General
A schedule is a timetable showing the work involved in a project, programme or portfolio. It is a dynamic document that is created and maintained throughout the life cycle. Schedules can be created for different aspects of the work and these are an important means of communication with all team members and stakeholders.
To be realistic, schedules must reflect the impact of resource availability, risk and estimating accuracy on the performance of the work. The goals of schedule management are therefore to:
- determine timescales for the work;
- calculate profiles of resource demand;
- present schedule reports in a format suitable for different stakeholders.
The schedule management procedure will vary in accordance with the context of the work but a typical high level procedure will follow the steps below:
The planning step will define the techniques and approaches that will be used to identify, schedule and report. The initiation step will ensure the necessary resources are acquired and mobilised.
The same top down and bottom up principles are also applicable to large projects that may be divided into sub-projects.
Scheduling starts with the identification and definition of the work that is needed to deliver the objectives. Some work definition may have been performed as part of the scope management procedure but that is now developed in more detail.
This identification will be performed both top down and bottom up. Within a portfolio or programme, the work will be identified in large components, i.e. the projects and programmes within a portfolio or the projects within a programme. This may identify top level constraints that are passed down to the component programmes and projects.
Detailed scheduling based on analytical models is then conducted at project level with the results feeding back up to the high level programme or portfolio level.
Schedule reports range from simple milestone charts to the statistical complexity of Monte Carlo distributions. Which reports to use for different stakeholders can be set out in a schedule management plan or a stakeholder management plan if preferred.
Schedule management is concerned with the time aspect of the triple constraint. It is therefore closely inter-related to the functions that deal with the other two aspects, namely, scope management and financial management (cost).
In some contexts (e.g. traditional construction and engineering) scope is defined first and the time and cost is derived from this. In others, time and/or cost may be the principle constraints with scope being dependent upon the time and cost available. This is known as an agile approach.
The approach to developing schedules has to reflect this relationship between time, cost and scope. In some cases, rigorous techniques can be used to model the work and calculate detailed timings. In other cases, initial broad estimates are made that are constantly refined as more information becomes available.
The more detailed models described in time scheduling and resource scheduling can be used to test different scenarios. During the definition process these may relate to alternative solutions, with the aim of understanding the schedule consequences of achieving the objectives in different ways. During the delivery process different scenarios might test alternative ways of creating an output or responding to a risk event occurring. Testing theoretical scenarios in this way is commonly called ‘what-if?’ scheduling.
The factors affecting the way in which schedules are presented typically include:
- the level of scheduling detail required;
- whether schedule information needs to be combined with resource and/or scope information;
- the context of the work;
- the audience for the information.
By far the most common way of presenting schedule information is a form of bar chart known as a Gantt chart. This can simply show the performance of activities on a horizontal timescale or it can be combined with logical dependencies between activities, resource usage or progress information.
Praxis makes the distinction between delivery plans and management plans. The former is about the timing of what will be done while the latter is how the work will be governed.
While a schedule is primarily about timing, the combination of time and other information is more commonly referred to as a plan.
Delivery plans are fundamental to control techniques so care must be taken in selecting the modelling and calculation techniques that are most appropriate to the context of the work. There are numerous software tools that enable work to be scheduled and presented in different ways. How scheduling should be performed and which tools should be used will be set out in a schedule management plan if the complexity of the work justifies it.
Projects, programmes and portfolios
Most detailed scheduling takes place at project level where the outputs are produced. Traditionally, project schedules concentrated on the technical activity that creates products but more recently, management activity is also being included. As the complexity of the work increases it becomes impractical to maintain a single detailed schedule.
Large scale projects will often use rolling wave planning where only short term work is shown in detail with longer term work being shown in summary. As the amount of management activity increases it may be useful to create separate delivery plans for different areas such as a communications plan or a benefits realisation plan.
The need for multiple plans is inevitable as complexity increases. Within a programme for example, there will be diverse components such as:
- projects in progress that have their own detailed delivery plans;
- projects that are not yet initiated;
- management activity (e.g. communications, procurement etc.)
- change management activity.
At programme level there should be a delivery plan that summarises the component plans. For this to be effective, the management team must ensure that similar scheduling policies are adopted across the programme. These policies may be set out in a schedule management plan.
In order to avoid the top level programme plan becoming cumbersome it will contain summary ‘activities’ that may represent entire tranches or projects. Other information may be represented as key milestones extracted from more detailed plans.
The greatest diversity of planning information exists in a portfolio. Portfolio plans need to be presented in a way that enables stakeholders to understand what information is derived from detailed schedules and what is more speculative.
An important aspect of the portfolio management is capacity planning. This ensures 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. Schedules must be consistent in the way they estimate activities and allocate resources so that aggregation at the portfolio level is accurate.
The portfolio management process must continuously balance 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.
