The purpose of bridges is to overcome boundaries. Kusser’s post-tensioned granite bridges take that definition literally. They provide spans of up to 20 m, at thicknesses of a mere 15 to 50 cm, with no additional structures, coverings, or coatings. Refined engineering connects two banks in a more environmentally friendly way than ever before. So for us, sustainability begins with material selection. Our granite is extracted from our own quarries. There is no need for kiln firing, concrete casting, or chemical treatment. This means that our post-tensioned granite bridges simultaneously deliver an unbeatably low climate footprint and an important innovation, ensuring an investment in future-proof infrastructure. What we build today, should still be here in many generations’ time.
With a total weight of some 77 tonnes, the structure spans 20 m with a low construction height of just 50 cm. This makes it the longest single-span, load-bearing, post-tensioned granite bridge ever built. Unteriglbach, Ortenburg - 2021
Benefits
Factory-finished
During construction and assembly in the factory, our bridges undergo 100% quality checks - each segment is produced with millimetre-accuracy, the steel tendons set accurately and the rails integrated.
Quick installation
The bridges are supplied completely pre-assembled and are installed in just one crane day.
Barrier free
Almost without joints, slip-resistant, and with no ramp: Our bridges enable barrier-free crossing without any additional measures; if required they can also carry emergency vehicles.
Flood water protection
The slenderness has more than just aesthetic advantages: It provides increased freeboard during flooding. Railings can, like in Neuhaus am Inn, be designed for quick removal if extreme weather events threaten.
Versatile
Alongside the economic aspects, there is the visual aspect too. Deployable from just 15 cm construction height, post-tensioned granite elements are also a genuine alternative to precast concrete components in innovative projects. As architectural elements, such as a balcony for a townhouse, through to ceiling elements.
DIBt approval Z-13.4-150
The bases are solid granite segments, joined together with high-strength post-tensioned steel. Granite's extremely high compressive strength means that the resulting composite material is extremely resistant, structurally stable, and aesthetically pleasing. However, the slender look is not the only advantage.
A new approach to economy
With a service life of well over 100 years, granite bridges are well worth it in the long term: They combine low operating costs with high durability and a timeless, modern appearance. Additional protective layers or coatings are not required because the granite itself provides both the load-bearing and visible elements. Doing away with costly maintenance makes these bridges particularly attractive to municipal customers.
Post-tensioning technology for foot and cycleway bridges with use-dependent railing heights: 1.1 m for footbridges and 1.3 m for cycleway bridges. Lateral installation provides additional clear width.
Assembly & installation
Planning
Each bridge is planned individually to comply with customer demands. Requirements regarding load-bearing capacity, railings, and path connections are included in the project planning phase, then considered by our engineering team.
Manufacture
The manufacture of post-tensioned granite bridges begins with raw blocks of Tittling fine-grain granite from our own quarry. These are sawn into individual segments with the required surface treatments. The required space for the tensioning steel wire strands is milled in the middle pieces or drilled in the side sections. Then the individual elements are glued together and tensioned. After this the holes are sealed and the railings fitted.
Preparation
At the start of installation, the site-provided abutments are measured with millimetre accuracy. Grouting frames are used to compensate for construction tolerances. These are installed before placing of the bridge on the abutments. Likewise, temporary supports and lashing points are also fitted to facilitate installation.
Insertion
The bridge is lifted onto the abutments using a truck-mounted crane. This is the most spectacular installation step in the entire project, one that is usually watched avidly by customers and passers-by alike. This is followed by the pouring of elastomer bearings and, if necessary, installation of the connecting stones.
Finishing work
The temporary steel supports are removed and, if necessary, expansion joints installed to ensure the bridge is finally ready for use.
Slenderness is our strength
Post-tensioned granite bridges can be constructed with a construction height of just 15 cm and provide a barrier-free, joint-free, and non-slip crossing. By comparison, a paved reinforced steel concrete bridge is almost twice as thick as one of Kusser’s post-tensioned granite bridges. Equally, there is no need for corrosion protection, coating work or regular repairs. They are suitable for use as foot and cycleway bridges and can be designed to support loads of up to 20 tonnes, for example for emergency vehicles, but are equally suitable for use as above-ground civil engineering structures.
Tested, approved and proven.
More than 100 bridges in Germany and internationally, including in Stevenage close to London serve as proof of the practicality and versatility of post-tensioned bridges. They have been subject to regulatory approval by the German Institute for Building Technology (DIBt) and been awarded construction technique permit number Z-13.4-150.
When you speak with Maximilian Alls, you are speaking with an expert. As a civil engineer and fully qualified stonemason, he knows our products from both a technical and practical perspective. He looks forward to your questions and to working with you on future projects.
