Construction is underway on a tunnel as part of a bypass to relieve traffic for communities in Toggenburg, Switzerland. For Doka’s formwork experts, keeping in view the conditions of this project, their new, rentable tunnel system DokaMT is just what’s needed to keep in check the rugged forces of the mountain and to make the tunnel feel like a work of art.
Project: Lochweidli Tunnel
Location: Wattwil, Canton St. Gallen, Switzerland
Building type: Mining-type and cut and cover
Overall tunnel length: About 305 m
Formwork traveller length: 10 m
Project owner: Tiefbauamt Kanton St. Gallen
Construction company: ARGE Weidli (Strabag/Heitkamp)
Formwork operations start: Autumn 2020
Formwork operations end: May 2021
Products: Tunnel system Doka MT, Large-area formwork Top 50
Services: Planning, Pre-assembly, Assembly on site, Formwork Instructor, Disassembly
At the entrance to the tunnel what immediately catches the eye is the Tunnel system DokaMT; a preconfigured formwork traveller, with vibrator, concrete placing boom, pipework, and filler necks; including carpenter-friendly bottom slab formwork and sealing carriages. It is modularly designed according to the construction set principle and comprised mainly of rentable components.
The Lochweidli Tunnel project in the Canton of St. Gallen is 305 metres long and principally of mining-type tunnel construction (a good 30 blocks mostly underground) and has two portals at its entrance and exit points. The short route will be completed this year and will keep transit traffic away from the communities between Wattwil and Ebnat-Kappel as one section of a longer local bypass.
The project is an object lesson in how people enjoy questioning established procedures and, by developing innovative solutions, help to make the world a better place. The story in a nutshell: a few tunnel enthusiasts at Doka spot a niche in the market and develop a system for the unique conditions of the Lochweidli project, which depends on short assembly times and fast cycle times. On easy cleaning of the formwork surfaces, especially under confined conditions. On generous access openings for construction traffic. On a method of construction that flexibly reflected the cross-section of the building space available. Last but not least, on a system which is ready to go just in time, because the steel components involved were delivered completely pre-assembled from Doka’s Amstetten pre-assembly service. Thus, on site rapid results in the assembly process were achieved.
Klaus Mirna, Doka’s site project manager, says, “The Swiss market is fiercely competitive; anybody who wants a piece of the action must be innovative.” Therefore, for Lochweidli, Doka designed a complete solution, which alongside the tried-and-tested standard components (which are indispensable for such contracts), also included a few dozen components, which were specially developed for this tunnel.
DokaMT: A multi-tool among formwork travellers
The DokaMT system, which stands for Mining Tunnel, is highly versatile. It grows in accordance with the requirements of its users. It embodies the principle of function follows form – making it the multi-tool among formwork travellers. And this construction set can in large part be rented as a complete package – in the sense of a circular flow economy where ownership is no longer important and a user fee can be charged based solely on operating time and associated services.
And this is how the DokaMT formwork traveller moved through the tunnel on the previously-laid foundations, doing what it does best: professionally-managed formwork at a fixed price – a solution particularly suitable for straightforward projects in which light can be glimpsed at the end of the tunnel within one year. After about nine months, the job was wrapped up, and the system with its accessories went back to the rental park.
Strabag, the construction company, was pleased because the construction site was quickly cleared, and they had saved themselves the expensive equipment purchase. The fact that the Swiss were persuaded to adopt this innovative one-stop-shop model is also thanks to the Doka headquarters with its Global Expertise Center Infrastructure (GEC) and Research and Development (R&D).
Riesenberger has spent a lot of time developing the new system over the past two-and-a-half years. At the headquarters in Austria a mock-up was built, half as long as the later-developed full-scale formwork traveller, but still fully functional. The engineers fine-tuned every setting, analysed all the component parts, and so, “from a collection of beams and struts emerged a modular construction set which makes it possible to create any desired shape and which can be adjusted to the most diverse cross-sections,” sums up Riesenberger, adding, “As long as it is structurally feasible.” The best part, according to the people at the GEC, was watching the formwork solution grow not only in CAD format, but also under real-life conditions.
Doka is a world leader in providing innovative formwork, solutions and services in all areas of construction. The company is also a global supplier of scaffolding solutions for various applications.