Climatic conditions at timber overpasses for wild animals

Background

Timber is now also being used in the construction of overpasses for wild animals in Switzerland. The initial positive experiences and findings from four overpasses for wild animals constructed in Germany since 2005 have provided a solid planning framework.

Woods with higher natural durability, such as larch and Douglas fir, were used for these overpasses in Germany. But they are not available regionally in sufficient quantities in Switzerland for structures of this nature and scale. A chemical wood treatment is being used to improve the durability of spruce and fir trees available in Switzerland. However, this raises the issue of whether the use of chemicals is really necessary.

Goals

The project aims to record and scientifically evaluate the general climate conditions by systematically monitoring the climatic and humidity conditions at the structure. Special emphasis is placed on the impact of traffic. The timber construction is exposed to large volumes of water from spray clouds. On the other hand, the traffic has a positive impact on air change (flow) in the structure and on its drying capacity.

The impact of the cross-sectional shape and design of the tunnel-like bridge structure on the moisture levels and drying speed of the wood will also be analysed.

Procedure

The outstanding issues will be resolved as part of a comprehensive analysis of climatic conditions at overpasses for wild animals through long-term monitoring, laboratory testing and simulations. The results will be presented in an application-oriented research report with observations on the design of timber overpasses for wild animals.