Why does road racing tracks and circuits have curbs?

Question

Seems to me they're very bumpy and often cause the cars to be unstable. Sometimes they even cause mechanical damage. Why do race tracks need them? can't they just paint the edge of the track and not put the bumpy curbs in?

Prevention of track cutting could be it. But in some places like Monaco where walls would do a excellent job prevent cutting, they still put in curbs.

Answer 1

This question requires a multi-purpose answer:

1) Curbs serve as a visual and reference points for drivers

2) Curbs have the function to delimit a turn or a portion of it

3) They serve also as deterrents for cutting corners, especially in chicanes

4) They present technical difficulties for drivers. Drivers can ride curbs, but not jump them. You can't overdo a curb as it would result in lack of downforce, a lack of balance, weight and traction, or ultimately lose the car completely

5) If taken properly and gliding on them, curbs can actually improve speed in corners, and mainly allow to achieve faster speed out of the corners. You can use curbs at your advantage. But they are tricky

Basically, to manage curbs in a racing track is an art. Who does it best usually wins races. If they would just paint instead of creating curbs, they would leave out many challenges that drivers have to cope with in order to be successful. A good driver loves curbs in a track.

Answer 2

That guy with the long answer has a good one.
Besides everything he said, which is true, I'll add #6, which is when you're driving a car (I can vouch for this in touring cars, I don't have a lot of experience in open-wheel), your vision is limited by your helmet, seat, nose of the car, etc., and a great deal of your awareness of where your car is on the track is done by feel and by judging from what you can see some distance out in front of you. I can see the edge of the road ahead, not right under my front wheel. But I can feel a curb, and once I'm familiar with my ride and the circuit, I can feel how high I should be going on it to get a good run through a corner. It is a bit of an art. Without the curb, it would be a whole lot easier to go too far and skate through the grass. The challenge is, as was mentioned, to use the curb but not overdo it, because it can do damage. Watch a WTC race sometime; they bang the hell out of the curbs, even more so than F1 cars.

Answer 3

Curbs serve the same purpose all over the world, namely to warn drivers they are too close to something (a wall, a fense, grass, or sand).

In road racing there are no rules that stipulate a driver must drive over curbs. Drivers do it because in many cases, it is the quickest way to get around a corner. Drivers who use curbs can carry a greater rate of speed entering the corner. The contact with the curb or "going over the curb" is done on purpose in order to reduce the rate of speed on one side of the car. Doing this allows the car's speed to be reduced rapidly. The contact with the curb also acts as a pivot point to swing the non-curb side of the car around quickly.

In Rallying where there are no curbs but instead there are ditches, the drivers use a similar techque call "ditch hook".

Answer 4

To discourage short cutting the corners.