“Building Compact Asphalt Pavements Works Excellently with InLine Pave®”
Interview with Jürgen Israel of Bautzen Roads Authority, Germany, about InLine Pave®.
Numerous state authorities for roads in the east and west of Germany welcome the method of building compact asphalt pavements with two pavers. Within the states’ responsibility for state roads, the InLine Pave® technique has been officially accepted and approved by decree in the states of Brandenburg, Saxony, Saxony Anhalt, Mecklenburg-Western Pomerania and Saarland. RoadNews spoke with Jürgen Israel of Bautzen Roads Authority about his experience with InLine Pave® and construction of the B 178 (n) Federal highway near Löbau.
RoadNews: Mr Israel, you are Head of the Department for Road Construction as part of Bautzen Roads Authority. What does the term “quality” mean to you and how do you evaluate the quality of the “hot on hot” paving technique?
Jürgen Israel: Quality is of immense importance to us. After all, we are responsible for 1,600km of state and Federal highways. Our scope of responsibility includes not only road maintenance, but also extension and new construction of roads. No matter, however, whether it is new construction or pavement rehabilitation, we have to make responsible use of the taxpayers’ money. This is why we are looking for paving methods capable of prolonging the lifespan of roads.
RoadNews: Does heavy goods traffic between east and west play a role in this context?
Jürgen Israel: Of course. And the B 178 (n) highway near Löbau requires special mention in this respect, as it represents an essential traffic link between the Czech Republic, Poland and Germany. We expect a very high volume of traffic on this Federal highway in the future, especially in terms of heavy goods vehicles. That’s why it is indispensable for the road to be built in such a way that it can cope with high traffic loads without requiring rehabilitation after just a short time. This is why we included, from the start, “compact asphalt pavements” into our considerations.
RoadNews: Why “compact asphalt pavements” and where do you see the key advantages?
Jürgen Israel: It’s very simple, really. Being able to pave binder and surface courses in a single pass to create a homogeneous asphalt package, 12cm thick, offers lots of advantages. In a compact asphalt pavement, you do not have any separation of layers and “hot on hot” paving yields an excellent interlocking of layers. And this is what matters most to us, as according to our experience, a poor bond of layers is one of the major reasons for pavement damage.
RoadNews: So quality was a top priority when building the B 178 (n)?
Jürgen Israel: Absolutely. Although we only can get quality as a claim accepted if the paving method also meets economic requirements. But we had no conflict of interests at all on this section of the B 178 (n). In order to ensure fair competition, we did not make any restrictions in terms of technology and did not confine bids to “compact asphalt pavements” alone, but also permitted alternative offers based on conventional paving. In the end it was compact pavement construction using two pavers which won the day.
RoadNews: Have there been any special challenges on that job site?
Jürgen Israel: Well, in this context mention should be made of the 8 bridges that are located on the 5.9km stretch. On 6 bridge decks, the task was not to pave binder course and surface course, but to pave just 4cm surface course onto the existing mastic asphalt. What’s more, two of the large bridges were not allowed to be accessed at all by the pavers, as construction work had not yet been completed. You see, there were some tricky problems that had to be solved.
RoadNews: And how were these problems solved?
Jürgen Israel: The contract was awarded to Strabag which had offered InLine Pave® as a building method. This method allows surface course and binder course to be paved independently of each other, as it is possible to uncouple the InLine Pave® train at any time. In other words, the 4cm surface course could be paved on the bridge decks without interrupting the overall process. And thanks to the mobility of the uncoupled single machines, it was also possible for them to by-pass the bridges by travelling down the embankment on temporary ramps or site roads under their own power.
RoadNews: Mr Israel, as you have gained experience with this method, what do you think are the advantages?
Jürgen Israel: In addition to the advantage of a strong bond of layers, which is undeniable, this technique yields a high degree of evenness – a quality feature that every motorist welcomes. Once the InLine Pave® technique had been explained to us in detail, it quickly became clear that evenness can be obtained best by the self-levelling properties of two separate pavers working one behind the other. Of course, we also discussed the matter beforehand with colleagues from other divisions, who had experience of all paving methods available. And the clear conclusion was that with InLine Pave®, we could expect a very high standard of quality in terms of evenness.
RoadNews: What were the results of your final tests?
Jürgen Israel: These tests confirmed our expectations. The evenness on the B 178 (n) is superb. Indeed, our expectations have been more than fulfilled.
RoadNews: When colleagues from other Roads Authorities seek your personal advice for inviting tenders, what is your recommendation based on your experience?
Jürgen Israel: Well, first of all, if you’re convinced of the merits of “hot on hot” paving, then you should invite tenders for it where it makes sense from both the economic and technical points of view. Secondly: tenders should be invited in competition with “conventional paving” by stating explicitly that alternative offers for “compact pavement construction” are welcome. Or thirdly: you invite tenders for “compact pavement construction” and admit alternative offers for “conventional paving”. This fulfils all requirements of a fair competition.
RoadNews: Would you recommend “trial job sites” for the InLine Pave® technique?
Jürgen Israel: No. Trial job sites and extensive reports in their wake are no longer necessary for InLine Pave®. However, prior to commencing work, the contracting authority should make sure that the company carrying out the roadworks has a good strategy for “mix supply logistics”. Building compact asphalt pavements works perfectly with InLine Pave®. Whether evenness, degree of compaction, layer thickness or bond of layers – on the B 178 (n) near Löbau there was nothing to complain about. For us, the results of InLine Pave® were absolutely convincing!
RoadNews: Mr Israel, thank you for taking your time.