Chapter 1. Introduction to Project Management

1.3 Project Constraints

Projects do not live in a vacuum. They are affected by many factors including constraints, assumptions, and internal and external factors (referred to as Enterprise Environmental Factors – EEFs by PMBOK Guide 6th Edition). Three main constraints (i.e., triple or iron triangle constraints) are scope, schedule, and cost, and they are considered the main pillars of a project. They are also regarded as the main reason why we need a systematic project management approach. These primary constraints also compete with each other. Therefore, project managers should consider trade-offs among them. For example, increasing the project scope may require a revision of the schedule and budget. In many cases, expanding the project scope with more product specifications and project activities would result in a longer schedule and higher budget. This trade-off will be discussed in the following sections, and mostly in their respective chapters. Maintaining the balance among these constraints is difficult because projects are prone to change. Thus, the technical and interpersonal skills of project managers, and how they utilize the best and proven practices of project management, and the quality of a project team are essential prerequisites of conducting an effective project.

Besides triple constraints, the other three constraints which are also tightly linked to the triple constraints are resources, quality, and risks. Tightly aligned with and at the top of all these six constraints, the success of a project depends on the client and/or stakeholder satisfaction. Clients make their decisions to accept the final deliverables of a project by evaluating these constraints.


Project scope is the work performed to deliver a product, service, or result with the specified features and functions[1]. Scope refers to what the project is trying to achieve. It entails all the work involved in delivering the project outcomes and the processes used to produce them. It reflects the purpose of the project. The difference between the project and product scopes will be detailed in Chapter 4 “Project Planning”.

A project is built upon the scope. After all the product or service requirements are elicited from all relevant stakeholders, observations, documents, and other sources, the project manager can start working on the project activities which will be carried out to meet these requirements. After product requirements and project activities are defined, and the activities are sequenced, the project manager and the team can proceed with the estimation of activity durations, allocation of resources, estimation of costs, and identification of risks, quality, and performance metrics.


A schedule is a model for executing the project’s activities, including durations, dependencies, and other planning information[2]. Project scheduling provides a detailed plan that represents how and when the project will carry out all the activities that would lead to the delivery of the products, services, and results defined in the project scope. It serves as a tool for communication and collaboration with all the stakeholders and managing and monitoring their expectations. It also serves as a baseline for performance reporting[3]. While monitoring the performance and progress of a project, a schedule is assessed commonly to identify problems (e.g., delays, missed deadlines, incomplete deliverables) in the project. After the project team defines the activities based on the product and project scopes, activity durations are estimated, activities are sequenced, their interdependences are outlined, and hence, the resources can be allocated to each activity. The project schedule should also consider national, federal, or local holidays and the absence of human resources due to vacations and other issues such as sickness and family issues. We will discuss scheduling in Chapter 7 “Scheduling”.


Cost is the budget approved for the project including all necessary expenses needed to deliver the project. Within organizations, project managers have to balance between not running out of money and not underspending because many projects receive funds or grants that have contract clauses with a “use it or lose it” approach to project funds. Poorly executed budget plans can result in a last-minute rush to spend the allocated funds. For virtually all projects, the cost is ultimately a limiting constraint; few projects can go over budget without eventually requiring corrective action. We will discuss cost management in Chapter 9 “Budget and Procurement”.


Quality is a combination of the standards and criteria to which the project’s products must be delivered for them to perform effectively. As quoted by the PMBOK Guide 6th Edition from ISO 9000 standards, “quality as a delivered performance or result is the degree to which a set of inherent characteristics fulfill requirements”. The product must perform to provide the functionality expected, solve the identified problem, and deliver the benefit and value expected. It must also meet other performance requirements, or service levels, such as availability, reliability, and maintainability, and have acceptable finish and polish. We will discuss quality management in Chapter 11 “Monitoring and Controlling”.


In order to carry out and complete project activities, the project manager should allocate various resources such as human resources for the project team and all other activities, physical resources (e.g., equipment, materials, facilities, software, testing environments, licenses, infrastructure, and supplies), and services (e.g., consulting and subcontractors). Resources can be determined and allocated when the activities are defined and scheduled. Then, the budget for each activity can be computed based on the allocation of all resources. We will discuss resource management in Chapter 8 “Resource Management”.


A risk is an uncertain event or condition that, if occurs, has a positive or negative effect on one or more project objectives. Negative risks are called threats, and positive risks are called opportunities[4]. Two main factors determine the severity of a risk: (1) Probability of the occurrence, and (2) impact on the project. Risk responses are planned based on the severity level. We will discuss individual and overall project risks and their management in Chapter 10 “Project Risks”.

  1. Project Management Institute. (2017). A guide to the Project Management Body of Knowledge (PMBOK guide) (6th ed.). Project Management Institute.
  2. Project Management Institute. (2021). A guide to the Project Management Body of Knowledge (PMBOK guide) (7th ed.). Project Management Institute.
  3. Project Management Institute. (2017). A guide to the Project Management Body of Knowledge (PMBOK guide) (6th ed.). Project Management Institute.
  4. Project Management Institute. (2021). A guide to the Project Management Body of Knowledge (PMBOK guide) (7th ed.). Project Management Institute.


Icon for the Creative Commons Attribution-NonCommercial 4.0 International License

Project Management by Abdullah Oguz is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

Share This Book