Image: Municipality of Arouca

Brave new lengths

516 Arouca, Portugal

Located next to the Paiva Walkways, the world’s longest pedestrian suspension bridge, 516 Arouca, was built in order to consolidate the active tourism project in the Paiva valley, facilitating access to the Eastern area of the municipality of Arouca. The bridge is located in an area in the heart of Arouca UNESCO Global Geopark. The structure provides a fascinating view of two of the 41 geosites that make up the geopark: Aguieiras Waterfall and the Paiva Gorge.

The initiative to connect the two banks of the Paiva River arose in 2016 with the intention of the Municipality of Arouca to allow the crossing between Alvarenga and Canelas, thus complementing the network of walkways and at the same time enabling an elevated view of the waterfall. The Institute for Research and Technological Development for Construction, Energy, Environment and Sustainability (Itecons) was challenged to create this link, and its team was responsible for the concept, analysis and design of the bridge. The local topography, the difficulty of access and the geological conditions forced a change to the initial plans, which led to the creation of a bridge with a span between pillars of 516.5 m and approximately 175 m above the river.
Arouca Portugal

Over several months, rigorous calculations were made on the action of wind speeds on the bridge; cable resistance was extensively tested using numerical models and prototypes tested in wind tunnels. Various construction and anchoring solutions have also been meticulously studied. Using a significant series of innovative techniques, all the numerical and laboratory work sought to find the ideal structure, ensuring safety for the crossing to the smallest of details and at the same time guaranteeing adequate levels of comfort.

In the design of the suspension bridge project, the design team opted for a profile with a concave shape (formed by a set of various decks) because it allowed a reduction of the load effects and anchorages of the structure. The bridge has been designed in order to guarantee that even in the unlikely event that one of the cables break, the decks will remain connected, maintaining the bridge’s safety.
The next step was to create towers that allowed the elevation of the level and the angle of the main cables (catenary) to be raised, which suspend the decks by means of hangers.

Arouca Portugal

The equilibrium of the towers is achieved through the continuity of the catenaries to the opposite sides of the central span, in the direction of the anchorage blocks. Before proceeding to construction of the project, it was necessary to find solutions for the horizontal forces, generated in particular by wind loading. Due to the natural difficulties of executing this project, Itecons adopted a solution that consists of tilting the planes on which the catenaries and hangers work, creating vertical and horizontal components that promote the balance of the entire structure. Angles of about 20º in relation to the vertical were adopted.

516 Arouca is made up of 127 galvanized modules with galvanized decking panels, each functioning as a kind of independent cell, which strengthens the feeling of safety and comfort for visitors. In order to maximise the crossing experience, it has been stipulated that a limited number of people can be simultaneously on the bridge. It is intended that each visitor can enjoy the crossing in all its splendour, being able to observe the landscape, without an excess of tourists interfering with this idyllic setting.

1 | 516 Arouca is made up of 127 galvanized modules with galvanized decking panels, each functioning as a kind of independent cell

2 | Galvanized steel will ensure the protection of the bridge steelwork for many years

3 | The world’s longest pedestrian suspension bridge, 516 Arouca, was built in order to consolidate a UNESCO site

Designers | Itecons

Photos © Municipality of Arouca

Image: Municipality of Arouca

Posted on December 21, 2021 by Galvanizers Association

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