Casais Group received the honour of the National Urban Rehabilitation Award for execution of the “Rehabilitation of the Lower Deck of the Luiz I Bridge over the River Douro” public works project in the Best Structural Rehabilitation category.

This intervention consisted of reinforcing the existing metal structure and building a lightweight reinforced concrete deck, supported on new metal carlings and stringers that entirely replaced the old ones. The characteristic architectural component of the Luiz I Bridge was a fundamental factor in the design, with both the shape and composition of the pavements and the railings having been preserved and merely reinforced. The cast iron lamps that once existed have been completely restored, preserving the aesthetic value of the legacy the Luís I Bridge has traditionally represented.

Intervention was also required as regards the mechanical functioning of the bridge, since the four support braces, common in the construction of metal bridges of the time, were upgraded and the dimensions and characteristics of the materials initially used were maintained. An oleodynamic system was added to the bridge deck, the main purpose of which is to cushion the oscillating effects caused by Porto-Gaia traffic, both on the lower and upper decks

This rehabilitation is a one-off project, designed specifically for this project, but it does serve as a model for future similar rehabilitations of other Parque das Pontes works on Portuguese metal bridges. It was also important to use older, proven, techniques in the restoration of these works of art, as was the case with the riveting setting process used in this restoration.

In addition, the use of innovation and technology, with the assistance of 3D modelling during works preparation, and a focus on sustainability were priorities in this project. In cases where it was not possible to repurpose the materials because they were too damaged or could not be reused, they were recycled for incorporation into future projects.

Bearing in mind that the bridge is classified as a Portuguese Property of Public Interest and is also included on the UNESCO list, the solution for its rehabilitation took into account the “Recommendations for the Analysis, Conservation and Structural Restoration of Architectural Heritage” of the International Council on Monuments and Sites (ICOMOS) that apply to this type of construction.

Now in its 12th year, the National Urban Rehabilitation Award sought to give recognition to urban interventions that have multiple features that offer added value to society, analysing factors such as their contribution to the improvement of cities and their impact on the community, their success measured by market acceptance, social impact and value and their potential to induce change in the urban fabric. This award highlights projects that focus on heritage restoration and works demonstrating particular innovation in structural rehabilitation.

“We are verry proud of this intervention because the Luiz I Bridge is one of the greatest icons of the cities of Porto and Vila Nova de Gaia and has had an incredibly significant impact on both the development of tourism and commercial activity in these cities. Many of the numerous Portuguese metal bridges, whether rail or road bridges, are over 100 years old. It is very important to use proven techniques when repairing and reinforcing century-old ferrous materials that cannot be welded so that we maintain the aesthetic value of the heritage.

We believe that this award recognises our dedication to this project and what we see as good practice for the sector,” says António Carlos Rodrigues, CEO of Casais Group, the engineering and construction company that built the project.