Project Scheduling?

Why scheduling?

Extracted and summarised from the PMI Practice Standard for Scheduling - Third Edition- 2019

Projects are complex temporary endeavours however, a detailed schedule model that contains logically related work allows the project to be simplified into manageable phases or groups of activities.

These phases or groupings allow management to optimise the trade-offs between scope cost and schedule. The execution of a project often proceeds differently than the initial plan and baseline.

This interactive evolution is required to predict, recognise, and address those evolving factors and issues that could potentially affect project performance.

Project scheduling ensures the development of effective schedule modules through the application of skills, tools, techniques and intuition acquired through knowledge, formal and informal training and experience.

Milestone is a significant point or event in a project to find with the duration of Zero time periods

Activity a distinct schedule portion of work performed during the course of a project and activity is a unique distinct schedule portion of work with a duration greater than 0 times to be performed during the course of a project.

Resource - skilled human resource or equipment services supplies commodities materials budgets or funds required to accomplish the defined work.

Logical relationship -.  a dependency between two activities over between and activity and a milestone.

The schedule model supports the project by allowing for:

•  time phasing of required activities

•  constraints that limit the options for managing a portfolio program project or process

•  resource planning

•  mobilisation of plan resources in a most efficient manner

•  coordination of events within the project and among other projects

•  visual representation of these schedule issues to the stakeholders

•  early detection of risks problems issues or opportunities

•  implementation of actions to achieve the project of objectives as planned

•  what if and variants analysis

•  cost planning

•  forecasting of estimate a complete and to complete

Critical Path approach

 CPM refers to the prevalent approach used in modern scheduling tools and helps to identify the shortest time to complete the project.  The Critical Path approach is used to derive the critical activities that cannot be delayed without delaying the end of the project.

 CPM determines the minimum total project duration and earliest possible finish date of the Project. CPM also determines the amount of scheduling flexibility also known as total float (TF) in the schedule model.

 location based scheduling

Location-based scheduling (LBS) was developed to help project managers in the construction industry with workflows and planning. LBS is also known as vertical production method, linear scheduling, repetitive scheduling method and Flowline scheduling. This approach focuses on optimising production rates for many resources while working in parallel, often on multiple work fronts.

Lean scheduling

Lean scheduling is based on the principles of lean project delivery (on demand scheduling) and designed to minimise waste in order to maximize value. To achieve this goal, deliverables and not assigned to the team. Lean scheduling principles point to the importance of limiting queues by pulling work when there is capacity to place the work into the process.

 Line of balance

The line of balance (LOB)  was initially developed for planning and controlling manufacturing industrial processes. later, it's use was  expanded as a method for planning and controlling projects with repetitive or long duration activities. Line of balance focus is on production rates over time, rather than on defining and tracking discreet activities over time. This results in a visualization that shows the flow of work and units produced.

LOB shows repetitive work in the project as a single line on a graph rather than a series of individual activities on a Barchart. 

This line represents the rate that the work needs to be performed to stay on schedule. LOB can help expose process bottlenecks. The main advantage of the LOB is that it calculates productively along with time in an easy graphical representation.

Building Information modeling (BIM)

Building Information modeling is a process that creates and manages information regarding the physical and functional characteristics of a building. It is used to support decision-making during the buildings entire life cycle.

The collection of project information in a central repository provides an opportunity to integrate the projects 3D model and the schedule model. BIM software allows identification of sequences for  the design of objects which become the underlying logic for the schedule.

Scheduling tool

A scheduling tool is typically a software application that contains algorithms, components, features, and rules to input and manipulate activities, dependencies, resources, and their assignments to create schedule model instances and schedule presentations.

Schedule model

 the schedule model is guided by a schedule management plan that identifies :

a) scheduling approach used

b)  the scheduling tool used

c)  how the activities, planned dates, durations, resources, dependencies, and constraints should be addressed.

If historical data is available, this should be considered in determining duration. constraints,

Including lead and lag time factors, should not be used in the schedule model to replace schedule logic.

