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Wildlife Overpass Rynetel, Suhr



It took a long time to convince people: more than 20 years ago, Stefan Zöllig demonstrated that wood is the right choice of construction material for wildlife bridges. Today, the wooden bridge over the N01 highway between Suhr and Hunzenschwil is impressive.

The wooden structure remains visible from below zoom
The wooden structure remains visible from below
Assembly work at night zoom
Assembly work at night
Assembly work during daytime zoom
Assembly work during daytime
Aerial view during assembly zoom
Aerial view during assembly

The Project

Because traffic routes cut through the habitats of wild animals, the Federal Office for the Environment defined wildlife corridors of supraregional importance. The "AG6" corridor connects the Jura region with the Central Plateau and runs between Gränichen and Suhr over the N01 national highway. Here, the new 50-meter-wide arched wooden structure now enables wildlife to cross the highway safely.

During the planning phase, various construction methods were tested and compared with each other. The renewable building material came out best in this comparison - the decisive factors were the better ecological balance and the faster execution.

The Construction

The wildlife overpass is constructed of prefabricated 156 glulam beams. The girders, each weighing two tons, are 17.4meters long, have a cross-section of 24 by 76 centimeters and are mounted on the cast-in-place concrete walls with steel joints.

The girders are made of Swiss spruce boards and an RF adhesive bonded to keep their shape.

The Challenges

Construction projects over traffic routes are always demanding, because for the assembly of the supporting structure. The highway was reduced to two lanes for only 24 nights from 9:30 p.m. to 4 a.m. each night. Furthermore, a lot of pioneering work was done for the planning of this lighthouse project.

Construction Data

- Spans: 2 x 17.4 meters

- Length: 35.6 meters (across the carriageway)

- Width: 54 meters (lengthwise to the carriageway)

- Bridge area: 1'922 m² 

- Construction timber: 850 m³ spruce, origin Switzerland

Construction costs

- 13.9 million Swiss francs

Services Timbatec

- SIA Phase 31 Preliminary project
- SIA Phase 32 Construction project
- SIA Phase 41 Tender and comparison of offers 
- SIA Phase 51 Implementation project
- SIA Phase 52 Design
- SIA Phase 53 Commissioning
- Expert planning fire protection
- Work planning 3D and 2D

Building Owner
Bundesamt für Strassen ASTRA, Filiale Zofingen
4800 Zofingen

Timber Construction
Häring AG
5074 Eiken


Ingenieurgemeinschaft WUEF;

Bänziger Partner AG, 5400 Baden und

Timbatec Holzbauingenieure Schweiz AG, 3012 Bern


Aravia Bau AG

5303 Würenlingen

Supplier glulam

Hüsser Leimbau AG

5620 Bremgarten


Nils Sandmeier

2501 Biel

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Thun Branch

Timbatec Timber Construction Engineers Switzerland Ltd.

Niesenstrasse 1, 3600 Thun

Tel: +41 58 255 15 10

Zürich Branch

Timbatec Timber Construction Engineers Switzerland Ltd.

Ausstellungsstrasse 36, 8005 Zürich

Tel: +41 58 255 15 20

Delémont Branch

Timbatec Timber Construction Engineers Switzerland Ltd.

Avenue de la Gare 49, 2800 Delémont 

+41 58 255 15 40

Bern Branch

Timbatec Timber Construction Engineers Switzerland Ltd.

Falkenplatz 1, 3012 Bern

Tel: +41 58 255 15 30


Headquarters Vienna (A) 

Timbatec Timber Construction Engineers GmbH
Im Werd 6/31a, 1020 Wien 
Tel: +43 720 2733 01


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