My MBA Journey

Record of my personal journey completing an MBA

Project Management Week 4 – Project Scheduling and Project Duration

Project scheduling


This week covers the scheduling of the costs and resources for a project. When this is completed, the project can commence. As a project manager, you are also a resource and need to be conscious of the time spent on managing projects to ensure your time is spent wisely.

Resource Scheduling and Allocation Methods

Resource Scheduling Problems

Once resources are allocated to a project, it is then possible to see the impact that these have on the time and cost factors. Non critical tasks do not require excessive resources applied to have them completed quickly. As a result, resources can be spread more evenly over the period of the project.

Alternately, if there are inadequate resources at times of peak demand, then these tasks may need to be started later. The process is referred to as resource-constrained scheduling. Not scheduling resources correctly can be very costly to a project and if identified, then immediate action is necessary to mitigate any cost increases.

A noticeable aspect of resource scheduling is where multiple tasks need to be completed by the same resource. Obviously, this puts considerable pressure on the resource if too much is demanded at any given time. For this reason, the tasks need to be scheduled to take account of these issues. This concept is demonstrated in the following diagram.

Figure 1: Constraint Examples

Contraint Examples
Source: Larsen and Gray (2020)

Time and resource constraints can place considerable impact and strain on projects. The allocation of resources can be an evolving situation as the interactions between tasks become visible. Computer software can assist considerably with this modelling and allow for rapid adjustments where necessary that will flow through to the entire project.

Resources provide the ability to drive the project and at the same time can constrain its progress. Finding the balance is the role of the project manager. The constraints placed upon projects usually comes in one of three forms being people, materials and equipment.

When it comes down to scheduling problems, there are two that are particularly identified in the text (Larsen & Gray, 2020). A time constrained project must be completed by a particular date. Because of the date, additional resources may need to be found and allocated to meet the deadline. The second problem can be one of a resource constrained project where the resources are effectively fixed and cannot be varied. In such a case, the time may need to be extended.

Resource Allocation Methods

When it comes to resource allocation, the text suggests assuming that all the scheduled tasks are completed within the scheduled time frame. In reality, on large projects, this simply would not happen. It may be the case for smaller projects where control of the resources can be greater.

Resource scheduling is nothing more than the allocation of tasks over a time period. This is normally done using Gantt charts. These use any slack to move the start time around if necessary.

Time Constrained Tasks

Resource allocation is the key when scheduling them on time constrained projects. Demand for a resource that is erratic is hard to predict and also manage and result in poor deployment practices. Project managers normally would use what are known as “levelling techniques” and use any slack in a task to manage the time allocation. If tasks are not critical, this is not an issue because the non critical task can be shifted to another time. If a task is critical, it no longer becomes a time constrained issue but an issue that threatens the success of the project.

Resource Constrained Tasks

With a resource constrained task, where either people or equipment are not available when required, the project manager will need to reschedule in order to prioritise the task with the equipment available at that time. This can be a challenge. Although mathematical solutions have been developed for such challenge, they may be suitable for smaller projects, but not for larger ones. Larson and Gray (2020)[1]refer to work that has been done regarding these methods (Davis & Patterson, 1975; Fendly, 1968 as cited in Larson & Gray, 2020).

The parallel method seems to be the most commonly used one for the allocation of resources over tasks to minimise any delays in a project. It applies priorities to the tasks or activities based on rules of:

  1. Minimum slack
  2. Smallest duration
  3. Lowest activity identification number

Tasks that can’t be scheduled without delaying other tasks are moved out further on the time scale. This would not apply of course to activities that have already commenced. When activities require the same resources and delays need to be addressed, then the priority rules will apply. For example, if a project has four activities that are ready to commence and all require the same resource, the one with the least amount of slack will be the first to start.

The following video was recommended in the notes regarding Critical Path Management (CPM) and Critical Chain Path Management (CCPM). It explains the differences between the two and the benefits of each method in particular circumstances. Although the explanations are fine, it is from a software company promoting their wares.

Differences Between CCPM and CPM in Project Management

Using Resource Schedules to Develop Project Cost Baseline

When it comes to large projects there are often hundreds of activities on the go at the same time using all manner of costs and resources. This is where a project manager needs to be aware of how the project is travelling over particular time frames and a time phased budget should be developed. When a project is budgeted over a period of time at considerable cost, it is pointless waiting until the end to see if the project has met budget. For example, if a project is estimated to cost $400,000 and the time to be taken is 12 months, the project manager needs to know on an ongoing basis the costs that have been incurred. It is also important here that the expenditure on the project is allocated against the activities on an individual basis to keep track of such expenses. The total expenditure is not necessarily an indication if some activities have not started and others have gone over budget. As a result, it is important to know when costs will be incurred over the project timeframe.

