Maximum performance for the Albvorland Tunnel

Germany | High speed section Stuttgart-Ulm

Five HGT layers, great demands for the evenness and the logistic challenges: The paving of a fixed road in two 5 miles (8 km) long tunnel tubes of the Stuttgart-Ulm of Deutsche Bahn was challenging. The paving team addressed this challenge using the SUPER 2100-3i including the AB 600 TP2 high compaction screed and the 3D control system. One MT 3000-2i Offset material feeder supported the job site logistics.

Challenging paving in the railway tunnel with a length of 5.1 miles (8.2. km).

Road construction projects in railway tunnels are especially challenging. On one hand, the tight job site situation requires accurately coordinated logistics. One the other hand, the requirements for the track bed are enormous: High speed sections must be absolutely level and must be able to withstand extreme loads. Because the Deutsche Bahn trains travel faster and faster, they are longer and they travel at higher frequencies.

It was intended to install a fixed road in the Albvorland Tunnel with a length of 6.1 miles (8,176 m), a road section of the Stuttgart-Ulm of Deutsche Bahn designed for a speed of 156 miles/h (250 km/h). Fixed roads consists normally of a frost protection layer, a water-bound base course (HGT) and a concrete or asphalt course. Compared to crushed stone beds they can absorb significantly more loads, they are durable and almost free of maintenance.

Roller compacted concrete follows after five HGT layers.

The requirements for the build-up were even higher than normal for the Albvorland Tunnel: The Kurt Gansloser GmbH, the executing construction company assigned by the construction service provider Implenia Construction GmbH Munich was assigned to install five HGT layers with a thickness of 10 inches (25 cm) each and a roller compacted concrete layer of 5 inches (12 cm) in two single track tunnel tubes and in an additional proximately 1.9 miles (3 km) long section. The working width was 21.3 ft (6.50 m). The tunnel floor needed to be increased to the required level and an especially low settling foundation for railroad ties and tracks had to be established. At the same time, Deutsche Bahn ensured that damage to the underlying wires did not occur due to the railway operation.

SUPER 2100-3i: Optimal for tunnel pavings

“Close coordination is required for these type of measures. A precise planning, a fit team and powerful machines are absolutely required”, says Christopher Gansloser, Managing Director of Kurt Gansloser GmbH. “The subject of emissions plays of course an important role especially for tunnel job sites.” The specialist of roads and underground construction therefore uses the SUPER 2100-3i larger paver made by Vögele. The Highway Class machine has a paving capacity of 1,100 t/h and - based on its state of the art drive concept - it is especially qualified for tunnel pavings. The engine is equipped with a multi-stage exhaust gas after treatment system and therefore fulfills the strict guidelines of the European exhaust emissions standard V. The intelligent engine management and the so-called EcoPlus also reduce the fuel consumption and the emissions additionally by up to 25%.

In addition, the simple control and clear arrangement made the SUPER 2100-3i very attractive. The drivers and the operators had a good view on all relevant machine and job site areas despite the tight conditions and the sparse tunnel lighting. Because on one hand, the ErgoPlus 3 operating consoles are glare-free backlit. And on the other hand, LED headlamps in the machine roof, additional light balloons and LED spots in the screed control consoles provide a large area illumination of the entire work space.

High-compaction technology improves the paving quality

To achieve a high quality paving, the Kurt Gansloser GmbH prefers the AB 600 extending screed. The screed can be extended hydraulically to up to 19.7 ft (6.00 m) and it was extended using widenings to the width of 21.3 ft (6.5) m as required by the width in the tunnel tube. To achieve the highest precompaction for all five layers, the team used the TP2 variant of AB 600 with tamper bar and two pressure bars. The pulsed hydraulic controlled Vögele pressure bars are unique on the market and they permit precompaction values of up to 98%. This is the reason why the paving team was able to guarantee a high paving quality and efficiency across all layers and why the team was able to save time during the subsequent rolling passes using the HD 10 VT and HD 13i VV tandem rollers from Hamm.

High evenness requirements

The quality standard for the track bed also required a height and slope control of the fixed-width screed accurate to the millimeter. The tolerance range for the absolute position of the 4.7 inches (12 cm) thick roller compacted concrete layer was only 0.4 inches (± 10 mm). To ensure that the accuracy is exactly observed, the construction company used the non-contacting Navitronic Basic 3D control for the paving of the HGT layers. The Vögele system offers an open interface that can be used to connect positioning systems of a variety of manufacturers.

The Kurt Gansloser GmbH utilizes the Trimble control system. The position and the location of the screed were measured and deviations were calculated. The interface transmitted them to the Vögele Niveltronic Plus system for automated grade and slope control, which controlled them. The team used the Vögele Big-MultiPlex-Ski sensor system for the roller compacted concrete layer to level last undulations. “This allowed us to observe the tolerances without problems and we are very satisfied with the result”, said Gansloser.

Complex logistics, efficient material feeder.

The mix delivery represented a special challenge: Twelve trucks with approximately 20 t of material each had to enter the tunnel daily. They had to travel backwards through the tunnel tube to hand over the mix. Extensive technical construction works were performed at the tunnel in parallel, and this made the logistics even more difficult. “These were partially difficult circumstances that forced us to first adjust to this environment”, said Gansloser. “But after a short while, we were able to pave almost without interruption.” This was on one hand due to the short distances to the mixing plant at the site and on the other hand it was due to the Vögele MT 3000-2i Offset material feeder. The PowerFeeder material feeder has a conveying capacity of up to 1,200 t/h and it provided a continuous and shock-free material transfer to the paver. “The material feeder increased the efficiency and the quality enormously and saved us a lot of time.” says Gansloser. “The construction site was ultimately on optimal interaction between client, planers, paving team and machines.”