How a UNESCO World Heritage Site is being preserved for posterity

When Zollverein coal mine and coking plant both closed for good in the late eighties, German heavy industry – a pillar of Germany’s success as one of the world’s premier industrial powers during the post-war period, came to a standstill too. In the years from 1961 to 1993, Zollverein ranked as the largest and most modern coking plant in Europe, covering an area of 100 ha and producing up to 8,000 t of coke a day. Together with the adjacent Zollverein coal mine, one of the biggest and most productive black coal collieries anywhere in the world up until its closure in 1986, it became a UNESCO World Heritage Site in 2001 and is a centre for art and culture in the middle of the Ruhr Valley. In order to preserve this impressive industrial monument and make it accessible to visitors, the complex facility has been lavishly maintained section by section for many years now. Due to the very strict regulations governing the protection of historical monuments, everyone involved must take meticulous care not to damage or alter any of the historic building fabric – no easy task for Branch Manager Heiko Esch and Project Manager Rolf Bittner of XERVON, the provider of scaffolding services charged with scaffolding the quenching hall.

“While the scaffolding was being erected, the Zollverein Foundation’s monument conservation officers were on site at least once a week to check every single support, take a close look at every single anchor plate and make absolutely sure that we didn’t modify any of the building fabric”, Bittner reports. “The people responsible for the project were positively surprised each time by how coherently and reliably our solutions were planned in advance on the basis of the detailed 3D scans, and how flexibly we were nevertheless able to respond to last-minute change requests with standard Layher Allround material”, Esch continues. “That was something they’d not previously experienced in this form with other service providers.” It was not only the Layher scaffolding material that laid the foundation for this success but also the decision to measure the entire structure using 3D laser technology and carry out all planning using the data acquired in this way. “Layher and the technical office in Eibensbach provided us with very professional support”, says Bittner. The complete scaffolding was planned in 3D as part of the Layher SIM process using LayPLAN SUITE software tools, so that we were able to solve any challenges upfront during the planning phase. “The project was also something of a trial run for us, in that it helped us see to what extent planning scaffolding in 3D brings real benefits for our everyday work and assess whether it would make sense for our company to purchase the technology ourselves. What’s more, this is the first major project that we were invited to realise on behalf of the Zollverein Foundation. I have to admit we’re impressed! And, even more important, so are our customers”, Esch adds.

Have you ever scaffolded a chute?
On the outside of the quenching hall, the specialists erected 22 m high and 3.53 m wide birdcage scaffolding totalling an awesome 21,900 m³ over a length of 282 m. The scaffold foundation on the sloping, tiled coke chute was a particular challenge. Additional 0.73 m wide support structures were therefore installed along the entire length to absorb any forces occurring. “We weren’t allowed to drill, we weren’t allowed to put too much stress on the tiles and we were obliged to wedge the entire scaffolding in a very elaborate way inside the building”, Bittner explains. “We laid tubes to the inside in order to dissipate the tensile forces in these areas and absorb them on the interior walls.” Layher Allround Scaffolding offers a wide range of solutions for tricky tasks such as this, even in the standard range, and literally enables ‘more possibilities’.

Scaffolding on rails
Inside the quenching hall, three birdcage scaffolding elements – each 8,000 m³ in size and completely wrapped in foil plastic sheeting in places for dust protection – were erected one behind the other, creating safe and readily accessible platforms for carrying out the refurbishing work. Once again, the building had a special challenge in store. A so-called hot alley runs at an elevated level parallel to the tracks inside the building, on which huge railway wagons used to transport coke from the ovens to the quenching tower. From here, the person in charge of the coking plant could keep a watch on the entire process route with the help of a small rail car. Unfortunately, the structural properties of the underground were unclear, meaning the birdcage scaffolding was not allowed to be supported on the floor but had to be built

on the rails with the help of wooden beams. Since the hall is not suitable for lorries, the responsible persons at XERVON had to come up with a solution to get material to wherever it happened to be needed on site. With four rail rollers and some Layher Allround standard material, they set to work building a wagon which can be pushed along the railway tracks inside the hall, turning material transport into child’s play.

A cloud full of points traces the building
Planning in 3D is a good idea whenever the geometry of a building is complex and there are numerous interference contours that make it difficult to erect scaffolding. If no 3D-files of the building exist, they can be generated by a 3D laser scan. Laser beams scan the building from various angles. The software uses the data recorded by the scanner to compute a digital twin of the building in the form of a point cloud in preparation for planning the scaffolding in LayPLAN CAD. An optimally planned 3D AutoCAD model and 2D assembly drawings are the result. All obstructions or problematic geometries can then be identified in advance and both the assembly procedure and the required material planned accurately. “That way, we don’t have to engage in any do-it-yourself on site, which is frowned upon and above all time-consuming”, Bittner comments. “On top of that, it prevents missing material from bringing work on the construction site to a halt for long periods. The slightly longer time and greater effort for planning are more than offset by the easy installation.” The entire process – from planning through site and material logistics to erection – was stored as a digital image during the Layher SIM (Scaffolding Information Modeling) process. Layher offers the software needed for this purpose as part of the LayPLAN SUITE software package, for instance. Layher SIM has manifold benefits. Amongst other things, it enables a quick and trouble-free mounting of the scaffolding, which leads to more planning and scheduling certainty as well as increased profitability in every project. In complex construction projects, Layher SIM can also be combined with BIM (Building Information Modeling), leading to more transparency for all trades.

Services for industry
XERVON GmbH is part of the REMONDIS Group and has been a leading international supplier of industrial scaffolding and insulation services for over 80 years, with sister companies offering specialist surface technology and maintenance. The Bottrop branch is responsible for the project at Zollverein coking plant in Essen. “We have about 200 scaffolders of our own here plus quite a few subcontractors, and our work is mainly for industrial clients throughout the Ruhr District”, explains Branch Manager Heiko Esch. “XERVON’s Scaffolding division was originally an independent scaffolding specialist and even then, we worked exclusively with Layher material. Today, we still have material from those early years in stock and we continue to use it as a matter of course. The scaffolding systems are designed to be compatible, and because they’re also highly durable and can be purchased for decades afterwards, Layher’s Integrated System represents an exceptionally secure investment for us. When it comes to satisfaction, here’s nothing more to be added.”