Introduction to Schedule management
Schedule management is the process of developing, maintaining and communicating schedules for time and resource.
A schedule is the timetable for a project, programme or portfolio. It shows how the work will progress over a period of time and takes into account factors such as limited resources and estimating uncertainty.
The scheduling process starts with the work that is needed to deliver stakeholder requirements. This includes the technical work that creates outputs, the change management work that delivers benefits, and the management activity that handles aspects such as risk management and stakeholder management.
Some types of work can be defined much more easily than other types. The work involved in building a house is clear from the start. The work involved in maintaining a generator is not clear until inspections are complete.Engineering work tends to have complete specifications from the start, whereas change management and some IT work follow a more iterative approach to defining what needs to be done.
Approaches to calculating schedules have to be equally flexible. In some cases, rigorous techniques can be used to model the work and calculate detailed timings. In other cases, broad estimates have to be made initially, with constant refinement as more information becomes available.
A detailed model can be used to perform ‘what-if’ calculations to test the result of potential events (e.g. ‘What if resource x is not available in February?’, or ‘What if there is adverse weather in March?’).
The detailed and high-level scheduling approaches are both combined in ‘rolling wave’ scheduling. Short-term work is typically the best defined and can be subject to the most rigorous scheduling. Longer-term work is more vague and subject to change. The window of detail moves along the schedule like a rolling wave.
Schedules are presented in many different ways in order to suit the circumstances. The choice of presentation will depend upon:
- the level of detail required;
- whether time and/or resource is being shown;
- the context of the work (e.g. construction, IT, engineering or business change);
- the dimension being scheduled (project, programme or portfolio);
- the target audience.
The most common form of graphical schedule is the Gantt chart. In its simplest form this uses bars on a horizontal timescale to show the start, duration and finish of packages of work. Variants of the Gantt chart can convey all manner of information to suit the circumstances.
A communication management plan is used to explain who is to receive scheduling information and when. The choice of presentation is tailored to the recipients.
Schedules are contained within the P3 management plan. The schedules that form part of the approval of the work become the baseline against which progress is tracked.
Schedules are fundamental to the control of the project, programme or portfolio. Care must be taken in selecting modelling and calculation techniques, forms of presentation and software tools. Scheduling policies will be set out in the P3 management plan so that scheduling is consistent and widely understood.
On conclusion of the work, schedules that show what was planned and what actually happened are an important resource in determining lessons learned.
Outputs are produced at project level and this is where the most detailed scheduling can take place. The approach to scheduling will depend upon the nature of the project in relation to the triple constraints of time, cost and scope.
Some projects may have to be delivered by a specific date, others within a limited budget, or using limited resources. Some projects may have a very well-defined scope of work and others may intend to develop the scope iteratively throughout the life cycle (often known as Agile project management).
Where there is a well-defined scope of work it will often be presented as a work breakdown structure (WBS) showing how major packages of work are progressively broken down into individual activities.
Schedule management runs in parallel with other processes such as scope management, risk management and quality management. In the early parts of the project life cycle the amount of detailed information available is limited. A schedule may be restricted to indicating target dates for major milestones. As these cannot be calculated from a detailed description of work, the milestone dates may initially be estimated using comparative or parametric forms of estimating.
Once scope management has identified the work required, a detailed model can be built showing how the work will be performed. Various methods can be used on the model to calculate the start and finish dates of all the component activities. Some of these methods only consider the estimated time required to perform each piece of work, while others will allow resources and productivity rates to be included.
Traditionally, the schedule concentrates on the technical activity of delivering the project’s output. It is becoming increasingly common to include management activity in the schedule, such as communications activity, quality control activity or risk response activity. In some cases these are combined into a complete schedule and sometimes there are separate schedules, although there must be a mechanism for monitoring dependencies between schedules.
A programme schedule should not be simply an accumulation of detail from the component project schedules. Within a programme there will be:
- projects that are under way and have their own detailed schedules;
- projects that are in the early stages of definition;
- projects that are yet to be initiated;
- programme management activity;
- change management activity in relation to outputs that have been delivered;
- change management activity in relation to outputs being developed.
This variety of types and detail of activity must be collected into an effective and manageable programme schedule.
First of all, the programme must define a consistent approach to scheduling that will be used across the programme. This includes consistent techniques for estimating and calculating schedules, consistent software tools and a consistent approach to summarising information for inclusion in the programme schedule.
Ideally, the programme schedule will include milestones from the project schedules and the change management activity. In particular it must include interdependencies between different projects and other work.
The programme schedule not only provides estimates of the timing and resource usage of the programme, it must also enable decisions to be made about the acceleration and deceleration of work within the programme. Individual projects will be focused on their designated targets. Sometimes, a programme management team will need to divert resources from one project to another in the overall interests of the programme.
A portfolio schedule must encompass a very wide range of work with greatly varying degrees of detail and accuracy. Portfolio schedules must always be communicated in a way that enables stakeholders to understand what information is derived from detailed schedules and what is more speculative.
An important function of the portfolio management team is a version of capacity planning. Portfolio management must ensure that the necessary resources can be procured to deliver the portfolio. It must also avoid bottlenecks and conflicting demands on limited resources. This means estimating the number of resources required and the timing of their utilisation.
The balancing phase of the portfolio life cycle must constantly review changing resource demands and prioritise the allocation of limited resources. Doing this effectively will depend upon the schedule information aggregated from the component projects and programmes.
Ideally, the portfolio support function will provide scheduling expertise to all the component projects and programmes and ensure that aggregated information is consistent and accurate.