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Technical documentation

Lesson 1:

Why is project documentation so important?

In the field of technology, a multitude of different projects are carried out:

  • Energy projects: like the construction of a hydroelectric plant.
  • Construction projects: for example, the construction of an airport.
  • Environmental projects: the reforestation of a forest, waste recycling systems…
  • Industrial projects: manufacturing of a vehicle.
  • Computer projects: designing a web page or an app.

Every technological project arises from the need to solve a problem, and that is why each project has its own characteristics that make it different from the rest. For example, when it is decided to build a bridge to improve communication between two areas, the engineers in charge of the project must analyze that the land where it is going to be built, the dimensions it must have, how much traffic will it bear, what are the best materials to be used… to come up with a solution that suits that particular situation.

It is not the same to build a bridge to communicate two populations that are separated by a very deep valley (Millau Viaduct, in France, image on the left), than to build a bridge that connects two territories that are separated by a sea (Oresund Bridge, between Denmark and Sweden, right image). In the first case, huge height that the bridge must reach may be one of the greatest challenges, while in the second other problems will arise such as the need to fix the pillars on the seabed.

However, despite the fact that each project is unique, there are certain aspects that must be considered in all technological projects. In all cases, previous planning must be done to determine if the project can be carried out or, on the contrary, another solution must be found. This planning is gathered in what is called the project documentation, which is the set of documents that explain how the project is going to be carried out. The project documentation must contain, at least:

  • A description of the project.
  • A schedule (time planning).
  • The project plans.
  • A budget (economic planning).

Description of the project.

The project documentation must contain a general description of the project that includes the following points:

  • What problem is going to be solved.
  • The alternatives that have been considered.
  • What option has been chosen and the reasons why it has been chosen

To help us determine which solution is the most appropriate from a set of several ideas, a very useful tool is the decision matrix. A decision matrix is ​​a table that allows you to rate each of the possible solutions of a project based on several criteria. Depending on the type of project, the criteria will be different, but below is an example that could be used, for the design of a typical object:

As you can see, a rating from 1 to 5 (another range of values ​​can be chosen) has been assigned to each of the criteria and then the average score has been calculated for each of the solutions. For example, the score for Solution 1 has been obtained as:

\large \dfrac{4+5+2+2+1}{5} = \bf{2,8}

In this case, the best solution and the one that, therefore, should be carried out is number 3, since it is the one with the best score.

A slightly more advanced version of the decision matrix consists in assigning a percentage of importance (also called weight) to each of the criteria that are going to be considered. This is useful when you want to give more importance to some aspects than others. For example, in one case we could consider that the aesthetic factor is very important while in another the utility factor may be the most relevant.

¡IMPORTANT! The sum of all the weights must be equal to 1, if they are represented as decimal fractions, or 100 if represented as percentages.

The table below contains the same ratings as the table above, but weights have been added to represent the importance of each of the criteria. In this case, the criteria ordered from highest to lowest importance are:

  1. Profitability.
  2. Utility.
  3. Durability.
  4. Appearance.
  5. Innovation.

In this case, the rating of each idea is not calculated with a simple average, but with a weighted average. For example, the score of Solution 1 considering the weights assigned to each criterion would be calculated as:

\large 0,25 \cdot 4 + 0,2 \cdot 5 + 0,3 \cdot 2 + 0,1 \cdot 2 + 0,15 \cdot 1 = \bf{2,95}

As you can see, the winning idea is now Solution 2. The reason is that this solution has a very good rating in the durability and profitability criteria, that together represent 50% of the total score. Solution 3, however, has very good marks for innovation and aesthetics, but since these are the criteria to which less importance has been given (they only account for 25% of the final score), its score is not as good as it was in the previous example.


The goal of the time planning in a project is to estimate how long it will take to finish it and how long each of its phases will last. The latter is essential, since a project usually involves many professionals from different branches who must be properly coordinated. Imagine that during the renovation of a house the furniture is placed before the painter paints the walls, it would be ridiculous, isn’t it? In any project there are certain jobs that cannot be done until others have been finished and this is just what is intended to guarantee with time planning.

One of the most used tools when scheduling a project is the Gantt chart. In a Gantt chart, each activity or project phase is represented by horizontal bars whose length is related to the duration of the activity. These bars indicate when each of the activities should start and end. This way, it is it is possible to calculate the total duration of the project, which is not easy in very complex projects with a large number of activities.

Below you can see the Gantt chart of the construction of a residential building:

As you can see, it is usual to gather activities into groups. In this case, the groups are: pre-design, design, supply of materials, construction and delivery to the customer. Each of these phases consists of several activities whose added duration must be equal to that of its phase.

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