In Třebíč, an unassuming experimental bridge may point the way towards a cheaper and more sustainable transport infrastructure in the Czech Republic. Built for CZK 16 million, it cost roughly half as much as a comparable reinforced concrete structure. Scientists are using the bridge to test how the long-proven durability of wood can be combined with modern 3D concrete printing and digital sensors.

A Bridge That Monitors Itself

The project, led by Roman Fojtík from the Faculty of Forestry and Wood Sciences at the Czech University of Life Sciences in Prague, aims to develop a new type of timber-concrete bridge structure with real-time monitoring of its condition and performance.

Moisture is one of the greatest risks for timber structures. It can be present inside the material, where it is difficult to measure reliably. If wood is not sufficiently dried, it may swell, shrink or deform. The resulting cracks can weaken the structure, reduce the material’s strength or create conditions in which wood-decaying fungi can spread. To address this, the research team has developed an online monitoring system that works much like the bridge’s nervous system.

The sensors track not only moisture levels in real time, but also excessive loading and the risk of ice forming on the road surface. “We currently monitor 62 bridges around the world, both remotely and on site, and we know exactly what condition they are in,” says Fojtík. The innovative use of an “ordinary” material such as wood can significantly reduce the environmental impact of construction. With continuous data and timely maintenance, the service life of a bridge can be extended by decades, avoiding millions of crowns in costs linked to premature demolition and waste disposal.

While ageing concrete bridges often have to be demolished, timber structures offer another option. Wood is renewable, stores carbon and allows individual components to be replaced relatively easily. It is also a material with remarkable structural durability, as shown by centuries-old bridges in the Czech Republic that are still in use today.

3D Concrete Printing on Wood

In conventional construction, formwork is first built and then filled with concrete. At the Laboratory of Robotics and 3D Printing at the Faculty of Civil Engineering, Brno University of Technology, however, concrete is applied directly by a robotic arm.

“The biggest challenge in 3D printing was getting the concrete mix to flow properly around the connecting screws. We had to calculate and set the nozzle path so that it passed precisely around the screws without colliding with them. Another challenge was designing the concrete mix so that no voids formed around the angled screws and the individual components of the mixture did not separate,” explains David Bečkovský, head of the Laboratory of Robotics and 3D Printing at the Faculty of Civil Engineering, Brno University of Technology.

In addition to 3D printing, the researchers are also exploring other prefabrication methods, including automated installation of coupling screws and robotic concrete casting on curved surfaces. The composite connection must be both strong and dimensionally stable.

Advanced Research Meets Industry

The project has already produced a number of practical solutions and technologies, from specialised timber sealing and new concrete mixes to a waterproofing system and a Building Information Model designed to monitor the bridge throughout its entire service life.

One of the key outcomes is a proposal for technical regulations for ČKAIT. For the first time, these regulations define standards for monitoring internal moisture in load-bearing timber structures. The researchers have also filed a patent for a unique measurement system capable of detecting the risk of rot long before it becomes visible on the surface.

To help bring these innovations to Czech roads as quickly as possible, the research team worked directly with manufacturers and construction companies. Together, they have shown that when traditional materials are used intelligently and with sustainability in mind, they can fully meet the demands of modern construction.