VÖGELE Paver Provides for Perfect Evenness

SUPER 1800-2 with NAVITRONIC Plus® builds vehicle testing area

Test drivers and vehicle developers will soon be able to make tyres scream when they test new vehicle components to the limit at the “Aldenhoven Vehicle Testing Centre” near Aachen, Germany. When building the new vehicle dynamics test area covering some 38,000m², the contract letting institution’s demands were highest evenness of the pavement, uniform compaction and first-class surface properties. German contractor Wurzel Bau GmbH was able to live up to these demands when they opted to use machines from VÖGELE and HAMM for this unusual “road” construction project. For building the circular area, a SUPER 1800-2 with AB 500-2 Extending Screed in TP1 version was on the scene and for final compaction several rollers from HAMM.

The paving team made sure that each total station was focused on the right prism.

The vehicle dynamics test area at the “Aldenhoven Testing Centre” of Rhenish-Westphalian Technical University (RWTH) Aachen was constructed on the site of a former lignite mine. From a road construction viewpoint, the job was real treat: several of the university’s institutes will be conducting tests on the pad measuring 210m in diameter with the aim of improving vehicle and driving safety. For example, researchers will be testing advanced driver assistance systems which automatically control the braking or steering of vehicles in the event of driver inattention. “We can’t possibly test systems like this on public roads, of course. And that’s why we need a test area like the one in Aldenhoven,” explained Prof Stefan Gies, Head of the Institute for Motor Vehicles at RWTH.

Client makes high demands on precision

An even, homogeneous asphalt surface with properties remaining stable over the course of years is crucial to obtain test results for scientific exploitation. The invitation to tender, therefore, stated: “A very high standard of quality is required for the test area and paving must carried out with great precision.”

Highest quality for 38,000m²

Site Manager Manfred Backus.

On the pad of the vehicle dynamics test area and the neighbouring approach track, the three-layer pavement of asphaltic concrete was to be built according to the highest standards in terms of evenness. On the job site in Aldenhoven, the material type AC 22 TS was used for asphalt base, AC 16 BS for binder course and AC 11 DS for surface course. A minimal slope of 1% was also required, so than rainwater can drain off. These parameters defined the requirements for the job to be carried out by contractor Wurzel Bau from Jülich. For asphalt paving, Wurzel Bau picked a tracked SUPER 1800-2 with AB 500-2 Extending Screed in TP1 version, combined with a VÖGELE MT 1000-1 Mobile Feeder for continuous material supply. Paving was carried out in 40 strips with the longest, running across the pad’s centre, paved first. Then the increasingly shorter strips to the left and right were added.

NAVITRONIC Plus® meets high requirements in terms of quality

In order to meet the high demands made on evenness, contractor Wurzel Bau relied on NAVITRONIC Plus®, the VÖGELE System for 3D Machine Control. This system not only carries out grade and slope control, regulating the layer thickness and transverse slope, but also controls fully automatically the screed’s position and the paver’s direction of motion. NAVITRONIC Plus® thus is a true 3D system of a kind solely offered by VÖGELE. The paver’s current position is picked up continuously by a laser-based total station or GPS. NAVITRONIC Plus® evaluates collected information, compares it with the route’s design data entered into the system and guides the SUPER paver precisely and fully automatically to the specified road profile. In Aldenhoven, contractor Wurzel Bau used two total stations with automatic target tracking capability. Once set up, the surveying systems tracked the paver without any help from the operating team and transmitted their results by radio to the paver’s on-board computer.

Text-book evenness

The VÖGELE paver already placed base course with high precision: the results were 5mm below the tolerance limits of ± 8mm.

Thanks to NAVITRONIC Plus®, the paving team from Jülich were able to far exceed the requirements on pavement evenness. Over a distance of 4m, the maximum tolerance limits were ± 8mm for base course, ± 5mm for binder course and ± 3mm for surface course. The very first measurements taken when paving base course revealed that the SUPER 1800-2 with NAVITRONIC Plus® was going to meet all demands with aplomb: the values measured on the lowest 8cm asphalt base deviated from the specified evenness by less than a mere 4mm. And when paving 5cm binder course and 3cm surface course, Wurzel Bau was able to even improve this result.

SUPER helper: the MT 1000-1 Mobile Feeder

In order not to drop below the minimum temperature of 135 °C for paving, the loads of the feed lorries were checked.

In addition to evenness and correct location, continuous paving of the asphaltic concrete was an important aspect, too, on this job site. This is why a VÖGELE MT 1000-1 Mobile Feeder was on the scene for non-stop supply of the SUPER 1800-2 with mix. The feeder travels ahead of the paver and is loaded from feed lorries. Non-contacting sensor technology provides that a constant distance between feeder and paver is maintained. The feeder’s task is to transfer mix, via belt conveyor, into the paver’s material hopper as required. It thus helps avoid paver stops, allowing the paver to work to capacity. This boosts flexibility during paving and prolongs the time available for lorry changes.

High compaction with VÖGELE screed meets requirements on density

Vögele paver with NAVITRONIC Plus®

Those responsible for construction of the testing area at RWTH Aachen also required a high and uniform pavement density of at least 88 – 92%. And for each strip, the precompaction was not permitted to vary by more than 2% across the full pave width. To meet this target, contractor Wurzel Bau combined the paver with an AB 500-2 Extending Screed in TP1 version equipped with 1 pressure bar for high compaction. The pave width came to 5m. “Thanks to the high compaction system, we achieved a precompaction of more than 90% across the full width,” said Senior Site Manager Peter Schiefer, who was very satisfied with the result. While a HAMM 3520 vibratory roller was on site for the earthworks, the paving team used DV rollers with oscillation, also from HAMM, for final compaction of the asphalt layers.