over-run mostly because of the final polishing and error correction taking a much longer time than expected.
  • To avoid this, schedule projects in distinct stages, where final quality, finished components are delivered at the end of each stage in order to fix quality issues early on.

Project review:

  • ‘What if’ scenario analysis – risk plan based on what if questions like what if x person goes on leave, etc
  • Resource leveling – rearrange the sequence of activities to address the possibility of unavailable resources and to make sure excessive demand is not put on resources at a given time
  • Critical chain method – Extra time between activities added to manage work disruptions
  • Risk multipliers – Add extra time for high-risk activities and add time multipliers to certain tasks or resources

4.7 Critical Path Project Management (CPM)

  • When all asks are listed and sequenced, some tasks have little flexibility in their start and finish date. This is called float. Others have no flexibility, called zero float.
  • A line through all the tasks with zero float is called the critical path. All tasks on this path must be completed on time if the project is to be completed on time. Note that there can be multiple, parallel paths.
  • The PMs key task is to manage the critical path, and to do an effective critical path analysis before starting. Note that items can be added or removed from the critical path during the execution of the project if circumstances change.

PERT: Project Evaluation & Review Technique – started by US Navy is a variant of critical path analysis & is used for very large-scale, one-time, complex, non-routine infra and R&D projects.

CPA helps in:

  • what tasks to do
  • where parallel activity can be performed
  • shortest time in which the project can be completed
  • resources needed to execute the project
  • sequence of activities, scheduling, and timings
  • Task priorities
  • Most efficient way of shortening time on urgent projects

How to find the critical path:

Start with the earliest / first task > see what tasks can’t start until that one is finished > then pick the longest of these tasks and it will be the next task in the critical path > now figure what tasks depend on the completion of that 2nd task and pick the longest of them to become the 3rd task > continue until reaching end of the project.

Note that the critical path is not the path with most imp tasks but the ones which will cause project delay if they’re delayed. CPM is used to manage the project and deliver it on time using the critical path.

4.8 Work Breakdown Structure

The WBS is a deliverables-oriented decomposition of the project – Of the project deliverables and not the project tasks – the tasks can be performed based on the deliverables identified in the WBS

The WBS should conform to the 8/80 rule i.e. smallest element in the WBS called the work package should be between 8 and 80 hours of work.

4.9 Use of Gantt Chart

A type of bar chart which illustrates start and finish dates or terminal elements and summary elements of a project.

  • Terminal and summary elements comprise the WBS of the project.
  • It is useful for small projects that can fit on a single screen and have less than 30 activities. This is because they communicate little info per unit area of display.
  • The main focus is on schedule management and hence they only represent a part of the triple constraints.
  • The horizontal bars of a Gantt have fixed height, hence can misrepresent the  resource requirements of a project, causing confusion esp. in large projects.

4.10 Project Schedule Control

The key to effective PM is to measure actual progress and compare it to planned progress on a timely and regular basis to take necessary corrective action immediately.

A baseline plan, agreed with customer, should have been est. first and reporting should be done daily / weekly / monthly depending on the complexity and duration of the project with –

  • Data on actual performance
  • Information on any changes to scope, schedule or budget

The project control process continues throughout the project.

Approach to schedule control – includes 4 steps:

1. Analyse schedule to determine areas which need corrective action

2. Decide specific corrective actions

3. Revise the plan to incorporate the chosen corrective action

4. Recalculate the schedule to evaluate efforts of the planned corrective action

Repeat these steps if planned corrective action does not result in an acceptable schedule.