Feasibility study on heavy duty timber bridges

Switzerland’s goal of becoming climate-neutral by 2050 calls for sustainable solutions on transport routes – for example, in the form of heavy-duty bridges made from timber. The study explores the specific implementation of such structures.


  • Lead school School of Architecture, Wood and Civil Engineering
  • Institute Institute for Timber Construction IHB
  • Research unit Timber Structures group FGH
  • Funding organisation Schweizerische Eidgenossenschaft (Bundesverwaltung)
  • Duration (planned) 01.01.2022 - 31.12.2023
  • Project management Prof. Dr. Steffen Franke
  • Head of project Bettina Franke
  • Project staff Bettina Franke
    Joel Philippe Karolin
    Prof. Dr. Christophe Sigrist
  • Partner VSL (Schweiz) AG
    Timber Structures 3.0 AG
    Timbatec Holzbauingenieure Schweiz AG
    Holzbauexperten GmbH
    Flück Holzbau AG
    Zaugg AG Rohrbach
    CNC Holz


Switzerland has a 2,254.5-km network of national highways with a total of 4,270 bridges on the main axes or serving as overpasses (Federal Roads Office FEDRO annual publication, 2020). The national highways network has a very high density of bridge structures with around two bridges per kilometre of transport network. A survey on road bridges conducted by BFH for the period 2010 to 2014 indicated that the supporting structure of just 3% of these bridges contains timber. The feasibility study aims to produce the first designs and solutions specifically for heavy-duty bridges made from timber.

Course of action

Timber and the wide range of timber-based products and technologies hold potential for use in heavy-duty bridges on the road system. The project aims to produce box-girder sections made from concrete in combination with pre-stressed timber technology for extensive use on heavy-duty traffic routes. Society is willing to change and to commit to achieving a climate-neutral Switzerland by 2050. Research and industry need to find new high-performance solutions for the construction sector. A parametric model will be developed to determine the optimal load-bearing and deformation behaviour on the transversal and longitudinal axes of bridges. The use of pre-stressed technology with tendon profiles, the number of harnesses and the anchoring system will be tested on the model/experiment. An initial working model close to the original scale will be used to assess practical aspects of implementation.

Grafik zu Holzbrücken im Blick der Zeit und Entwicklung.
Holzbrücken im Blick der Zeit und Entwicklung
Visualisierung der Anzahl Brückentragwerke im Schweizer Nationalstrassennetz, basierend auf einer Studie anhand der Baugesuchsdaten zu Materialien in Brückentragwerken in den Jahren 2010 bis 2014.
Visualisierung der Anzahl Brückentragwerke im Schweizer Nationalstrassennetz.
Entwurf eines zukünftigen Brückenquerschnittes in Holz.
Entwurf eines zukünftigen Brückenquerschnittes in Holz.