Case Study

The consortium Klebl & Bauer built a station of about 90 meters in length and two areas of switches in the immediate vicinity of houses and apartment blocks.
The new Hardh the station on the Fürth underground line was completed in December 2006. The project plans of Klebl are now available to the operators of the underground railway in digital form for maintenance work.

Intelligent Infrastructure Management

From job planning through producing as-built drawings all the way to operation monitoring: RIB's infrastructure management software solution supported the construction engineers of the Klebl company in all phases of the project to build the new Hardhöhe station on the Fürth underground line (near Nuremberg in Germany), with adjoining tunnel sections on both sides using the cut-and-cover technique.

Based in Neumarkt in the Upper Palatinate region of Germany, the Klebl Group is known for its successful handling of all types of construction projects including factories, sports complexes, healthcare, security and administration facilities. Formerly a family firm, Klebl is now a leading player in the construction and building materials sector, and has always represented a combination of tradition and innovation. Besides the classic execution of medium and large-scale construction projects, the Klebl Group realizes turnkey projects as general contractor. Its core competences also embrace infrastructure improvement and a trade centre and innovative business park in Neumarkt.

Forging links

The construction of underground railway lines and roads, bridges and buildings for airports creates new links for more mobility. This was also the case with the Fürth underground in the middle of the suburb Hardhöhe. The consortium Klebl - Bauer built a cut-and-cover 440 meter long construction in Fürth in three phases. Carcassing, commissioned by infra fürth verkehr gmbh, was completed in December 2006.

Within the 440 meter construction zone, a station of about 90 meters in length and two areas of switches were built - in the immediate vicinity of houses and apartment blocks. Deformation monitoring was a compulsory task throughout the entire construction phase. In addition, Klebl built a link to the already existing tunnel. The project entailed moving 32,000 cubic meters of soil - the building pit was twelve meters deep. One to two Klebl teams led by construction engineer Bernhard Müller were on the construction site every day as well as in the office. During the non-stop building site operations, the experts of the Neumarkt construction company had to cope with poor light conditions, noise and dirt. Their top priority was to ensure maximum precision, outperforming the already extremely high specifications of infra fürth.

Challenging surveying work

"There's no such word as can't. "This was the motto of Bernhard Müller and the Klebl team: Using the software solution for infrastructure projects from the RIB company, the experts from Neumarkt were able to reliably monitor and check all the surveying phases. "RIB's STRATIS software supported our project from start to finish," declares Müller, a qualified engineer. "Whether for importing external data from the structural engineers, calculating the mass-spring elements (MSE) using the STRATIS 3D Model Design, fitting digital design data on the basis of unambiguous coordinates, so-called block joint points or passing all the geometric data from the software to the S6 Trimble tachymeter.

"From the ten surveying points of the basic network, the Klebl team compressed the observation grid around and within the existing tunnel construction. One of the engineers' first jobs was to ensure that the rescue and emergency access routes were effective and to remodel the situation. To secure the tunnel profile, the original decision to build a bored or soldier pile wall was scrapped in favor of an MIP wall* with a level surface. The condition was determined by surveying and the wall thickness was measured. The existing wall was then beveled at critical points. With these comparisons of specified and actual values, the Klebl company was able to guarantee the specified minimum wall thickness.

"The plans given us by the client were in dxf and dwg format. The RIB software enabled us to fit them via the block joint points using Helmert transformations without any great effort," the qualified engineer reports.

Maximum precision was their top priority. With the STRATIS® 3D Model Design the engineers calculated the mass-spring elements (MSE).

Millimeter precision

With the MSE system, the rails are fastened onto a solid concrete trackbed resting on elastomeric bearings at regular intervals. Separated by an air slit, these elements prevent noise being transferred to adjacent buildings. The slabs are cemented to a separating layer on the tunnel floor, then raised with hydraulic presses and mounted onto the spring bearings.

"It was only possible to perform the underground construction work so close to a residential area by applying a method like this", says Müller. The main challenge for the team was to guarantee that the trains ran particularly quietly. To achieve this, tracks have to be laid with millimeter precision. The actual position of the concrete surface may not deviate from the specified position by more than +/-5 mm within the track axis. The Klebl engineers demonstrate this by control measurements and a level of reference in a grid of 2.50 m or 1.25 m in radial areas. The coordinates and plans in the Gauss-Krüger system in a grid of 2.50 therefore demanded complex recalculation. Data transfer was no problem for the project teams with the 3D Model Design of the RIB software solution.

Using an S6 Trimble tachymeter, the engineers from Neumarkt staked out the position and height of the backfill concrete points. Geometric alignment data from RIB STRATIS can be quickly and easily input into the tachymeter and then further processed on-site with special software solutions.

"We did excellent work," Bernhard Müller sums up. "As far as accuracy is concerned, we even outperformed the specifications in the end. In every phase of the project we could rely on the support of the RIB software." The project plans of Klebl are now available to the operators of the underground railway in digital form for maintenance work.

Mixed-in-Place technique: Alternative to bored pile walls

Industries>Infrastructure>Rail Infrastructure>Klebl

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