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How to design the perfect karting track
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Bends, throttle-off braking, chicanes, straights... These elements form the basis of every track’s appeal and provide emotions to drivers and spectators. However, someone has to think up, design and then translate them into solid tarmac. Jarno Zaffelli, an Italian engineer who, together with his Studio Dromo, vies with Hermann Tilke for the role of "architect" of the most famous tracks in the world, explains how. Among his works, we find the Autodromo Termas de Rio Hondo, in Argentina, and the modernisation of historic tracks such as Mugello, Imola, Sepang and Monza, as well as the wonderful GoPro Motorplex Mooresville, a US copy of the legendary kart track in Parma.
It depends on the situation. Sometimes there is someone with some property who decides to build a circuit on it, so he designs it as he wishes, with all the mistakes and adjustments of the case. This is how most raceways and kart tracks came to be. Other times the entire project is assigned to a team of professionals and that’s a different approach. The third case scenario is starting from something that already exists, like a piece of road or an old track, and this entails dealing with what you have to turn it into a new concept.
Well, there are no regulatory conditions for curve design on kart tracks, other than lateral and longitudinal plus grade. There is no set rule for the radius. The only limit is set by tarmac laying machines, which require a minimum radius of so many meters, like 6 meters. Below this, the machines can’t turn and lay the material properly. Laying tarmac for kart tracks is tough, because karts pull it up easily. The hairpin is the classic thing you see on a track that has been re-paved or covered over in cement, a tarmac machine working on fresh land can’t guarantee the necessary surface characteristics.
Many people differentiate between slow and fast bends, but it’s more precise to talk about curves with constant radius (a perfect circular arc) or variable radius. So I can draw a closed curve, which means you hit the center hard, then get into the hairpin, and so you have to brake as you bend and steer. Or I can draw an open curve, you go in, slam on the brakes, go through, then immediately give it gas. There is a problem, though, in all this. In real life, curves are used as tools to shape the ideal race line. When tracks are being designed, most people draw a bend, then a straight, then another bend – this is the first huge mistake. Raceways or kart tracks should be drawn and built according to the specific racing line one wants to obtain, they shouldn’t be shaped by curves. Curves are tools to force drivers to follow a specific line, which is why width is a key factor. A curve design that is “slow” at a width of 6 meters becomes a big “fast” bend at 12 meters, because what matters is the racing line, not the shape.
In most cases, track geometry is determined by the characteristics of the construction site. For instance, say you have a long rectangular piece of property, you’ll be better off creating four long straightaways, rather than a zig-zag section on the short end. Get it? It’s about making the best use of what you have. In our example, there isn’t much else you can do: you’ll end up with a very fast section on the perimeter, this will be the perimeter return bend, then long straightaways, and just three hairpins. If the plot is of another shape, you might get up to 50 turns. It also depends on the character you want your track to have. There’s an infinite variety of curve designs to choose from and choose based on the character of your circuit. This is the key thing: you can have the best designed circuit on earth, but if it doesn’t have character, drivers won’t get anything out of it.
It must put them in danger. What's on the outside has to be safe, not the track. Nowadays, though, if there is a dangerous bend...a chicane is positioned before it. And that’s how to destroy it. Yet modern computing systems are able to figure out where a kart may or may not end up and, therefore, it is possible to create a track that is as "challenging" as possible, but safe at the same time. Take Zandvoort, for example: a track dating back to the ‘50s, built in the middle of the dunes, with blind bends and monstrous gradients. Drivers have fun on it, because they understand their difficulties and always go the extra yard. They have to trust themselves, their performance. If they make a mistake, there are escape roads with 30% gradients. The track instils fear, even awe... but it is not justified. Or, rather, it is justified by the track, not by the danger that the driver is faced with.
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