Bridges that test the limits of physics

Bridges that test the limits of physics

The challenge of overcoming distances has led engineers to develop surprising and complex solutions, which find their ultimate expression in bridges. In this review we encounter both impressive examples of recently built bridges and the innovative methods used to erect them.

Considered a major work of the 21st century, the Millau Viaduct (Aveyron, France) has the tallest pillars in the world and surpassed the Eiffel Tower as the tallest structure in France. Credit: Richard Semik.


The Romans developed the first hydraulic cement, a compound that included lime and volcanic ash, which explains the strength of their bridges, some of which have remained standing for more than 2,000 years. The Industrial Revolution took bridge building to a new level with the development of the railway. Nowadays, engineers and architects continue to push the boundaries of physics and imagination with amazing, sustainable, and even "smart" bridges.

The king of records: the Millau Viaduct (2004)

The Millau Viaduct in the Aveyron region of France is a world icon that illustrates this spirit of achievement, thanks to the various records it holds. The pillars that support it are the tallest in the world, so high in fact that the Eiffel Tower (which measures 324 metres) could fit comfortable under the centre of the structure (343 metres).

Its construction process was a true feat of technology in which highly advanced procedures were used, such as self-climbing formwork (which avoids the use of cranes) and high-strength concrete. The project, designed by architect Norman Foster and engineer Michel Virlogeux, took thirteen years to complete and required three years of construction.

One of the world's largest floating cranes was used to help lift the Gateshead Millennium Bridge (UK), a unique structure example of efficient design. Credit: Wikimedia Commons.

A tilt bridge: Gateshead Millennium Bridge (2001)

Bridge engineering has also evolved in terms of the interaction possibilities of structures with the environment. The Gateshead Millennium Bridge, a unique structure, has won numerous awards for its design since it was opened in 2002 to link the cities of Gateshead and Newcastle.

Designed by Wilkinson Eyre and Gifford & Partners, it is the only tilt bridge in the world that uses a hydraulic system capable of tilting it upwards in 5 minutes to allow ships to pass underneath. It is an example of efficient design, as most of the structure (weighing around 800 tonnes) was built off-site and then lowered into position with the help of one of the world's largest floating cranes. The steel arches that form the bridge are spaced at a 90-degree angle and are tilted upwards in one piece by the force of eight electric motors.

The Tsing Ma Bridge Suspension Bridge (Hong Kong) is a typhoon-proof design feat that is also continuously monitored to optimize similar structures. Credit: Wikimedia Commons.

Big Data and typhoon-withstanding aerodynamics: Tsing Ma Bridge (1997)

Another very unique bridge, also made of steel, is the Tsing Ma Bridge. In use since 1997 and with rail traffic included, it connects the roads that lead to central Hong Kong, the airport and the northwest parts of the city, using an advanced traffic control and surveillance system (TCSS).

Located in an area subject to strong gusts of wind and even typhoons, it required numerous wind tunnel studies and several scale replicas to learn how the structure would behave in the face of a powerful storm. Currently, Tsing Ma is the ninth longest suspension bridge in the world, and the longest railway bridge on the planet. Its behaviour against winds is constantly monitored, and generates valuable information on how to optimise new designs and to learn, thanks to Big Data, how to improve its structures.

The TU Wien “Umbrella” bridge (2020): the smart construction without a crane

Facilitating the process of building a bridge requires as much or more expertise than optimizing its behaviour once built. Between 2010 and 2020, the University of Vienna developed a revolutionary system for deploying a bridge at its final location, inspired by the opening mechanism of an umbrella, a very promising technique for building in difficult terrain and in nature reserves.

The TU Wien bridge, which was erected during the construction of the Fürstenfeld motorway in Austria, used this technique, also called the balanced lowering method (as it is technically known). This system allows large structures to be erected in a few days, as they are not mounted horizontally, but in a vertical position and then rotated. In this way, as no scaffolding is needed, not only time, but also money and resources are saved.

The TU Wien bridge was erected on the Austrian Fürstenfeld motorway without the support of cranes or scaffolding, using a system that mimics the opening mechanism of an umbrella. Credit: TU Wien.

Technologies such as those that support these deployable structural systems, together with tools such as Big Data or the incorporation of innovative materials, promise to challenge the laws of physics to unsuspected limits. Solutions that enable not only the erection of durable structures, but also the construction of bridges in harmony with nature, respecting the environment and learning from the natural surroundings.

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Tungsteno is a journalism laboratory to scan the essence of innovation. Devised by Materia Publicaciones Científicas for Sacyr’s blog.


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