NOE®tec – Branich Tunnel
Branich Tunnel: NOEtec – an ideal formwork system for engineering structures
Two completely different tasks fulfilled using the NOEtec system
The 1796 metre long Branich Tunnel was built as part of the bypass of the town of Schriesheim, Germany. For the construction of the tunnel, NOE-Schaltechnik designed two formwork carriages based on NOEtec, the company's extremely flexible formwork system for engineering structures. Each formwork carriage had its own, quite different, task and some parts had to be adjustable in size.The 1796 metre long Branich Tunnel is under construction in Schriesheim – located north of Heidelberg on the Bergstrasse – as part of the town's bypass. Some 1600 m of the tunnel is being built using traditional tunnelling techniques and 200 m in cut-and-cover construction. The decision was made to use the NOEtec and NOEtop formwork systems from NOE-Schaltechnik, Süssen, for the cut-and-cover sections.
NOEtec and NOEtop
NOEtec is a beam formwork and scaffolding system consisting of a manageable number of individual elements that can be combined in any number of ways. The system is so flexible, it can be relied upon to provide a structure-specific solution on any construction site. This claim was put to the test particularly well on the Branich Tunnel. On this site, the system was used at four different locations for two different tasks: at two tunnel portals – the portal decks were concreted using a self-propelled NOEtec deck formwork carriage. And in the emergency bays inside the tunnel – a NOEtec reinforcement carriage played a crucial role.
NOEtop is a wall formwork system that excels in particular because of its large panels. Its largest panel, one of the largest on the market, has an area of over 14 m². The steel frame formwork can resist a concrete pressure of 88 kN/m² and is therefore highly robust. Thanks to the system's integrated bracing, it can be used as beam formwork in which the tie bars can be placed anywhere in the bracing.
NOEtec deck formwork carriage
The two tunnel portals were constructed using the cut-and-cover method. Main contractor Ed. Züblin AG, Stuttgart, opted for the NOEtop formwork system. To construct the decks as quickly as possible, the site team relied on a NOEtec deck formwork carriage, which the NOE engineers designed and dimensioned specifically for this task using various NOEtec system components. The carriage was approximately 10 m long, 9.6 m wide and 6 m high. NOE H 20 timber beams supported on NOEtec transverse beams were used as boarding supports for the NOEform facing. This arrangement allowed a deck approximately 100 m² in area to be concreted in one operation. After the concrete had hardened, the formwork carriage was lowered hydraulically by about 20 cm and then moved on to the next section. The contractor used NOE LS 200 heavy-duty props to provide temporary support for the deck.
Although a NOEtec formwork carriage looks comparatively slender, it is capable of carrying enormous loads. For each concreted section of the Branich Tunnel, the deck formwork carriage had to support a load of about 360 tonnes.
NOEtec reinforcement carriage
Quite different requirements were demanded from the reinforcement carriage, which was also designed based on the NOEtec system. It was used in the two emergency bays within the tunnel tubes as a mobile working scaffold. The 14 m wide, 10 m long and 9 m high carriage supported three working platforms from which the reinforcement was fixed. It was used five times in each of the two emergency bays. Which meant that after the first bay was complete the carriage had to be moved on to the second. This was not as simple as it might appear at first glance, because the tube cross section here is approximately 2.5 m wider than the standard width in the rest of the tunnel in order to accommodate the emergency bays on the left and right of the carriageways.
As on all construction sites, time is a precious commodity, so the NOE engineers ensured that the reinforcement carriage did not have to be completely dismantled in order to fit through the smaller standard tunnel cross section to reach the second emergency bay. For this reason, they designed the reinforcement carriage in such a way that the top working platform could be lowered and the middle platform folded in sideways.
This allowed the reinforcement carriage to be simply and easily driven to the second emergency bay and then "unfolded" to the required size.
NOEtec system advantages – short installation times
The use of the NOEtec formwork carriages in the construction of Branich Tunnel is a further example of the flexibility of the NOEtec system. In addition, the system impressed the site team with its short installation times and intrinsically self-explanatory construction. The two carriages, one for the deck formwork and one for the reinforcement, took only about 7 working days each to set up on the Branich Tunnel project. Both NOEtec carriages were designed to allow the site vehicles to pass unhindered through them and therefore caused no interruption to construction operations in the tunnel.
NOE-Schaltechnik therefore made its contribution with its flexible NOEtec system to ensuring that the Branich Tunnel will be completely finished and the traffic situation in Schriesheim considerably relieved by 2016.
- Client: State of Baden-Württemberg, Karlsruhe Regional Authority
- Main contractor: Ed. Züblin AG, Stuttgart