The secret behind Zandvoort’s banked corners

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The Formula One field is more than ready to return in Netherlands after a 36-year hiatus with the iconic Zandvoort circuit set to host the Dutch Grand Prix this weekend.

This weekend will see the Formula One field race again in the Netherlands on the legendary Zandvoort circuit, that has hosted all the 30 editions of the F1 GP of Netherlands from 1952 to 1985. The track was set to make its return on the F1 schedule last year, but the organizers decided against hosting a race behind close doors.

With the situation regarding the Covid-19 pandemic showing sings of improvements thanks to the vaccination, Zandvoort can welcome around 70,000 spectators supporting the local hero Max Verstappen.

The track, which is a big challenge with its unique, flowing nature, has hosted a raft of different series recently including DTM, Formula 4, WTCC, Formula 3 in recent years. Although drivers are rewarded with a breath-taking experience while navigating their cars through the flowing corners, overtaking opportunities are at a premium at the challenging track.

After Formula One decided to come back to the legendary Dutch circuit, the FIA and the FOM asked the circuit owners and the race promoter to make tweaks to the track in order to promote overtaking. The FOM proposed to increase the length of the main straight, but it was not possible as it would have impacted on one side with the Natural Park Natura 2000 and on the other with holidays’ houses.

Jarno Zaffelli, head of an Italian engineering company specialised in racetrack design and construction, was the man chosen by the circuit management and in particular by Niek Oude Luttikhuis, the track manager, to make something unique: a new ‘old-school’ circuit.

“I have always had a special connection with Zandvoort because its former Director, Hans John Hugenholtz, designed Suzuka – one of my favourite tracks – back in 1962,” started Zaffelli.

“Although he died in 1995 and unfortunately, I haven’t had the chance to meet him in person, I wanted to learn from him, so 5 years ago I visited the track. I was welcomed by Niek Oude Luttikhuis, the track Manager. We did a lap of the track and started to discuss about how this or that corner could be improved. This is how it all started”.

Four years later, as the idea to host a Formula One race became real, Jarno Zaffelli was called to update the track. “With Jarno it was the perfect match because we were sharing the same philosophy”, stated Niek Oude Luttikhuis, the track manager. “We wanted to do something innovative, but in the old-school style. This was the main brief. This vision was supported by FOM too”.

“We like to design tracks that reflect the feeling and the perception that you get when you drive. We are driven by the desire to translate into straights, corners, curbs and bankings the adrenaline of a lap. Our philosophy is to design a track that is perceived as a big challenge and scare the drivers. Then of course they have to be objectively safe and in this the FIA is of paramount support in assessing our calculations.

“We want a rollercoaster effect”, asked the circuit management. “We are the right guys” answered Dromo team, “the challenge was to do this, enhancing the soul of the existing track”.

To increase the overtaking opportunities, Luttikhuis came up with the idea of banked corners.

“The idea to have a gentle curve was not effective because the corner speed of the cars was too fast and at the end of the corner, the F1 lateral acceleration in the last corner was over 2,5 G and the DRS could not be open”, explained Zaffelli. “The horizontal forces of the car were the key, so Niek came up with the idea to explore the feasibility to reduce the forces by inclining the track, up to a point so that the lateral acceleration was below the 2.5 G”.

So the third dimension might be the solution. “According to the FOM vehicle dynamic simulations, we had to do an inclination of at least 15 degrees in that corner.” Jarno concluded; “FIA was going to approve it if we could prove that was possible to be designed and built properly.”

Together with KWS, the building company, Dromo studied all the technical details, including the formula of the “FlyingDutch”, the name of the bespoke asphalt mix of Norwegian stone and Shell bitumen that they created to meet the characteristics of the Zandvoort’s sand, the cold temperatures, the strong winter winds and the stress of the F1 cars, suitable to pave the bankings with the available machines.

The “extension” of the main straight was achieved by modifying Turn 14, the last corner. The wide angle and the banking with up to 18 degrees of elevation (34%) creates in fact an extension of the main straight. According to Dromo’s calculation, it will increase the point where the Formula One drivers can go flat out by 340 metres, transforming the actual 678 metres in a potential 1 km straight. This will allow an overtaking point at the braking of Turn 1, the famous Tarzan.

“The feeling of the banking is amazing, it’s like accelerating on a side of dune”, confessed Jarno Zaffelli, who had to face the technical challenge that the FIA guidelines state that no banking should be over 10%.“

The reconstruction work was completed within three months.