Understand Resource Constrained Schedules

Developing a schedule is not trivial and requires advanced methods, tools and techniques to solve complex scheduling problems. 10 min read.


Organisations capable of delivering projects by their due date improve owner/customer goodwill. If this can be achieved through the efficient use of organisation resources, then the organisation is expected to have a competitive advantage in the marketplace.

Determination of a schedule to complete projects exactly on their assigned due date is considered a primary objective for many organisations. In some situations,

  1. Projects completed before their due date are not handed over to the project owner/customer but held within the organisation that executed the plan resulting in unnecessary front-end costs while waiting for back-end payment.
  2. While projects completed after their due date are considered tardy and result in a loss of goodwill and penalty.

The objective in such situations is to meet the due date of the particular project as closely as possible and consequently minimise project earliness and tardiness because they greatly influence the performance of a schedule with respect to cost.


Project management is increasingly vital in today’s competitive environment and receives a growing amount of attention both in production and in services sectors. Organisations more and more are adhering to project-based organisations and work, for a wide range of applications.

Projects face delays in project completion due to improper planning. The high degree of complexity, tight completion, and scarcity of resources involved in real-life projects necessitate the application of modern project management methods, tools and techniques for the satisfactory achievement of objectives and smooth project execution.

Present-day projects are constrained by resource availability because timely allocation of resources is necessary to avoid activity waiting time or delays. Moreover, resource management is an essential organisation factor to remain competitive and profitable. Therefore, to control costs, labour, equipment and tools should be utilised efficiently.

Resource-Constrained Project Scheduling Problem (RCPSP)

Resource scheduling problems arise when there are definite limits on the availability of resources, and therefore the objective is to meet the project due date as closely as possible, subject to the fixed restrictions on resource availability.

For an individual project, sequencing rules are used to determine which one of the competing activities will have priority for resource allocation. In priority-scheduling,

  1. When an activity requires a resource and if the resource is free, then the resource is allocated to the activity, otherwise, the activity is placed in the resource queue.
  2. As soon as the resource becomes free, an activity from its queue is chosen according to its priority rule, and the resource is allocated to the chosen activity.

Unfortunately, no universally acceptable scheduling rule exists that satisfies a project objective. Therefore, several rules need to be assessed to find the optimal solution. Similarly, if a project changes its objective then different rules need to be considered. This is because of the unique underlying project characteristics and resource usage. Unfortunately, off-the-shelf project tools use only one priority rule meaning results are less than optimal.

Resource-Constrained Multi-Project Scheduling Problem (RCMPS)

Multi-project scheduling is significantly different from single project scheduling. The variation in the properties of resources, activities, projects and the solution algorithms add to the complexity of this problem.

The necessity of managing multiple projects mostly of different nature, within one-time frame, in a resource-constrained environment makes the problem a significant organisational challenge. In real life, there exists a necessary dependency on activities for the use of the same resources. As a result, the problem of multi versus single resource-constrained scheduling becomes more difficult.

Moreover, another problem with multi-projects is that individual projects may have separate goals and challenges, and yet draw at least some of the same resources from a shared pool. Consequently, frequent conflicts of interest occur when more than one project requires the same resource at the same time.

Similar to single schedules, no universally acceptable scheduling rule exists that satisfies a multi-project objective again because of the unique underlying project characteristics and resource usage.


Project scheduling is made more challenging when limited resources are considered. Not only does the underlying project characteristics need to be considered but also the temporal aspects of resource allocation and availability, which is made more difficult again in a multi-project environment reliant on a shared resource pool.

While simple projects can be solved by hand, as project complexity increases, sophisticated project management methods, tools and techniques are needed to solve resource-constrained project scheduling problems.

Using Oritames artificial intelligent assisted autonomous machine learning capability can result in 30%+ improvements when compared to off-the-shelf project management tools.

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Learn More

If you would like to know more about leveraging data-driven actionable insights to solve your complex project scheduling problem, then feel free to contact me on itierney@pminsight.com.au.

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