From October 7 to 28, the Bugatti circuit at Le Mans is getting a facelift for 2017 with a complete new surface covering its entire route.
We had already made a first article on the subject but we wanted to take advantage of the winter break to deepen it. So we contacted Mr. Martin Goureau, Head of Track Safety at the Automobile Club de l'Ouest, who very kindly answered our questions. And we did well!
Mr. Goureau, can you explain the problem that led to this work?
“The origin of this work dates back two years. There was then a criticism from the MotoGP riders which was twofold. First, they said the rubber was worn and lacked grip. But mostly they complained that there were a lot of places where there were a lot of bumps, and the bike vibrated or jumped a lot.
What had to be done was to redo the wearing course of the Bugatti circuit which was then more than 10 years old, especially since there were different generations of bitumen linked to certain repairs, such as the Dunlop chicane or the underground. In fact, there were a multitude of things that were problematic, which led to this work. »
What did they consist of?
“We redid the wearing course, that is to say we scraped the bitumen off 3 centimeters, and we put back 3 centimeters of bitumen. »
On the entire circuit?
“Yes, on the entire circuit, which means that today we have a bitumen which only has three joints, instead of the multitude that there was before. »
Why these three joints?
“Because the work was carried out over three days, which is already an enormous achievement. These joints have been placed where there is absolutely no problem; that is to say not in braking zones, and not in turns. Before, the most obvious was the one located at the entrance to the Museum bend, since it arrived after several right turns and sometimes, the tire being colder on the left side, the little "bump" that there was that was enough to make you lose grip, like Marquez last year. This was the most egregious place. »
In total, how long was the work completed?
“In total, in three weeks. It took a week to strip the circuit, then, in collaboration with a laboratory, to remove all the imperfections from the track following the stripping of the circuit. What followed was the preparation phase, then three days to spread the bitumen. With the drying time of the bitumen and then the paints, it took three weeks, which is already exceptional. »
Tell us about the bitumen you put…
“To try to keep it simple, bitumen has three main characteristics. There is the quality of the gravel, where we seek to have particularly sharp gravel, more than on the roads.
Then, there is the quality of the binder, and there, we took a very, very high quality binder which comes from Shell. Then, in the application, but it's a bit technical, there is the PMT, that is to say the Depth of Macro Texture, that is to say how we are going to fill in the gravel so that it corresponds to our expectations. To give an idea, on the road we have a PMT around 0,9 while we are at 0,7. The bitumen is therefore a little more closed and retains a little more water, following work with the tire manufacturers who told us that they did not need the water to be evacuated. They consider that evacuating water is the job of the tire, and that ours is to make bitumen that sticks.
We therefore made a bitumen that was more resistant and had better grip, but evacuated water a little less. »
Have you done any testing on it?
“Yes, in cars, but also with Damien Saulnier’s new GSX-R. We are very satisfied and can't wait to see what happens at the highest level. »
So what ?
“In the wet, the grip is crazy. Really. A crazy grip! With an RS 10, while we passed La Chapelle at 70 km/h in the wet while sliding, now we take it at 110 km/h and it doesn't move. It's really impressive, really impressive! »
How much do you estimate the winnings per round?
“I don't want to get too far ahead of myself but I would say that pole position will be between one and two seconds faster per lap. »
All our thanks to the ACO and Mr. Martin Goureau for this interesting information.
