**3. The simulation of the construction of a bridge**

along the deck (**Figure 5**). The interface presents diagrams linked to dimensional parameters, in order to facilitate the description of the geometry established for each concrete case of the deck. The 3D model is the result of an appropriate combination of two longitudinal geometric components: the deck morphological evolution and the layout of the road, which acts simul‐ taneously over a cross section, defining the exact deck shape'. The Annex item includes the algorithms used to calculate the 2D coordinates of each vertices of this type of cross section.

The geometric database, needed to create the 3D model of the deck, is formed by a set of geometric parameters, which the bridge designer deals with at the conceptual design stage. To obtain the 3D model of a deck segment, consecutive sections corresponding to the con‐ struction joints are generated using the algorithms of the program and connected to surfaces. The final configuration of the deck is comprised of two longitudinal surfaces: one representing the exterior side of the deck and the other its interior. The top cross sections are finally added to the 3D model (**Figure 5**). As this model uses cross sections correctly defined in shape and in their spatial orientation, it represents the real form of the deck. After the deck, 3D model is completed with the pillars and abutments, and it is inserted into the landscape. The aesthetic

evaluation can then be carried out.

62 Structural Bridge Engineering

**Figure 5.** Box girder cross‐sectional interface and 3D model.

**Figure 6.** Longitudinal section and cross sections with different shape and transversal slope.

Technologies supporting 3D modelling and interaction with the models, which add to a better understanding in the teaching‐learning in the classroom, have been introduced into schools [6, 7]. In particular, information and communication technology applications in higher education have been reported as improving learning, especially in course – based team learning and collaborative learning [8, 9]. In the field of education and training virtual reality (VR) technology has been used as a leading way for a better understanding of didactic issues, performed in face‐to‐face classes or in e‐learning platforms. VR technology has proved very useful in the teaching of incremental processes [10]. The models that allow the visualization of the construction process of a building or bridge are 4D models, that is, they use the time factor linked to 3D construction components.

When implementing a 4D application, the designer must have a clear idea of what to show, because the objects to be displayed and the details of each one must be appropriate to the goal that the teacher wants to achieve with each specific model. In the development of the 4D bridge models, VR techniques were used, in order to improve their efficiency by allowing the interactivity by all parties involved in each type of bridge construction [11].

The 4D applications that were developed concern some of the most widely applied method‐ ologies in bridge deck construction [12]. The 4D models allow users to demonstrate a process and present, briefly, the fundamental theory of the process or provide full information concerning the experiments. In the field of civil engineering, there are several construction methods for the building of bridges. The most frequent constructive processes for bridge decks are (**Figure 7**): bridge deck formed by precast beams [13]; cantilever construction [12] and the incremental launching method [14].

**Figure 7.** Methodologies of deck bridge construction.

In order to establish the principal characteristics of each construction method, to define the type and quantity of the construction components needed to be modelled for the simulation of each construction work and, also, to perform the correct sequence of operations, the bibliographies concerning the three methodologies of bridge construction were consulted [12–14]. Based on this information, the 3D model of each type of bridge was generated and the corresponding sequence animation of each construction process was programmed. Because specialists in construction processes and bridge design were consulted in the implementation of these 4D models, the final product is efficient and accurate. Through direct interaction with the models, the progress of the actual construction process of the bridges can be monitored.
