From idea to implemented bridge concept in public space

The built environment needs sustainable solutions. One possibility is to build less and preserve what we already have. But when building, we need to do it less resource-intensively. One example is using renewable materials, such as wood, as the main load-bearing structure in lightweight bridges. However, this requires careful planning, detailed design, and execution, precisely the challenge that the winning concept idea, Bifrost, took on in 2022. 

Lightweight bridge wins innovation contest

Roberto Crocetti, an adjunct professor at KTH and founder of TBS, Timber Bridge Specialists, proposed a bridge with unique properties that is lightweight and easy to assemble and dismantle. Two years ago, when the opportunity to participate in InfraSweden's innovation competition to design lighter pedestrian and cycle bridges arose, it was apparent to pursue the idea by an application.

Crocetti formed a team of KTH, TBS, Funkia, Gaia Architecture and the City of Stockholm for the project application. Together, they refined the original bridge idea, resulting in the Bifrost concept, which won the competition.

KTH refines the idea for implementation

The win for Bifrost also meant the opportunity to apply for a project grant from InfraSweden to refine the idea. The grant was awarded and paved the way for KTH to further study some of the concept's innovative elements from a technical and architectural perspective. The grant financed a course project and two degree projects that could develop essential components for implementing the bridge in the public space. 

Since this spring, a finished bridge designed according to the Bifrost concept stands in Uddebo, Tranemo municipality. Plans for further development of the concept are underway.

"After the innovation competition, we were commissioned to design, supply materials and supervise the assembly of a real timber bridge in Uddebo in early 2024. It has been a speedy delivery from the initial idea to the realisation of the concept," says Daniel Honfi, a structural engineer at TBS Timber Bridge Specialists and leader of the innovation project."

Text: Johanna Bernhardtz   

Learn more about the project

The Bifrost concept

The bridge is developed to suit different contexts and, thanks to various spans, can be easily adapted to site-specific needs. It is a pedestrian and cycle bridge constructed over 90% by volume in wood, nature's lightest construction material. The relative lightness of the bridge also makes the approach more flexible. Much effort has focused on minimising material use and reusability. Therefore, each bridge element can easily be replaced without dismantling the bridge.

Since spring 2024, a fully implemented lightweight bridge has been in place in Uddebo Tranemo municipality. Here you can see a short film about the installation.

Project partners

KTH Department of Civil and Architectural Engineering , Stockholms stad Trafikkontoret , Timber Bridge Specialists , Gaia Arkitektur  and Funkia .

The innovation project

The Strategic Innovation Programme InfraSweden  issued the InfraLIGHTER Awards  innovation competition in collaboration with its sister programme LIGHTer . 2022. The SEK 500,000 project grant from InfraSweden contributed to funding a course project, two degree projects, and a doctoral student project at KTH, within which they redeveloped some of the essential bridge concept elements.

Read the two degree projects: Novel steel hinge connection for pedestrian timber bridges: Novel steel hinge connection for pedestrian timber bridges  and Hybrid bridge deck of timber and corrugated steel plates

Read the jury's motivation  and watch a film presenting the project.