Critical Chain Approach

The critical chain approach to project management comes from the theory of constraints developed by Goldratt (1984.). The theory is predicated on there always being one activity, which is usually a bottleneck, being critical to the project result. The entire project success is dependent on that activity and its result.

The critical path, a key definition, is the longest amount of time that is taken through the project network. The critical chain approach however also takes resources into account. An example is that where a task involves the use of people and equipment, there is a reliance on both resources being in good order to complete the task. There is a synergistic relationship between the two.

Reduction in Project Duration

Time management in a project is obviously important and reducing the amount of time involved can have impact on costs and resource usage. The shorter the time a project takes to complete, the better, with the obvious qualification around quality needed. One of the first places to look at activities that can reduce project duration is the critical path of the project. Any reduction to any of the tasks here will immediately reduce the amount of time for the whole project. The only caution here is to be aware if the reduction in a critical task possibly has an impact on the critical path itself.

Justifying a Reduction in Project Duration

Many reasons may be given as to why a project needs to be completed in less time. The industry refers to shortening the length of project as crashing. One issue here is that this may be done for reasons of politicisation so that projects can be called a success and delivered within time and below budget. In reality though, there may be issues arising from the project that flow into the future and require additional resources and costs that are not allocated against the project. There may also be situations where project incentives are exploited as well for early completion.

Any suggestions around “crashing” projects should be reviewed to ensure all the detail has been presented and the suggestion is viable.

Options to Accelerate a Project

There are a number of methods that can be used to accelerate a project. Where resources are not constrained in terms of cost, the project manager can employ more people, hire more machinery or the like. Another example is known as “doing the project twice” where the project is completed in two parts. Part one will complete the project within a deadline allowing for launch, but people may still be working on non-critical aspects of the project for a period of time afterwards. This doesn’t affect the launch of the project.

When resources are constrained, this adds an entirely new dimension to to the situation. Some parts of a project may be removed or quality reduced in some areas. For example, if a house bathroom was to have gold plated taps which would take 2 months to import, they could be replaced with chrome ones immediately.

The text also refers to methods such as fast tracking, critical chain, reduction of scope and compromises in quality as additional methods. Fast tracking rearranges resources for more effective utilisation, such as laddering. Scope reduction can also accelerate a project if it hasn’t started. Agile project management is another method suggested for the acceleration of projects.

Cost Duration Graphs

It has already been mentioned that the best way of reducing the project time is to reduce the time taken for activities in the project that lie on the critical path. The choice of activities will be contingent on the cost involved. This is not only the direct cost, but the indirect costs as well. To complete a cost duration graph you need to identify the tasks that can be shortened at the least amount of cost and then recalculate the total cost of the project.

Figure 2 – Project Cost Duration Graph

Project Cost Duration Graph
Source: Larson and Gray (2020)

Practical Aspects of Reducing Project Duration

The notes suggest that a cost duration graph is quite sophisticated for the majority of projects but can be useful in larger projects. Furthermore, the suggestion is made that not too many project estimators have experience with the process and also that there is associated risk in crashing a project. Another consideration is that a cost duration graph assumes a linear basis for the direct costs and this is rarely the reality. Costs can vary considerably over time frames.


The scheduling costs and resources is a critical component of project management. Project managers should ensure that resources are allocated efficiently. Resource scheduling problems can be costly to a project and immediate action is necessary to mitigate any cost increases. Gantt charts and levelling techniques are two methods that can assist in managing any time or resource constraints.

The parallel method is commonly used for allocating resources across tasks so that project delays are minimised. Resource schedules should be developed by project managers to establish a project cost baseline. This can also be used to see how the project costs are progressing over time. Computer software can also be used to help in modelling and assist in making adjustments where necessary. The project manager needs to find the right balance between resources and constraints so the project is properly managed.

  1. Larson, EW & Gray, CF 2020, Project management: The managerial process, 8th edn, McGraw-Hill, New York.[]

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Ric Raftis

Ric Raftis

Find out more about me on my About Me page.

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