New BBZ BL building in Muttenz
February 25, 2026
At the cantonal school site Kriegacker in Muttenz, three upper secondary schools will be brought together in the coming years to form the Polyfeld Muttenz upper secondary campus. These are the Baselland Vocational Training Center (BBZ BL), Muttenz High School and the Center for Bridging Courses. The Secondary II Campus Polyfeld Muttenz will be realized in three stages.
For the canton of Basel-Landschaft, ERNE is responsible for parts of the dismantling and the master builder work in stage 1 - BBZ, consisting of the workshop building, assembly hall and sports hall as well as the renovation of the existing tower, which will house the classrooms in future.
Complex demolition for the new Polyfeld Muttenz secondary school campus
As part of the site preparation, existing buildings were demolished in collaboration with Aregger AG Bauunternehmung. The renovation and gutting of the tower, which was carried out from top to bottom by ERNE decon, was particularly challenging. At the same time, the pollutants were removed. The demolition work then began. Over an area of 20x20 meters, the core zone of the 12-storey building - including core walls, staircases, down to the floor slab and the existing foundations - was completely dismantled.
Due to noise protection, the dismantling of the glass façade could only begin after the gutting of five floors had been completed. For the demolition of the façade, the team developed a special load suspension system to safely remove the façade elements weighing up to 2.5 tons with the construction crane.
Additional reinforcement measures were implemented inside the building to provide the necessary bracing during the construction phase. Four steel frame constructions with transverse bracing, each weighing around three tons, were required on each floor level to safely transfer the load. This temporary construction will be completely dismantled once the conversion and new construction work is complete.
New construction of the building core and the main staircase in the tower
The previously gutted tower building will be given a new building core during the new construction phase. Existing parts of the building will be connected to the new core via circumferential shrinkage alleys. The walls, ceilings, emergency staircases and the central main staircase will be constructed in high-quality exposed concrete floor by floor. The wall and ceiling work is being carried out in parallel: as soon as the first walls have been concreted on one half of a floor, work on the ceiling begins there - while the walls are being built at the same time on the second half. Once all floors have been completed and the core has been finished, the shrinkage alleys are closed and the temporary sprinkling removed.
A highlight of the tower building is the main staircase: it consists of individually manufactured precast concrete elements. The steps are freely suspended and taper downwards. The open space between the individual steps emphasizes the filigree construction and gives the staircase a light, almost floating effect. As the undersides of the steps remain visible, the implementation requires the utmost precision in planning, production and installation.
New building complex with high technical precision
All buildings in stage 1 - BBZ will be constructed in high-quality exposed concrete. A special exposed concrete concept is used to ensure a smooth, even and uniform concrete surface throughout. Precise execution and concreting stages of exactly the same size create a harmonious and uniform appearance. The special formwork required for this is produced by our sister company HUSNER AG Holzbau on a project-specific basis.
The new 55 meter long and 26 meter wide workshop building is being constructed in three stages. The staging concept allows simultaneous processing of walls, columns, earthquake walls and ceilings per storey - an efficient construction operation that combines precision and speed.
At the same time, the new modern triple sports hall is being built, which is characterized by a complex structural solution: A total of 25 prestressed prestressed concrete beams are being installed - including 21 single beams and two double beams. In the area of the double girders, the hall can later be flexibly divided into three smaller units. ERNE AG's VDC department created a detailed 3D model for optimal planning and execution.
The beams are built in sections: The structural engineering team builds two girders on the left and two on the right at the same time. Once all the girders have been completed, the ceiling is concreted and provisionally supported with tree trunks. The prestressed concrete beams are then prestressed, giving the entire structure its final stability.
In a first step, the ceiling of one half of the hall was assembled with twelve girders and prestressed. The shoring system was then moved to the second half of the hall, where the remaining beams were installed and also prestressed. Another architectural highlight of the sports hall is the external spiral staircase. A specially developed formwork will be used for its construction, which is precisely tailored to the individual requirements of the staircase.
The future assembly hall canteen will be connected to the sports hall on the west side. The building will be constructed from prefabricated elements and combines aesthetic exposed concrete with a timber composite ceiling, executed by ERNE AG Holzbau.
Once the construction work is complete, the three parts of the building will be functionally and structurally connected.
Safely planned - safely dismantled
Thanks to thorough work preparation (AVOR), the team developed a safe and efficient procedure for the dismantling of the temporary sprouting of tree trunks. Depending on the location and load, 100 of the 125 logs with a total length of 9.5 meters had to be pre-cut before being moved. The team carried out the removal from a safe distance using the remote-controlled Brock 500.
The entire work process was recorded in advance and communicated to all employees as part of a safety instruction ("toolbox"). This ensured that nobody was in the danger zone during the dismantling work.