 Schedule management plan

 the schedule management plan is a collection of processes, approaches, templates, and tools that comprise the project's execution strategy and objectives as reflected in the projects schedule model.  The schedule management plan is unique to each project and is comprised of requirements defined by the implementing organisation as well as the project scope of documents. The schedule management plan defines how the schedule model will be developed, updated, progressed, and shared. 

Key components of the schedule management plan

•  scheduling approach

•  scheduling tool

•  schedule model creation plan

•  schedule model identification

•  schedule model instance

•  calendars and work periods

•  project updates cycle and activity granularity

•  Milestone and activity coding structure

•  resource planning

•  key performance indicators

•  change control

Schedule model creation

The schedule model describes;

•  work to be done

•  resources required to do the work

•  activity durations based on resource availability and productivity

•  optimum activity sequence based on logical relationships between schedule activities, resource availability, and calendars.

work to be done -  ensure that the project will quite requirements are understood and satisfied

verify resource availability and assignments

define milestones -  once there is an understanding of the overall structure for the project data, begin to lay out the project's milestones.

A milestone has zero duration, there's no resources assigned, and is used as a benchmark to measure progress, and my also reflect the Start and finish points for various project events. 

Generally a milestone represents the start or completion of a portion of a deliverable of the project. It may also be associated with external constraints, such as delivery of specific required approvals or deliverables..

Defining the projects activities - create a list of activities that need to be performed to complete the project.

The characteristics of a well-defined activity include: activity owner, activity descriptions, continuity of work activity, activity duration.

Crashing the schedule

 crashing consists of adding resources to critical activities to shorten durations or spending money in other ways to reduce the length of activities when adding resources to reduce activity duration. Crashing only works for activities that  are  effort driven. Crashing should only be performed on activities on the Critical Path and then, on only those activities that yield the most cost-effective result. Crashing typically increases project costs by some factor

Fast Tracking

Fast tracking consists of changing the logic for overlapping critical activities rather than working them strictly in sequence. Fast tracking increases the risk of rework because the activity is started before they initial predecessors are completed and possibly contributes to an increased number of change orders on contracted work

Schedule levels

Level 0 -  project summary -  this is a single line representing the entire project and is often used for comparing projects in a program or portfolio audiences for this schedule level include, but not limited to command strategic partners command senior executives, portfolio or program managers, and operation managers

Level 1 -  executive summary -  this report is a higher level schedule that includes key milestones and summary activities by major phase, stage, or project being executed. it is typically represented in Bar chart format and may originate in a table of key elements or a graphic. level 1 schedules provide high level information assists in the decision-making process. audiences for this schedule level include and not limited to customers senior executives and general managers

Level 2 -  management summary -  this report is generally prepared to communicate the integration of work throughout the life cycle of a project.  level two schedules my reflect interfaces between key deliverables and project participants which are required to complete the identified deliverables for stop typically presented in Bar chart format.  this is rolled up from a more detailed schedule.  Holdings for this toughest schedule include but not limited to customers general managers sponsors and program or project managers

Level 3 -  publications schedule - this report is generally prepared to communicate the execution of the deliverables for each of the contracting parties. the schedule should reflect interfaces between keyword groups disciplines for crafts involved in execution of the project in a voucher or CPM network format.

Level 4 -  execution planning - this visual should reflect indices between k elements that drive the completion effectivity to typically presented in voucher or CPM network format and usually provide enough detail to plan accordingly multi  discipline activities. The period covered by a level 4 layout or report is usually one week to one month and supports the milestones and durations represented in a level three schedule

Level 5 - detailed planning -  this report is prepared to communicate task requirements for completing activities or identified in a detailed schedule. a level 5 schedule is usually considered a working schedule that reflects hourly daily or weekly work requirements. depending on these requirements level five schedules are usually prepared one day or one weekend advance. the period covered by a level 5 layer usually one day to one week supporting the milestones &  durations represented in the level three or four schedules.

