Nestled in the heart of Rioja, Spain, lies a new pedestrian footbridge which seamlessly links the historical center of Haro and its surrounding wineries. Inspired by the town’s vibrant wine culture, the design features Outokumpu’s stainless steel which boasts a striking appearance and longevity.
Haro is a major hub that flaunts wine bars, bodegas, and vineyards renowned for their locally produced and world-famous Rioja wine, drawing visitors from across the globe. The town’s wineries are in the Station Quarter, near the historical center of Haro. But two major barriers limited access to the town: a national road and the Tirón river. To resolve this, Haro City Council has constructed a footbridge which gives safe passage for tourists from the wineries directly to the town. It turned to structural engineering consultancy Arenas & Asociados to design a visually appealing, sustainable bridge that adapts to the soft topography of the riverbanks and pays homage to the bustling wine culture of the region.
Arenas & Asociados used stainless steel for the main structure, wood composite for the decking, and stainless steel mesh for the railing. This mirrors the use of materials related to wine production: wood for the traditional barrels used for storage and stainless steel seen in the net that covers the bottles and tanks used for fermentation and aging.
“Haro footbridge connects the wineries and the historical center with an attractive design inspired by a wine barrel stave,” says Pablo Alfonso, Project Manager at Arenas & Asociados.
“It merges tradition with innovation, with the bridge seamlessly blending into the landscape.”
An attractive and durable structure
The Haro footbridge is the first project by Arenas & Asociados to be made of stainless steel. The decision to use stainless steel was due to its durability and low maintenance requirements.
“Duplex stainless steel stands out for its high strength properties and its durability characteristics,”
says Alberto Aliende, Sales Manager at Outokumpu. “This meets the requirements of this project, such as the slender structure and its durability, so we used it for the deck, arches and plate ties.”
Following discussions, Arenas & Asociados decided to use Outokumpu’s sustainable stainless steel in the main structure of the bridge. Commonly used in structural components for floodgates and bridges, the lean-alloyed duplex stainless steel has good resistance to corrosion, making it a more durable substitute for coated carbon steel. It also offers high mechanical strength, which enabled design of a lightweight and elegant structure. Meanwhile, the grade is also straightforward to form and weld, as long as the fabricator takes account of the high strength and welding parameters.
Following discussions, Arenas & Asociados decided to use Outokumpu’s sustainable stainless steel in the main structure of the bridge. Commonly used in structural components for floodgates and bridges, the lean-alloyed duplex stainless steel has good resistance to corrosion, making it a more durable substitute for coated carbon steel. It also offers high mechanical strength, which enabled design of a lightweight and elegant structure. Meanwhile, the grade is also straightforward to form and weld, as long as the fabricator takes account of the high strength and welding parameters.
“Our design is based on a bridge deck that curves outwards, giving it a similar shape to the wooden boards used to make wine casks. The structural solution features a beam of variable depth and width, fixed elastically at its ends by two lateral spans that are considerably shorter than the main span (2.5 m compared to 40.6 m). Its cross-section, trapezoidal in shape and entirely under the deck at the ends of the footbridge, is transformed into a quasi-rectangular box supported by slightly inclined arches (without exceeding the height of the railing) in the central area of the main span. In this way, the main structure of the footbridge starts under the deck at the ends and finishes above it at the center, which corresponds optimally to the bending moment diagram. At the same time, to respect the existing drainage section of the river as far as possible, the area where the structure's depth under the deck is significant is restricted to the ends of the footbridge.”
“Another feature of the design is the use of spherical bearings, which will support a lateral impact on the structure of up to 20 tons in case floating objects such as trees hit the bridge during floods. The handrails feature stainless steel netting in grade AISI 316. This echoes the netting used for Rioja wine bottles.”
Thanks to an efficient structural scheme, the designers have optimized the initial construction and installation costs. Furthermore, using corrosion-resistant stainless steel reduces lifetime maintenance costs and ensures the footbridge will keep looking fresh in the decades to come.
Fabrication
The initial contract and tendering process for the project wasn’t smooth sailing. The tendering process in February 2022 coincided with the war in Ukraine, causing energy prices to soar and creating price uncertainty. Because of this, Haro City Council postponed the project for a few months.
After appointing contractor Orion and fabricator Metalizard, the construction process began in late 2022. As a fabricator who already had extensive experience working with stainless steel for water-based infrastructure, Metalizard was familiar with duplex stainless steel and the welding parameters that were needed.
Once the structure was complete, it was blasted with glass microspheres to acheive a uniform matt surface finish and to reduce the visual impact of the welding. The most visible welds were also smoothed prior to treatment to improve the final aesthetics.
Construction
In parallel, construction firm Orion prepared the site on the Tirón River. This included major groundworks to build the concrete abutments and to reinforce the riverbank to support the weight of the 700 ton capacity crane needed to lift the bridge into position.
Once the steelwork was fabricated, it was delivered to site and lifted into position as a single span weighing 73 tons over a radius of 27 m. This required high precision to ensure accurately placement of positioning pars into plates inside the abutments.
As finishing touches, a lighting system was installed. Small LED floodlights, positioned 2-3 cm above the pavement, are arranged along the edges of the walkway.
A sustainable future
Having opened in December 2023, the bridge is designed to provide a working life of around 120 years. This durability makes stainless steel a sustainable option, which is important as it means its won’t be discarded quickly.
Sustainability in construction has become one of the most determining factors at Arenas & Asociados.
“Arenas is committed with the reduction of carbon footprint in our projects as well as with circularity of materials, following a cradle-to-cradle philosophy, when possible,”
says Alfonso.
The long life of stainless steel helps make the most of the energy used to produce the bridge. “One of the objectives of all our projects is to guarantee the durability of the structures. We believe that the best strategy to achieve this is to eliminate or minimise the maintenance required,” Alfonso explains. “The use of duplex stainless steel on the Haro footbridge means minimal maintenance and provides excellent performance for all of its lifespan.”