Construction projects designed to be completed in an extremely short time are demanding in many respects. In densely populated areas, particularly, the requirement for road rehabilitation to be completed rapidly is becoming more and more urgent, as job sites on busy major roads cause traffic jams. They require precise planning, a high degree of process reliability and reliable machinery. They also demand experience and competence from users and experts. All these parameters were important for rehabilitating a 3.6 km section of the A3 motorway near Duisburg. As this busy commuter route carries some 120,000 vehicles on weekdays, the highways authority, Straßen.NRW, decided to carry out the rehabilitation project by closing the road completely.
The works started with a full road closure in both directions. After that, the right hand carriageway, which is made of concrete and did not require rehabilitation, was separated from the adjacent asphalt lane using a side milling wheel. Four WIRTGEN cold milling machines - W 210i, W 220i and W 250i - started removing the surface and binder courses which required rehabilitation. About 20 hours were scheduled for this part of the work, and the asphalt paving started before milling work was even complete. Paving had to be complete to allow enough time for follow-up tasks such as the application of road markings. The route was set to be opened to traffic to enable commuter traffic to start the week normally.
Six VÖGELE pavers in service simultaneously
A window of just 27 hours was available to pave an area of 60,000 m2. The contractor’s team met this challenge with six VÖGELE pavers. Two SUPER 2100-3i machines first paved the binder course. One of the two Highway Class pavers worked in one direction of travel whilst the other paver simultaneously started at the other end of the job site, working in the opposite direction. The surface course consisting of low-noise stone mastic asphalt (LOA) was then paved by two SUPER 1800-3i SprayJet machines using the “hot to hot” method.
Three mixing plants were commissioned with production of the asphalt to guarantee material supply on this tight schedule, with a further plant in reserve in case needed. 130 trucks made 500 trips to transport the hot asphalt to the job site between the junctions at Duisburg-Kaiserberg and Breitscheid. In all, 16,000 t asphalt (12,000 t for the binder course and 4,000 t for the surface course) had to be produced, transported and paved.
VÖGELE material feeder ensures a continuous supply of mix
Two VÖGELE PowerFeeders of the MT 3000-2i Offset type accepted the mix from the trucks to guarantee a continuous supply to the pavers. Use of two feeders was es-sential on this time-critical project: as the material feeder operators were coordinating unloading, this allowed the paver operators to give their full attention to the paving process. Given a whole 500 truckloads in a few hours and the high pave speeds, this was essential.
Spraying on emulsion and paving asphalt in just one operation
The VÖGELE SUPER 1800-3i SprayJet spray pavers also ensured an efficient process: they sprayed on the bitumen emulsion and paved the asphalt surface course in just one operation. In addition to saving time, paving the A3 with VÖGELE SprayJet technology had other benefits: as the freshly-applied film of emulsion was paved over immediately following application, construction vehicles were unable to drive over the binder film and damage it. This improves interlocking and thus also the service life of the road.
Road opened to traffic; objective achieved
The smooth interaction of the team and the machine technology from WIRTGEN and VÖGELE meant that finally, the A3 motorway reopened to traffic. “That was an incredible performance by the whole team. Everyone supported everyone,” said construction manager Niklas Lehmann after the project was complete.