FGSV Colloquium // InLine Pave® Rooted in the German Catalogue of Construction Methods
Part 1: Colloquium of the German Road and Transportation Research Association (FGSV)

InLine Pave®
Rooted in the German Catalogue
of Construction Methods

Compact asphalt pavements win the day

A highly efficient method for producing two prime quality asphalt layers with two pavers in a single pass – that’s InLine Pave® from VÖGELE in a nutshell. Following a phase of intensive testing and analysis, this method was officially approved by German authorities in early 2012 for use in road construction. This prompted the German Road and Transportation Research Association (FGSV) to organize a colloquium devoted to an all-round discussion of compact asphalt pavements. RoadNews was there and has prepared the following report on this meeting of high-ranking experts.

Population density, developments in traffic and transport and Germany’s location in the heart of Europe have resulted in high traffic loads for its road network. Not only is the number of lorries increasing, their axle loads are rising, too. In addition, gross loads of 60 tonnes or more are also becoming increasingly frequent on European roads. New technologies are needed to build and service roads economically and to prepare our network of roads for tomorrow’s loads.

The InLine Pave® method developed by VÖGELE is such a technology. It stands out not only technically, but also economically and was included in the German catalogue of construction methods as a standard method in early 2012. This is rather like receiving a “knighthood”, as Rupert Schmerbeck from the Motorway Directorate in Southern Bavaria aptly described it during the FGSV colloquium.

The FGSV’s declared aim is the further development of the road and traffic system through the interaction of science, industry and administration. Interdisciplinary committees prepare the documents required for the technical rules and standards, and subsequently report on the latest developments to the trade public at such meetings as the colloquium in Kassel.

Quality boosted by compact asphalt pavements

As the various papers clearly showed, compact asphalt pavements have several technical advantages. Durability is one of the most important aspects. It results from the particularly stable bond between the binder course and the wearing course, as they are not just “glued” together, but also interlock. This ensures that shear stresses are discharged from the asphalt wearing course more effectively than with any other construction method. Through this mechanical relief, the service properties of the asphalt surfacing are preserved for a significantly longer period of time.

In his paper, Dittmar Marquordt from the road construction authority of Saxony-Anhalt, Germany, described the effect as follows: “Compact asphalt pavements mean a leap in quality: rutting is effectively eliminated.” And he should know, for the Land of Saxony-Anhalt was actively involved in the development process, inviting tenders for numerous projects and monitoring them. Well over 1,000,000m² of compact asphalt pavement have already been constructed in the region for which he is responsible.

Thinner wearing course

Compact asphalt pavements also yield advantages as regards the road structure, for the layer thickness can be modified towards thinner wearing courses. As several of the speakers explained, the funds saved here are invested in lighter road construction materials with better grip. Experience has shown that a compact asphalt pavement with a two centimetre thinner wearing course on a two centimetre thicker binder course also produces outstanding long-term results.

Dittmar Marquordt reported on a typical case: a regional road near Magdeburg, the capital of Saxony-Anhalt, which is used by many lorry drivers to bypass the A2 motorway on which they would have to pay toll fees. “Traffic is heavy on this part of the regional L 52 road. Although the asphalt was paved in critical autumn weather conditions, the voids content and degree of density are exactly as specified and the roadway has so far been able to withstand the enormous stresses without damage.” Like many other speakers, he concluded that “the concept of a modified layer thickness works”.

Successful application in all construction classes

The experts also agreed that compact asphalt pavements are cost-efficient not only on motorways and high-speed roads of the highest construction class SV, but also on most other roads. To date, combinations of binder and wearing course, as well as base and wearing course have successfully been built for roads of construction classes I – IV. The technology is currently being tested on smaller municipal roads of the lower construction classes, as well as for industrial areas. The results obtained so far are promising.

Ideal for new construction and pavement rehabilitation

Compact asphalt pavements can be used both for building new roads and for rehabilitation of existing roads. When rehabilitating “conventional” pavements, the new road design comprises a 10cm binder course under a 2cm wearing course instead of the previous 8cm binder course and 4cm wearing course. The advantages are three-fold: less of the valuable wearing course material is needed, the bond between layers and hence the load-bearing capacity are improved, and both layers are paved in a single pass, thus saving time.

Optimized job-site management

The positive experiences and numerous possible applications convinced the colloquium’s participants of the advantages of compact asphalt pavements. Friedhelm Vogt, from the Land authority for roads and transportation in Lower Saxony, was one of those convinced. He works in construction management and was already familiar with the method: “Compact asphalt pavements offer advantages both economically and in terms of construction technology. Paving proceeds more quickly, with shorter construction periods and less nuisance to traffic.” Being able to use the considerable heat potential which permits paving at lower outside temperatures is another advantage for him, as a contracting party: “It increases our flexibility without having to compromise on quality.”

Worldwide potential

Highways authorities throughout the world are interested in building strong, durable and therefore sustainable roadways. Several speakers reported that the “pioneers of compact asphalt pavements” were therefore received with open arms in many countries of the world. And, as the results of projects in the Netherlands, Denmark, Switzerland and Lithuania, for instance, have clearly shown: this technology has a promising future, for it has so far impressed every customer.