Schedule model maintenance

•  collect actuals and remaining work or duration

•  update the schedule model according to the actuals

•  compare and address any deviation

•  update the schedule model with approved changes

•  update the baselines schedule model

•  Communicate

•  maintain the records

•  change control

schedule model and analysis -  the primary objective of the analysis is the early identification of threats and opportunities to the project objectives.

Critical Path -  the projects Critical Path is one of the key components to understand project performance and accurately monitor its forecasted movements, based on inputs made over time to the project.

The Critical Path is the sequence of activities that predicts or define the longest path and shortest duration for the project.  The Critical Path is the longest path through the project, starting at the earliest milestone and project completion. The Critical Path determines the duration of The Project. to critical half calculations consider activities and constraints to determine the longest path in the project. However, a Critical Path can end for example on a schedule Milestone that occurs at any point within the schedule model and that has a finish no later than constraint. 

Critical activities

It is important to distinguish between Critical Path activities and critical activities.  Critical Path activities are those activities contained in the Critical Path or paths.

Critical activities - those activities vital to the success of a project, even when they do not appear on the ‘critical path’. These can be high risk in terms of scope, schedule, resources, safety. Environment, cost and can cause a delay in the project end date.

Total Float & Free Float

• Free Float (FF) represents the amount of time an activities early finish date may be delayed without affecting any successor activities early start date. FF is relevant to an individual activity.

• Total Float (TF) represents the amount of time an activities early start date or early finish date may be delayed without impacting the project finish date.

• Changes to TF indicate a threat to achieving project completion

• Changes to FF indicate a lack of progress, which may impact successor activities

Estimation of Activity durations

When there is a great deal of uncertainty in activity duration, a commonly used estimating technique is the three-point estimate. The three points are based on optimistic, pessimistic and most likely durations. PERT : Program Evaluation & Review Technique = [optimistic duration + 4x most likely duration + pessimistic duration]/6

• Optimistic duration - the minimum activity duration, occurring under the most favourable conditions

• Most likely duration - the activity duration that will occur most often

• Pessimistic duration - the maximum activity duration that will occur under the least favourable conditions.

Date Constraints

• Date constraints restrict the ‘free flow’ of the activity logic and the ability of the schedule to react to changes. Constraints can also disregard risks and impact the usefulness of Schedule Risk Analysis.

• When a date constraint becomes necessary, more flexible constraints are preferred.

Open Ended activities

• Activities without predecessor and/or Successor

• Create a false appearance of float

• Reduces impact of risk or change

• Results in questionable validity of the schedule

• Questionable Critical Path

Out of sequence (OOS) logic

• Occurs when reporting progress.

• An activity starts, ignoring its predecessor/s. Ie ignoring logic relationship.

• Is the logic correct

• Does the predecessor task have to be completed?

Leads & Lags

• Lead - a relationship that allows acceleration of the successor activity

  • Shown as a negative value

• Lag  - a relationship that imposes a delay of the successor activity

  • Shown as a positive value

Start to Finish relationship

• Activity logic that involves the circumstance of a successor task occurring before its logical predecessor

Links to/from Summary activities

• Not recommended as the logic can be difficult to follow/trace.

• Using links to summary tasks may produce logic errors or create circular logic

Schedule Risk Analysis/Assessment

• Used to validate schedules (completion dates, contingency periods)

• PERT does not recognise logic paths

• Monte Carlo simulations for numerous schedule simulations/iterations

• Risk inputs are modeled and a probabilistic completion date is calculated

Earned Value Method (EVM)

EVM is a method for calculating schedule variances, performance, and likely outcomes given current performance.

• Associated with time-based analysis

• Provides an accurate understanding of the cost

• Provides various indicators and indices

Communication & Reporting

Clear communication of the schedule/performance builds credibility for stakeholders

• Critical path reports

• WBS reports

• Weekly/Monthy detailed schedules

• Resource Report

• Dependencies reports

• Critical Issues report

• Schedule risks report

• Progress Reports

• Quantity Reports

• Visual Dashboards