Triple constraints or the iron triangle
Each project plan specifies its duration, costs and availability of resources (in terms of people, equipment, etc. necessary to achieve the project's objective) while maintaining required quality. The iron triangle, the golden triangle or the triangle of the triple constraints, is a graphical presentation of the aspects of the project: time, scope and budget. In each project they must be balanced correctly so that the project runs properly.
The scope of work (functional specification) is a document defining the project boundaries. The scope of the project is the basis for defining the project tasks and workload and defines exactly what is to be done. It is a set of activities that are necessary to achieve the main goal.
The cost expressed is specified in the project's budget. The budget is defined for the project as a whole, but also for its main stages. When the client clearly defines the upper limit of the budget, the scope of the project is adjusted so that this limit is not exceeded.
Usually the client decides the timeframe of the project. The duration of the project is also related to the budget, it can be reduced, but it usually requires additional assets. Project managers strive for the most efficient use of the time allocated to the project, all the time keeping in mind the achievement of the goal, to complete the work within a given period.
Quality, the fourth parameter
It is important to take into account the constraints, since one parameter can not be changed without changing the others, due to their interaction. There is also fourth parameter of the triangle, quality, which is a component of each of the individual parameters. For example, if we completed the tasks faster than we planned, we can extend the scope of the project or spend more time on individual tasks, which in turn will give us a better quality product.
Optimization and balance
There are several ways to optimise the individual parameters of the triangle, and a good project manager must always ensure that they are in balance with each other. The scope can be optimised by allocating additional resources to ensure the implementation of all tasks, or by an extension of the project implementation date. Budget can be optimised by reducing the amount of resources needed, as well as its adequate allocation. Timing can be optimised by implementation of project tasks or reducing the scope. The constrains, however, are always interlinked, therefore a change in one of them automatically triggers changes in another. Optimization of triple constraints shall take place in the planning phase, the most important of all, and project manager shall be monitoring the execution and follow closely. Therefore, the most important aspect in order to make sure the project runs smoothly is its constant control.