Zandvoort: The "problem" which created the steep bends

"It all started with a problem.“ This is how track manager Niek Oude Luttikhuis describes the first talks with Formula 1 about a possible return to Zandvoort. And that is the story of this problem, an extraordinary idea and its implementation. Or in a nutshell: How the F1 track in Zandvoort got its steep curves.

Such a thing had not yet been a topic in 2018, but when Zandvoort first put out its feelers in the direction of F1 again, Max Verstappen had already won a handful of grands prix and was well on his way to becoming a hero in the Netherlands. So why not set up a home race for the upcoming superstar?

What the 'Verstappen effect' could achieve had already been seen at F1 circuits abroad - and also at the Jumbo Race Days in Zandvoort, where thousands watched Verstappen do demo laps in an F1 car. A race of its own seemed like the next logical step.

F1 saw charm in it. "But they didn't want to sign a contract with us because we didn't have a long straight and therefore no long DRS zone that would have favoured overtaking - like on almost all newly built tracks," says Luttikhuis.

The Bahrain International Circuit, as an example of a modern grand prix circuit, has a straight that is more than one kilometre long. Zandvoort, on the other hand, came in at only 700 metres.

So, what could be done to meet the requirements of F1? "The easiest thing would have been to extend the straight," says Luttikhuis, "but that's not possible in Zandvoort. Because on one side there are sand dunes worth protecting and on the other side the town of Zandvoort. We could not extend the straight."

F1 management therefore suggested activating the drag reduction system (DRS) already in the Arie-Luyendyk curve, in the finishing curve. "But with that we had the problem that the permissible centrifugal forces would have been exceeded in the finishing bend," says Luttikhuis. "The cars would simply have become too fast at the exit of the bend."

So other approaches were discussed, 15 different options in all. "One suggestion, for example, was to make the corner before it extremely slow, almost like a 90-degree bend. That would allow the cars to come out of that corner very slowly, which in turn could allow the use of DRS in the finishing corner," explains Luttikhuis.

Renovations at the Dutch race track in Zandvoort 2020

Photo by: Chris Schotanus

But calculations showed that the basic problem remained in each case. The centrifugal forces at the exit of the finishing bend would have been higher than F1 specifications allowed. Zandvoort was faced with a dilemma.

"But at some point I thought: ‘Why don't we do it like in Indianapolis and put in a steep curve’," says Luttikhuis. "Because then some of the forces would be directed downwards."

What inspired him to take this approach? "I've been to Monza before, also on the banking. But did I have that in mind? I don't know. Maybe I was also inspired by the electric car racing track I used to have as a little boy!"

One way or another the Zandvoort track manager soon submitted the idea to F1. "I received an answer on the same day. The tenor: 'Yes, that could be the solution! We were supposed to create a simulation. And that's where the architects and engineers from Dromo came in."

How did Jarno Zaffelli, founder and CEO of Dromo, react when he heard about the unusual proposal for a steep curve? "I was downright ecstatic," says the Italian. “I thought to myself, ‘finally there was someone who was fully passionate about it, come what may’, because sometimes you have to be a little crazy."

He was immediately fascinated by the technical challenge: "It was about virtually extending the straight, but without changing the track layout. So in principle we had to develop a new kind of track, with completely different key figures, with a slightly different twist."

Luttikhuis and Zaffelli were immediately on the same wavelength. "If you react positively when confronted with something new, then you already have a good attitude," says Luttikhuis. "Then you know, this company thinks like you and not first of potential problems. Dromo has simply taken on this task."

Zaffelli admits: "Building a steep curve in this way was a first for us. We had already designed something similar for a test site and for smaller projects, but every project is individual. That means every time is a first time, no solution can be built 1:1 somewhere else. Every design is a prototype.”

Renovations at the Dutch race track in Zandvoort 2020

Photo by: Circuit Park Zandvoort

But Dromo did find inspiration elsewhere. "The first step was to look for examples. Every steep curve in Europe, including the very first ones like at Monza, Brooklands or Sitges-Terramar. Because the question is how to shape banking."

And for Zandvoort, Dromo would have to reach into the bag of tricks twice, in different ways; the final bend should allow the use of DRS, the Hugenholtz-Bocht [Turn 3] should be a spectacular eye-catcher and an additional, extraordinary overtaking spot.

"This is a unique passage for Formula 1 tracks," says Zaffelli. "That's why we call Zandvoort a 'hypertrack', because there's nothing like it yet."

Zaffelli continues: "We wanted to have different angles of inclination in Turn 3 and therefore we also had to pay attention to the track height in the curves before and after. You have to take all that into account during construction.

"The interesting thing about steep bends is that the banking itself is not the problem, but the driving into and out of the bends. In the past, this transition was usually difficult to manage. But my engineers at Zandvoort have created a masterpiece."

Not only is the location of the track in the North Sea dunes unique, but also the surface on which the track rests: Sand. And its load-bearing capacity is a factor in how it can be built. "It varies by the sea depending on the tides," says Zaffelli. "And you then also have to manage to drain rainwater."

