The most important traffic hub in the Bonn district of Beuel is Konrad-Adenauer-Platz. This is where the B 56 runs through Bonn, and numerous junctions lead to busy residential and shopping streets from this square. Several underground and urban railway lines also depart from there on a shared track via the Kennedy Bridge to the Bonn districts to the left of the Rhine. However, because the underground trains have high door sills whereas the urban trains have low floors, passengers have always had problems getting on and off at the shared stop. In May 2000, Bonn city council passed a resolution to divide the stop, and combined this with a more pedestrian-friendly revamp of the square. The construction work got underway in January 2003. Since then, two new stops have been created, extensive drainage work carried out, wide footpaths built, state-of-the-art underground refuse collection systems installed, the track beds reconstructed and the tram rails repaired. The last major project, the rehabilitation of the pavement surface, was implemented at the end of May 2005. To do this, the entire square was shut off for a weekend with the proviso that the traffic would be able to flow through this bottleneck again on Monday morning.

To ensure that everything ran according to schedule, the contractors involved depended on high-quality, reliable road building equipment from WIRTGEN, VÖGELE and HAMM. In addition, there was the certain knowledge that even during night-time work and at the weekend, they would have been sure of expert support from WIRTGEN Windhagen Vertriebs- und Service GmbH, whose responsibilities in NRW include the WIRTGEN, VÖGELE and HAMM brands. In short, it never came to this.

Clean preliminary work with two small WIRTGEN W 50 DC Milling Machines

With the pavement surface of the B 56 having already been milled off to a uniform level some time earlier, the company GMS from nearby Merzenich mild off asphalt from all links to the numerous side-streets on an area of some 6,500m² with its two small W 50 DC milling machines. There only was a window of 8 hours to mill off and clean the 20-plus sections before handing them over to the “blacktop team”. A demanding schedule, considering that machines had to mill off asphalt also around manhole covers and other street furniture about 5cm deep. However, as the small milling machines are not only user-friendly, but also have a high-torque engine with 92 kW output, GMS performed the task with no problems in the time required.

Low-noise asphalt laying with two VÖGELE SUPER 1600-1 Pavers

After the agile small machines had milled off asphalt on the first sections, two crews of contractor Widdig from neighbouring Bornheim started work on laying fresh asphalt on the connecting roads. The mix used was Stone Mastic Asphalt (0/11 S) with PmB 45 C, a thermoplastic-modified bitumen. This material, which is extremely durable but hard to compact, was specified because the B 56 carries a lot of heavy-duty traffic.

In the early hours of Saturday morning, the two paving crews began paving the overlay on the B 56. There are two lanes to the left and two to the right of the tram lines, with a width of 7.5m. The layer thickness on the entire area was around 5cm. To keep to the tight schedule safely, Widdig used its two SUPER 1600-1 pavers. These machines have proved extremely reliable in the past and achieve a high and uniform pre-compaction at a high pave speed. In addition, the VÖGELE pavers come with a powerful 96 kW Perkins engine, whose power kicks in effectively at low engine speeds. This property, together with the engine management system, ensures reduced fuel consumption and low noise emissions, particularly in ECO Mode. This is especially important on inner-city applications, where there is increasing emphasis on using the quietest possible construction machines. In addition, low fuel consumption means cost savings for the building contractor. Last but not least, the AB 500 TV Extending Screed with infinitely variable pave width and separate height adjustment of its extending units offers the high variability that helps paving teams work on this kind of site in the city.

DV 90 OV from HAMM compacted the thin asphalt overlay with oscillation

The subsequent final compaction of the thin asphalt overlay was carried out using two HAMM DV rollers with oscillation. This means that dynamic compaction was performed here without impairing the installations below the pavement surface, the immediately adjacent houses or the track beds of the tram lines. In contrast to vibratory rollers, the HAMM oscillation system keeps the drums in constant contact with the ground, thus achieving faster compaction. Furthermore, as the oscillation system only transmits 15% of the vibrations of conventional vibratory rollers, it can be used closer to sensitive structures, across cables and underground piping systems, and even on bridges and in multi-storey car parks. In addition to improved compaction, the system also boasts lower noise levels and therefore increased ease of use. All these features were crucial to application in the Bonn district of Beuel. With the oscillation roller, the driver from Widdig compacted the mix to the required 98% in only a few passes. The alternative would have been static compaction, which would not have been possible in such a short time with only one roller per paver.

Oscillation, however, was not the only outstanding feature of the HAMM DV 90 OV, which can also be used as a vibratory roller. It is a machine from HAMM’s new DV series, which comes with a sophisticated control system and a fully glazed panoramic cabin. The ergonomic design allows the driver not only to adjust his comfortable seat to ideal settings for his height and stature, but also to move the entire cabin far beyond the width of his machine for an unobstructed view of the pavement edge. In addition, when initiating a change in direction, the driver’s seat turns through 180° automatically or at the touch of a button. The advantage: the roller operator always drives forwards. There are two major benefits related to this feature. When „driving back“ from the paver, there is no need for him to twist around in his seat, he is sitting comfortably in a healthy posture. And safety on the job site is enhanced substantially as he can see any obstacle that might be in his way at all times. After asphalt paving and compaction had been completed on Saturday earlier in the afternoon, enough time was left for cooling, so that the B 56 could be handed back to traffic on Monday morning - at 5 am precisely.

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