State-of-the-art technology for the Baku city circuit

Whenever the 22 Formula 1 pilots race around the track, vying for pole position, the air in one of the many metropolises around the world is charged with excitement. In June 2016, Baku, the capital city of Azerbaijan, got its first taste of this heady cocktail of top speeds, precision and thrills, glamour and celebrations. This spring, a city circuit was created in the centre of the capital, on the “balcony of Europe” amid the centuries-old buildings, contemporary high-rise towers and the port on the Caspian Sea. To make sure that the pilots can safely keep their powerful 815hp (600kW) racing cars on the track, WIRTGEN, VÖGELE and HAMM machines built a high-quality asphalt pavement on the narrow streets and the wide boulevards of the city.

First choice for the top league

Formula 1 races make the highest demands on the pavement. The asphalt must be particularly homogeneous and even – and naturally have an outstanding grip. Ideally, such circuits are paved on a defined sub-base. This was not possible in Baku, however, as the circuit passes straight through the city. At the beginning of the year, the streets were a mixture of normal, asphalt roads and historic cobblestones.

Special formula for the ancient cobblestones

As a feature of a UNESCO World Heritage site, the historic cobblestones had to remain intact and be restored to their original glory after the race. “We solved this unusual challenge by separating the cobblestones from the asphalt with a layer of chippings. A pavement of base course, binder course and surface course was then paved. In the cobbled areas, a carbon-reinforced asphalt layer was integrated into the surfacing. It was designed to prevent the new asphalt pavement shifting over the cobblestone,” explains Dr Rainer Hart, an asphalt consultant.

On the other circuit sections, the contractor, AzVirt LLC from Baku, employed 3D-precision milling to create an exact, precisely pre-defined profile that met Formula 1 standards on the existing city roads.

Eight SUPER 1900-2 pavers with AB 600 TV Extending Screed

The binder and surface courses were then paved onto the previously prepared roadways. This was accomplished by an impressive armada of VÖGELE pavers and 15 HAMM rollers, with the machines sometimes working simultaneously on different sections; all in all, 8 SUPER 1900-2 pavers were used, each equipped with an AB 600 TV Extending Screed. The use of identical screed types was stipulated in the contract.

Perfect logistics

During paving, the asphalt production, transport and feeding were controlled so as to ensure that the pavers were able to work at an almost constant pave speed. More than 40 lorries transported the asphalt from three mixing plants to the pavers. Due to their careful preparation and planning, AzVirt were able to supply asphalt to the pavers just in time without stoppages, despite the difficult traffic situation in the city centre - an impressive feat of logistics and civil engineering.

Seven at one blow

The absolute highlight was the “hot to hot” paving in the area of the seafront, where 7 pavers plus 15 rollers featuring operating weights of between 2 and 14t built the asphalt pavement for the track and the spectator area in a single step. Their combined width spanned 52m – a true highlight for all involved!

HD, HD+ and HD CompactLine for high-quality compaction

The AzVirt experts know that final compaction has a decisive influence on the surface quality of the asphalt pavement. With this in mind, they exclusively used HAMM tandem rollers of the HD, HD+ and HD CompactLine series. The design of the articulated rollers already ensures a regular weight distribution – a key factor for outstanding pavement evenness without bumps and cracks. An added advantage is the excellent side clearance combined with the large track offset. Ideal for ensuring consistently precise and full compaction along curbs, road fittings and walls.

Safe and effective with unique visibility

All HAMM rollers feature outstanding visibility. On the HD+, this is guaranteed by the clever frame construction combined with the panoramic cabin. The compact machines of the HD CompactLine range provide drivers with a full view of the working area at all times due to the slim-line front end. This not only influences quality, but is also a safety aspect, particularly when a large number of rollers closely follow the pavers as in Baku.

Protecting historic buildings

Another decisive factor for the quality of the compacting work in Baku was the use of oscillation rollers. They cause significantly lower levels of vibration to the surrounding area than vibratory rollers. The invitation to tender specified oscillation compaction, as the entire circuit is flanked by century-old buildings. In addition, there are gas pipes as well as underground car parks and tunnels under many of the roads. Vibration compaction was therefore an absolute no-go in most areas. For Manfred Martin, Head of the AzVirt Technical Division, there was no alternative to the HAMM rollers: “As a pioneer in this field of technology, HAMM have more than 30 years of experience with oscillation – much more than any other manufacturer.”

Final finish with oscillation compaction

However, oscillation has a great deal more to offer than “just” low-vibration compaction. The special drum movement also creates even surfaces with a good initial grip – the second key point in favour of using oscillation in Baku.

The best city roads in the world

Oscillation compaction was also the first choice for the surface course of the F1 circuit, as areas compacted with oscillation have an excellent longitudinal evenness. The final quality control to check the position and evenness of the track showed that AzVirt had built a superb pavement on the originally inhomogeneous city roads and easily met the stringent surface accuracy requirements of 3mm over a distance of 4m.

Oscillation

Low-impact methods for the city
On city-centre job sites with confined conditions, dynamic compaction with oscillation is recommended, as it only introduces around 15% of the vibrating force into the surrounding area in comparison to vibration. This protects the surrounding buildings as well as the pipes and installations below the pavement.

ADVANTAGES

  • Low vibrating forces in the area around the machine
  • Dynamic compaction, also for vibration-sensitive areas

Perfect surfaces for Formula 1 races
Surfaces that are compacted with oscillation feature a very high degree of longitudinal evenness. This is because the drum is in constant contact with the ground. This type of asphalt compaction also produces an excellent initial grip, as the drum rubs the bitumen on the upper surface of the pavement with its oscillating movement. A clear bonus when it comes to safety.

ADVANTAGES

  • Excellent longitudinal evenness, no irregularities in the surface
  • High level of initial grip

Job site details

Conversion of the city roads to a Formula 1 circuit in Baku, Azerbaijan

Length of the circuit: 6,003m
Width of the circuit: 7.5 – 19m
Asphalt-paved area: 113,400m²
Slope: +12% to -9%
Working parameters  
Paved material quantity  
Binder course: 10,400t
Surface course: 11,600t
Layer thickness  
Binder course: 5cm
Surface course: 4cm
Material  
Binder course: AC 16 BS SG
Surface course: AC 11 RT
Equipment  
1 WIRTGEN W 2100 milling machine
8 VÖGELE SUPER 1900-2 pavers with AB 600 TV Extending Screed
4 HAMM HD+ 110 VO tandem rollers
4 HAMM HD+ 90 VO tandem rollers
2 HAMM HD 110 tandem rollers
2 HAMM HD 90 tandem rollers
2 HAMM HD 10 tandem rollers
1 HAMM HD 14 tandem roller
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