All this under the premise of not interfering too much with the course, as Luttikhuis emphasises: "Zandvoort is an old-school circuit, and we wanted to preserve that look. That meant any changes should not make the track more boring, but more exciting. And we didn't want to end up with a car park with colourful lines."

These were the specifications with which Dromo embarked on the F1 project at Zandvoort. From January to August 2019, the Italian company created several simulations and did preliminary work. "My entire team was involved," says Zaffelli. But the efforts of his 15 employees paid off and the FIA approved the designs for implementation.

Renovations at the Dutch race track in Zandvoort 2020

Photo by: Chris Schotanus

But there were doubts: "There were sceptics in the responsible commission. For example, someone said that it could not be built this way," says Zaffelli.

Luttikhuis was also confronted with resistance: "Some had no confidence in the data. Others had concerns because they knew what had happened in the Indianapolis Grand Prix in the steep corners."

For some observers, the memories of these incidents were too fresh: In 2004, Ralf Schumacher had crashed in the steep bend after a puncture and suffered a concussion. In 2005, the Michelin-shod teams couldn’t start the race due to safety concerns, and only six Bridgestone cars raced.

"There were reservations," says Luttikhuis. And with that, it was up to Zandvoort and Dromo to convince the doubters of the feasibility of their ideas by making the project a reality.

That happened at the end of 2019 and beginning of 2020: "We only needed four months from November to February for the complete construction phase," says Zaffelli. "And you can imagine what the season meant." Namely, single-digit temperature values, double-digit rainy days per month as well as the fewest sunshine hours in the year.

Around 200 workers from Dromo, Zandvoort and a local construction service provider were involved in the construction phase. "Thanks to our good preparation, we did it in that time," says Zaffelli.

Just how big the modifications really were is shown by the example of Turn 3. "There we decided on a steep turn because we needed more space behind it for the passage between paddock one and paddock two," explains Luttikhuis.

Zaffelli: "We raised Turn 2 slightly, lowered Turn 3 slightly and raised Turn 4 slightly again. In addition, we moved Turn 3 by a total of 16 metres, but this meant a net gain in space of only two metres due to banking, safety structures and the like. But in return, Zandvoort now has a unique selling point with this curve."

Renovations at the Dutch race track in Zandvoort 2020

Photo by: Chris Schotanus

Luttikhuis can confirm that. He says the two steep corners did "a lot of good" for Zandvoort right from the start. "We already had a lot of participants at the first race after the reopening. The rush was enormous."

But the steep curves are not only popular with racers: "Tourists also come over and take a look at the banking. They are always drawn there on track walks or tours. It's a crowd puller, day and night. Most people just want to stand in the banked curve."

Those responsible had not expected such enthusiasm. "For us, the steep curves were a necessity. And we thought it would be cool," says Luttikhuis. But the expectations were exceeded in every respect.

Only one thing "didn't work out as planned", Zaffelli admits with a laugh: "I lost a bet against an F1 technician."

The bet was whether overtaking would take place in the new Turn 3. "He said no one would overtake at this point, I disagreed. And of course: in the first year [2021] there were no overtaking manoeuvres in Turn 3." So the bet was lost for Zaffelli.

"We had designed the curve for the new cars, not the old ones. And from the second year onwards [under the new F1 regulations] overtaking actually took place in Turn 3. But that didn't help me any more for the bet."

The postponement of the new technical regulations in F1 from 2021 to 2022 was also a reason why DRS was not allowed at its full extension in the first year in Zandvoort on the main straight, because the plan was tailored to the new generation of cars.

The transition from flat track to steep curve was therefore designed in such a way that as many vehicles with four wheels as possible can cope with it. The layout is only unsuitable for motorbikes because "steep curves are not for two-wheelers," says Zaffelli.

Renovations at the Dutch race track in Zandvoort 2020

Photo by: Chris Schotanus

But steep curves are very much a topic for other race tracks in Europe. Zandvoort has shown that and Dromo senses it from the demand: "We now get a lot of calls from people who have become aware of us through Turn 3," says Zaffelli. He and his team currently have several tracks with steep bends "in the pipeline".

Zaffelli does not reveal which projects are involved in detail. Only this much: The planned F1 circuit in Madrid could also include a steep curve "because there, just like in Zandvoort, the FIA specifications for lateral forces are exceeded. We are therefore trying to solve the passage in a similar way as at Zandvoort."

But Zaffelli emphasises again that there will not be a direct copy to follow. "Every case is unique and the factors are too different in each case anyway.”

In the short term, Dromo has other tasks at Zandvoort. Before the 2023 F1 race, some bumps had to be removed and changes made to the FIA catch fences. "Nothing major," emphasises track manager Luttikhuis.

In the medium term, however, excavators will be moving into Zandvoort again: "After the grand prix, we will extend the pitlane.

This is to give the individual cars more space during the pitstop, explains Zaffelli. "Other than that, we haven't really had to do much since the conversion." And that speaks for the track and steep curve design of the first "hypertrack".

Or as Luttikhuis puts it: "Our steep curves are something new, and they are very well received."