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Simple. Smart. Safe
Division IU Tunnelling, Ed. Züblin AG
A smart solution to create two new rescue tunnels in one of Germany’s oldest and most critical road tunnels.
To improve safety standards
The goal was to provide a solution which would bring the rescue tunnels in line with contemporary standards and potentially even save lives in the longer term.
The new rescue tunnels will reduce the length of the escape routes from the 622m long Lämmerbuckel Tunnel.
Planning and design was paramount in this project – particularly with the heavy focus on safety. MEVA was required to design and help execute a bespoke solution with minimal disruption to the existing tunnel.
- Collaborative planning
MEVA assisted contractor Ed. Züblin AG with the detailed planning of this highly demanding construction project, providing both creative standard solutions and specially designed formwork.
- Innovative 3D design for a bespoke solution
In terms of construction, the only significant difference between the two rescue tunnels is their length. This allowed use of the same formwork for both.
The first step was to construct the end walls connecting the rescue tunnels to the existing road tunnel. To form the junction with the arch of the new mined tunnel section, specially designed formwork was designed for the top part of this connecting wall.
The single-sided formwork, comprising Mammut 350 wall formwork and special components, was to be held in place by the STB 300 support frame, which is suitable for pour heights up to 3.30m. Detailing of the special formwork also provided for incorporation of the required internal waterstops.
- Rucksack packed and ready to go
The first section of the rescue tunnel directly adjoining the end wall contains a niche for the electrical installations, where the standard tunnel profile widens out. The solution adopted by the contractor to meet the exact dimensional requirements involved the use of “rucksack” formwork, precision-fabricated by MEVA’s engineers.
To ensure precise mounting of the special semi-circular unit on the formwork carriage and in the tunnel niche, the rucksack formwork was first positioned in the reinforcement. The formwork carriage was brought into place and accurately aligned below it.
The pre-fitted connectors were then tightened in order to firmly secure the special assembly to the carriage. Rubber sections attached to the formwork provided the necessary waterproof barrier between rucksack formwork and carriage.
- Smooth transition
At their ends, the mined sections of each rescue tunnel join onto a further cut-and-cover section. To form the junction between the two different profiles, MEVA’s formwork engineers designed special timber units. These served as a means of securing the waterstops in the transitional section and as formwork for the junction between the round and rectangular tunnel profiles.
Here, the special timber forms were applied as a facing to the Mammut 350 wall formwork and were later reused as stop-end formwork in the cut-and-cover tunnel section. Mammut 350 was then used for all remaining operations. With a fresh concrete load capacity of 100kN/m², the product is ideal for civil engineering applications while also offering a wide range of panel sizes from 1.25m x 0.25m to 3.50m x 2.50m.
- Levelling out to a successful project end
The tunnel inverts were formed using horizontally placed wall formwork units. With no vertical extensions needed to build the 3m high walls thanks to the large Mammut 350 panel sizes, the rest of the works proceeded apace.
The formwork was positioned and supported by EuMax props, fixed diagonally to the excavated pit slope. Their flexible extension length and large range for fine adjustment allowed trouble-free setting.
The walls for the outer sections of the two tunnels were completed in three and four cycles respectively. Mobile MEP slab tables with MevaFlex were then used to cast the ceiling slabs. The two rescue tunnels terminate in diagonal wing walls with canopy. These primarily serve to retain the ground and create a level entrance to the tunnels.
Site manager Alfred Elst was very satisfied with the completed works and had a special word of praise for the carefully targeted, practice-oriented formwork design [see testimonial below]. At the ground-breaking ceremony for the tunnels, Wolfgang Reimer, President of Stuttgart Regional Council also stressed the importance of this project:
Given the importance of Germany’s A8 motorway as an east-west corridor in the national network and its high traffic volumes, proper tunnel safety can save lives in emergencies
Wolfgang Reimer, President of Stuttgart Regional Council
The rucksack formwork developed by MEVA was a perfect fit and the 3D drawings were also very useful. They show the details very clearly and simplify formwork assembly.
Alfred Elst, Site Manager, Division IU Tunnelling, Ed. Züblin AG
- Mammut 350 wall formwork
- STB 300 support frame
- MevaFlex slab formwork
- Shoring system MEP
- Special designs
Division IU Tunnelling, Ed. Züblin AG
Rescue tunnels in Lämmerbuckel Tunnel
Motorway A8, Wiesensteig, Germany
Engineering & Support:
MEVA Schalungs-Systeme GmbH, Haiterbach, Germany
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