Modular Machine Design Plays out its Strengths
New construction of a highway with the VÖGELE InLine Pave® train.
New construction of the B 178 (n) Federal highway near Löbau in the German Free State of Saxony was extraordinary in many respects. When it came to paving the 5.9km stretch of the highway, hot on hot, the VÖGELE InLine Pave® train displayed all its advantages and completed the job quickly and highly economically.
When constructing the B 178 (n) Federal highway near Löbau, the focus was on a high standard of pavement quality, in particular for the asphalt surface course, and a high cost-efficiency. To ensure fair competition, Bautzen Roads Authority letting the contract refrained from making restrictions in terms of technology by confining bids to “compact pavement construction”. Alternative offers for “conventional paving” were admitted as well. In the end, it was InLine Pave®, the technique using two pavers, that won the contract. Particularly high demands were made on the overall quality of the road, as the B 178 (n) will link the A 4 motorway to Poland and the Czech Republic in the Zittau region. A high traffic load is expected with a high share of heavy goods vehicles.
Surfacing 6 bridge decks and by-passing 2 bridges
The 5.9km stretch of the Federal highway included 8 bridges. 6 bridge decks required paving of 4cm surface course on the existing mastic asphalt. Two other large bridges could not be accessed at all by the pavers, as construction work had not yet been completed. On the sections between the bridges, the task was to place binder and surface courses featuring perfect bonding and interlocking of layers. The paving team of contractor Strabag AG, Direktion Straßenbau Sachsen, faced up to those challenges with their InLine Pave® train.The paving train was made up of a MT 1000-1 Mobile Feeder, a SUPER 2100-2 IP for paving binder course and a SUPER 1600-2 for placing surface course. “A crucial factor when using this technology is an optimal rhythm as far as supply of the pavers with mix is concerned. If this works, then the costs of paving can be cut massively from the very first metre,” says a representative of contractor Strabag.
The VÖGELE concept for “hot on hot” paving
VÖGELE developed the InLine Pave® train especially for the innovative “hot on hot” paving technique to build “compact asphalt pavements”. InLine Pave®, however, is equally suited to carrying out conventional paving jobs to a high standard of quality and very economically. With InLine Pave®, binder course and surface course are placed in a single pass. This yields not only a perfect bond of layers but also intense interlocking. Both are basic requirements for the longevity of roads.
Machinery of standard design for high productive utilization
InLine Pave® is based on machines of series production that undergo just slight modification for the “hot on hot” paving process. For construction contractors, this means that every single machine of the InLine Pave® train can also be used for conventional paving jobs at any time. This increases substantially both the productive utilization of the contractor’s equipment pool and his return on investment (ROI). It also makes the InLine Pave® technology a highly attractive option for medium-sized construction companies.
Paving just surface course on the bridge decks
Back to the job site: surfacing the bridge decks was a tricky job. At least it appeared so at first glance. At second glance, however, the InLine Pave® technology demonstrated an unique advantage: its modularity. The machine design allows the MT 1000-1 Mobile Feeder and the SUPER 2100-2 IP paver for placing binder course to be uncoupled from the InLine Pave® train. On the 6 bridges of the highway where just surface course was to be placed, the SUPER 1600-2 alone paved the surfacing in the specified thickness of 4cm, in the conventional manner. And on the B 178 (n) job site, it was only due to this possibility that the bridge decks could be surfaced at all. Thanks to the smart VÖGELE concept, there was no interruption in the overall process. After the bridges, the 3 machines resumed work in a team and continued paving “hot on hot”. Finally, the InLine Pave® concept showed off one more advantage over large special machinery: for carrying out secondary work on the highway such as surfacing approach and exit lanes, the right single machine was always available, without a need for further machinery moving onto the job site. This boosted considerably the contractor’s flexibility in action.
88,500m² of area paved with asphalt
Most of the roadwork between the bridges was mere routine for the paving team. Though the Löbau job was the first occasion for contractor Strabag’s crew to work with the InLine Pave® train, they quickly got to grips with the equipment. This is due mainly to the fact that the paving train is made up of VÖGELE machines from series production, which have undergone just slight modification. The ErgoPlus® operating concept is an important aspect in this respect. Paver operators are quickly familiar with their ErgoPlus® consoles on which paver functions are arranged in logical groups. Once familiar with the system, users can operate all other pavers of the “dash 2” generation without extra training. The team working “hot on hot” on the B 178 (n) Federal highway also benefited from this advantage. They placed 10cm binder course and 2cm surface course without any problem. In both highway directions, they worked in 7.5m width. All told, asphalt was paved on an area of some 88,500 m².
Perfect evenness achieved
The InLine Pave® concept stands for maximum evenness of the final pavement. The use of two pavers, operating separately and each equipped with a floating screed, helps perfectly level out irregularities. And InLine Pave® does not make special demands on the evenness of the road base. A tolerance up to 10mm, usually specified for base course, is absolutely sufficient for InLine Pave® to achieve a final surface of highest accuracy. On the Löbau contract, the paving team worked with NIVELTRONIC Plus®, the System for Automated Grade and Slope Control, combined with a modern sensor system from VÖGELE. The paver placing binder course came with a Big MultiPlex Ski to scan the base, which served as a reference for grade and slope control. The system offers the particular advantage that even long irregularities, such as undulations, can be reliably levelled out. It is the combination of the paver’s self-levelling property and the Big MultiPlex Ski that has achieved superb results: the contracting authority was fully satisfied with the pavement’s quality.
“Compaction with oscillating rollers is optimal”
Immediately behind the paving train, two HAMM DV 90 rollers with oscillation followed to produce the final density of the new asphalt pavement. For InLine Pave® asphalt packages, the superiority of compaction with oscillating rollers is primarily due to the relative thicknesses of the two layers. In conventional asphalt paving, the thicknesses of binder course and surface course are 8cm and 4cm while, when placing two layers “hot on hot”, binder and surface course thicknesses are 10cm and 2cm. “The load exerted by vibratory compaction is so great that the thin surfacing might risk to be displaced,” explains Gerd Lenz, Applications Consultant of HAMM. “The situation is similar to thin overlays, which also can only be compacted with oscillation or in static mode.” Using HAMM oscillating rollers avoids this risk. The pavement is compacted dynamically and quickly, achieving a perfect surface finish and an excellent initial grip. This also was the result on the Löbau job: the DV 90 VO roller with oscillation had produced the specified density after just three passes. The DV 90 VV vibrating roller operated in static mode.
Job Site Details
New construction of a “compact asphalt pavement” on the B 178 (n) Federal highway near Löbau, Germany
Length of section: 2 x 5.9km
Total area paved: 88,500m²
Pave width: 2 x 7.5m
Layer thickness: binder course 10cm, surface course 2cm
Binder course: asphaltic binder (Abi 0/22 S) with binder (PmB 45 A)
Surface course: stone mastic asphalt
(SMA 0/8 S) with binder (PmB 45 A)
VÖGELE InLine Pave® train comprising:
MT 1000-1 Mobile Feeder
SUPER 2100-2 IP for binder course with AB 600-2 IP Extending Screed
SUPER 1600-2 for surface course with AB 600-2 TV Extending Screed
HAMM DV 90 VO and DV 90 VV Rollers