During the afternoon and evening of September 3, 2023, and the early hours of September 4, an extreme meteorological phenomenon known as “DANA” occurred, primarily affecting the southwestern area of Madrid. The storm caused severe flash floods that led to the collapse and damage of several structures.

The most serious consequences occurred in Aldea del Fresno, where three access bridges to the municipality collapsed, specifically on the M-507 and M-510 roads.

The new Pedrera bridge replaces one of the bridges that collapsed that day. The previously existing bridge from the 18th century has been preserved as a museum piece of its ruins, and a decision was made to build a new structure according to modern standards.

A 5-span viaduct was chosen for construction, upstream and parallel to the 18th-century bridge, with spans ranging from 30.55 m to 47 m. The total length is 202.1 m, and the width of its deck is 15.2 m.

This structural type selected presents the least possible obstacle to the water, not only due to the distance between the piers but also due to the elevation of the deck several meters higher than the historic structure. Additionally, the rigid cable-stayed solution allows for a lightweight and slender deck, formed by a continuous concrete slab from abutment to abutment, requiring only four intermediate supports.

First, the foundation was executed using pile piers. Then, the abutments and piers were constructed, which were quickly built by extending the piles with straight reinforced concrete shafts.

The deck, manufactured off-site, was transported in sections to the site for assembly. This was necessary to minimize the size of the sections so that the trucks could transport them without issues on the M-510 and M-507 roads.

Since the deck of the new bridge has been elevated by 2 meters compared to the historic one for hydraulic reasons, a solution was needed for the new connections to the access roads. On the west side (right bank), the elevation was adjusted along the next 200 meters to connect with the road. On the east side (left bank), the solution was more complex due to the nearby T-intersection between the M-507 and M-510 roads. Finally, the adopted solution was the construction of a roundabout.