Since the sixties, the A48 „Eifelautobahn“ has been linking Koblenz in the valley of the Rhine with the cities of Trier and Saarbrücken situated further to the south-west. Meanwhile the 22cm concrete pavement shows severe heaving and other signs of damage to such an extent that it requires total rehabilitation.

The first section to undergo rehabilitation was the 6.3km stretch between the access points of Kaifenheim and Kaisersesch. The 2-lane carriageway including hard shoulder has a width of 11.5m. Based on a traffic load corresponding to 34 x 106 passes of 10 ton vehicles expected for the 30 years to come, construction companies were invited to bid for a contract specifying the building of a new asphalt pavement on top of the existing concrete. This method of rehabilitation proved possible due to the fact that, from the geological point of view, the ground under the old concrete pavement is not likely to settle any more. An asphalt package totalling some 28cm in thickness was to be laid on the shattered concrete pavement. When tenders were invited, Motorway Authorities of Montabaur, a branch of the Federal Roads and Traffic Authorities of Rheinland-Pfalz, specified paving of the bituminous layers in two parallel strips „hot to hot“.

German contractor Gebrüder von der Wettern offered a remarkable alternative, in fact the paving of all bituminous layers in full-road width. For this project Peter Böhm, a company executive, relied on the performance of a strong team: the SUPER 2500 with SB 300 Fixed-Width Screed in TP1 version and the MT 1000-1 Mobile Feeder, two machines of German manufacturer VÖGELE based at Mannheim. The tracked SUPER 2500, a heavy-duty machine, is capable of paving asphalt in widths of up to 16m. When it comes to paving this large widths, the paver’s combination with a MT 1000-1 Mobile Feeder enhances substantially both daily lay-down rates and the quality of the pavement being laid. Thanks to the Mobile Feeder, feed lorries hauling the mix are no longer tied to the paver which allows non-stop paving.

Scrutiny of the method offered as an alternative revealed not just one but a number of advantages, so that Gebrüder von der Wettern won the contract for road rehabilitation in full-road width with the VÖGELE machines. The use of this modern method on the A48 was a première in Rheinland-Pfalz. It was the first time that the entirety of asphalt layers for a carriageway this wide has been paved without joints.

What are the outstanding advantages that construction in full-road width by a paver and a feeder offers?

1. Longer In-Service Life of the Road, Less Repairs

An investigation into pavement damage normally manifesting itself in a road’s wearing course after an in-service life of 10 – 15 years showed that weak points are above all those places where joints exist in the lower layers. A pavement built in full-road width, in contrast, stands out through a considerably longer in-service life. Frost heaving is avoided right through the entire asphalt package as there are no joints allowing water to seep down. This reduces substantially the amount of pavement damage and saves cost for repairs.

2. Shorter Construction Period

The high daily lay-down rates achieved by the paving train result in a far shorter construction period. For the present contract completion had been scheduled in a 90 working days‘ deadline. Thanks to paving in full-road width, construction was almost 25% quicker equalling savings of 20 working days. A circumstance especially important on this project, as during construction only one lane in either direction was available to traffic. Tailbacks at the bottlenecks as a result of a high traffic volume and danger of accident in the area of the building site could, thanks to the shorter time needed for road rehabilitation, be reduced to a minimum.

3. Enhanced Travelling Comfort

A road without a joint enhances the car drivers‘ travelling comfort. Beyond that NIVELTRONIC, the Automated Grade and Slope Control System developed by VÖGELE and installed in the SUPER 2500 paver, provides for an excellent surface accuracy and truth to line and level. Irregularities in a transverse direction, too, are avoided thanks to the Mobile Feeder, enabling the paver to pave at a constant speed. No stops occur by lack of hot mix and no shocks are caused by feed vehicles docking at the paver.

4. Fewer Staff Required for Paving

Besides the paver operator, no more than 2 to 3 staff to operate the screed are needed to do the paving job. For the Mobile Feeder even one man will do. All in all, the crew needed around the paver is smaller compared with „hot to hot“ paving, and they complete their job in a shorter period of time.

