## 4 Discussion--Challenges and Opportunities for the Bridges of Peru
### Challenges in New Digital Technology Tools to Support Bridge Construction
Thus, the piles were located outside the width of the river's water surface in order to carry out the construction work during the dry season of the Nanay River (May-October). The piles were built with benthic mud support and materialized with reinforced concrete. On the other hand, after the piles were built, the construction of the pylons considered the following phases: (i) construction of the deep foundations, (ii) construction of columns below the level of the lower crossbeam, (iii) construction of the lower crossbeam, (iv) construction of the column base above the level of the lower crossbeam, (v) construction of columns above the level of the lower crossbeam, (vi) construction of the upper crossbeam, and (vii) construction of columns above the level of the upper crossbeam. The bridge deck was then built using successive 10 m segmental cantilevers. The segments are composite sections, with plate girder steel beams and concrete slabs joined by shear connectors. The elements of the metal structure were manufactured in the city of Lima, where they were then transported to the project area. The concrete slabs were prefabricated in the civil works area, and after assembly, they were joined by concrete strips built on-site. This is how the segment assembly used mobile lifting systems (see Figure 16). Figure 16: BIM of Nanay bridge. Adapted from [29]. In the above, the sequence of assembly of the segments was as follows: (i) The elements of the metal structure that are in the river raft were lifted by means of cables by the mobile lifting systems up to the level of the bridge deck work area. (ii) The metal elements were assembled by joining the lifted elements to the previous segment by means of connection bolts by the assembly operators. (iii) Once the assembly of the metal segment was finished, the metal segment was connected to the respective stay or cable, which was anchored in the pylon. (iv) The prefabricated slab panels were then lifted from the raft, and the concrete panels were placed on the template of the metal segment already assembled and supported by the stay cables of the bridge. (v) Four mobile lifting systems were used, two for each pylon, and each system was provided at its front with two hydraulic lifting jacks. (vi) The union between concrete panels was made by means of concrete strips that were placed on-site, where the stay cables were then tensioned, inducing significant pre-compression in the concrete slab. The construction process described above was supported by two high-lift cranes located on the side of each of the bridge pylons (see Figure 17). Finally, the aerodynamic stability of the bridge was analyzed. In this sense, at the location of the Nanay bridge, the Peruvian Design Code establishes a design wind speed of 95 km/h at 10 m above the ground for a return period of 50 years. Despite the use of a torsional weak open section, the use of an H-pylon configuration with two planes of cables allowed the bridge to achieve a ratio that is within the limits to prevent flutter instability. Wind tunnel testing was conducted to further ensure the stability of the bridge during construction and operation. A second example corresponds to the La Joya Virgen de Chapi Bridge Project, where the bridge is of a structural steel arch type, where the BIM (Building Information Modeling) methodology was implemented together with the DfMA (Design for Manufacturing and Assembly) concept with the following purposes: (i) carry out the collaborative work of the different project actors, (ii) reduce errors, deviations, and uncertainties as much as possible in the engineering, construction, and project management stages, and (iii) control the risks of the construction process, considering the industrial manufacturing of components (avoiding on-site work if possible), transportation, and assembly of different elements of the bridge infrastructure, among others. Figure 17: Panoramic view of the construction process of the Nanay bridge. Adapted from [29].