Machines and systems from Wirtgen, Vögele, Hamm and plants from Benninghoven resurface the Silverstone Circuit

3D digital terrain model for circuit optimisation

Eradication of bumps, prevention of aquaplaning and changes to the camber in corners – these were the most important reasons for reprofiling the Silverstone racing circuit. This is why the resurfacing project began with the generation of a 3D terrain model by the Italian circuit design specialists from Studio Dromo and the British lead contractor, Tarmac. This enabled the experts to identify and optimise weak points.

Following acceptance by the operator of the circuit, several total stations transmitted the milling parameters directly to the Wirtgen milling machines in digital form. The advantage of this is that it saves time, assures utmost precision and guarantees highest quality milling results. Because, tolerances in the region of only a few millimetres are decisive, especially in the construction of racing circuits. To ensure that these requirements are met, Wirtgen cold milling machines rely on an intelligent assistance system: LEVEL PRO ACTIVE.

LEVEL PRO ACTIVE forms the basis for high-precision levelling

The levelling system with innovative control panels allows intuitive adjustments. It is fully integrated in the machine control system and, as essential machine functions are directly interlinked, provides a high level of automation.

In combination with the 3D Kit, LEVEL PRO ACTIVE also offers a simple and field-tested interface that is compatible with 3D systems from many well-known manufacturers. This was also the case in Silverstone: Milling parameters from the 3D terrain model were received by onboard laser sensors and autonomously processed by the Wirtgen cold milling machines. ‘With a permissible deviation of ±2 mm over a distance of 13 m, it was clear that we would have to use the latest cutting-edge technologies to deliver the excellent results the client expected’, said Tim Smith, Regional Technical Manager at Tarmac.

Business as usual for the Wirtgen W 210 Fi cold milling machines

During the development of the latest generation of large milling machines, Wirtgen naturally also thought of the operators. For instance, setting up the machines for 3D operations is now very easy. The engineers substantially simplified the mounts for the sensor systems on the weather canopy of the machines. This new system made it much easier for the operators of the two Wirtgen W 210 Fi large milling machines used on the project to do a good job. Although the average milling depth for the whole circuit was 7 cm (2.76 in), it actually varied considerably at almost every point on the racetrack. When the milling was completed, it had taken the highly experienced Tarmac team only four days to remove 87,000 m² of asphalt from the racing circuit.

Benninghoven mixing plants produce high-tech asphalt

The production of the asphalt mix required for the resurfacing project at Silverstone was almost a science in its own right. For example, Tarmac first removed a major proportion of the fines present in the crushed stone by washing. The cleaned stone was then used for the fresh mix produced by two Benninghoven asphalt mixing plants at Tarmac’s Elstow and Harper Lane sites. Despite complex formulations with special bitumen and high-tech aggregates, the plants were able to fulfil the stringently controlled Formula 1 quality standards. The result is a highly durable asphalt surface designed to sustainably resist the extreme lateral loads of hard braking and fast cornering manoeuvres. At the same time, it considerably reduces the risk of new bumps appearing on certain sections of the circuit.

The on-site logistics were just as challenging as the asphalt production. The challenge here was to transport 360 tons of asphalt an hour to the circuit.

Vögele pavers guarantee an asphalt package in Formula 1 quality

The task of paving the new asphalt layers was assigned to teams of Vögele machines. Each of the three SUPER 1800-3i pavers worked in unison with its own MT 3000-2i Offset mobile feeder. Here, the mobile feeders played a decisive role in assuring the required paving performance and quality by eliminating the need for transferring material to the pavers from trucks. While the mobile feeder operators concentrated on transporting the material and liaison with the truck drivers, the paver operators were able to focus exclusively on the actual paving process.

A further contribution to paving quality was made by the deployment of the pavers in echelon formation. The two SUPER 1800-3i pavers on the left and right lanes progressed in a slightly staggered formation behind the paver on the centre lane. The three pavers worked ‘hot-to-hot’ during the paving process to create a continuous, seamless surface across the entire width of the track. Extreme importance was also attached to the excellence of the asphalt surface in other respects. For instance, Tarmac constantly checked and documented whether the paving was carried out within the correct temperature limits. To enable this, all three pavers were equipped with RoadScan, Vögele’s non-contacting temperature-measurement system.

The Hamm heavyweights utilise onboard intelligence during compaction

The technologies from Hamm played a particularly important role in the final compaction of the 3 cm (1.57 in) binder course and the 4 cm (2.76 in) surface layer. Thanks to WITOS HCQ, the HD+ and DV+ series tandem rollers were able to deliver intelligent compaction. ‘HCQ’ – ‘Hamm Compaction Quality’ – is an intelligent compaction system combining several products for the measurement, monitoring, documentation and control of compaction processes. The system monitors compaction progress in real-time and displays it on a screen in the operator’s cabin of the roller.

WITOS HCQ thus increases the efficiency of the compaction process and makes an active contribution to the achievement of flawless surface quality. Proof of this can of course also be provided in cases like the challenging resurfacing project at the Silverstone Circuit: Tarmac achieved full compliance with the stipulated asphalt surface grip characteristic (roughness) of 0.28, calculated on the basis of the International Roughness Index (IRI).