In order to ensure that paver and Mobile Feeder can work efficiently and economically, it is a must that hot mix of constant quality is supplied to the job site in sufficient amounts during the whole period of road rehabilitation. This requires excellent preparatory work for the job and professional logistics, given the impressive average of 4,600 tonnes of hot mix paved per day by the two large machines.

There was a close co-operation with the operators of the asphalt preparation plants. The hot mix supplied by up to four mixing plants was hauled to the building site by 24 feed trucks, all of them 28 ton vehicles. For the base course some 16.5cm thick, laid as a level regulating course on the shattered concrete pavement, the trucks supplied 33,000 tonnes of mix (grain size 0/32) in only 8 days. The base course was paved at a speed of 2 m/min. Paving the 8.5cm thick binder course (grain size 0/16 S) was completed in just 3 days. Here the pave speed was 4m/min. It also took no more than 3 days to place stone mastic asphalt (SMA 0/8 S), 3cm thick, for wearing course at a speed of 2m/min.

For monitoring the quality of the pavement under construction, a laboratory for the testing of building materials had been engaged to constantly measure density and layer thickness and take samples of the materials used. Already before the contract was completed it was quite evident that contractor Gebrüder von der Wettern and the VÖGELE machines had met all the requirements. Measurements proved that the paver’s SB 300 Fixed-Width Screed in TP1 version had produced a density of up to 85%. And measurements of the binder course’s evenness carried out by the Motorway Authorities showed that deviations from specified values were under 3mm. Thus the quality of evenness reached for the binder course was as high as the one specified for wearing course. For the wearing course, values of similar excellence are expected.

In order to be on the safe side, service technicians of the machines‘ manufacturer VÖGELE and of WIRTGEN Windhagen Vertriebs- und Service GmbH were standing by during the whole period of construction. „Our specialists were ready to travel to the building site at any time should problems occur“ says Klaus von der Gathen, managing director of WIRTGEN Windhagen GmbH and is satisfied: „Their intervention, however, was not necessary as the two large machines operated impeccably throughout the contract“.

The advantages that paving in full-road width offer on the one hand and the reports on the excellent progression of works on the other were good reason for Horst Oltersdorf, head of the Federal Roads and Traffic Authorities of Rheinland-Pfalz, to visit the building site. He was impressed, indeed, by the high pavement quality and all aspects of the complex project were discussed from various angles together with Uwe Schminke of the Motorway Authorities Montabaur, Peter Böhm of contractor Gebrüder von der Wettern, a member of the VÖGELE board of directors as well as representatives of the hot mix suppliers and the testing laboratory.

On that occasion Peter Böhm said: „Thorough preparations have been made before starting work in order to be sure that rehabilitation method, machinery and building materials are perfectly selected to match the job and potential risks are precluded from the very beginning.“ The preparatory work included discussion with the mixing plant operators, trials with various mixes paved on test sections and instruction of the paving crew by VÖGELE and WIRTGEN Windhagen. Uwe Schminke of the Motorway Authorities Montabaur comments on the fast progression of the job: „A large-scale project like this has never before been completed so quickly. A pavement quality at the highest level has been produced so that, in the long run, substantial savings of funds for road maintenance can be expected.“

When a final report will be in hand with results of the extensive tests confirming in black and white the positive impression gained on the occasion of the visit on site, the placing of pavement layers in full road width as an economical method for high-quality road building or road rehabilitation will, no doubt, become the usual practice in Rheinland-Pfalz.

For further information please contact:

JOSEPH VÖGELE AG

Roland Schug

Neckarauer Strasse 168 - 228

68146 Mannheim

Germany

Telephone: +49 (0) 621 8105 232

Fax: +49 (0) 621 8105 469

Email: Roland.Schug@voegele-ag.de

www.voegele-ag.de