What should be the speed limit in kilometers per hour when turning on a curve?
4 Answers
The speed should be controlled at 30 km/h when turning on a curve. Basic principles of turning: When turning, the car will generate centrifugal force. When going uphill, the speed is slower, the centrifugal force is weaker, and the center of gravity of the car shifts backward, reducing the degree of understeer and making the direction of the car easier to control. When going downhill, the situation is the opposite. Due to the higher speed, the centrifugal force is stronger, and the center of gravity shifts forward, increasing the degree of understeer. Techniques for turning: Maintain an "outside-inside-outside" turning path. The safest and most time-efficient route when turning is "outside-inside-outside." When driving at high speed, before turning, you should first drive along the outer lane, then move to the inner lane in the middle, and then cut back to the outer lane.
When driving on mountain roads, I pay special attention to the speed on curves. There's no fixed standard for this, but I can share some experience. You need to consider how sharp the curve is, visibility conditions, and whether there are hazards like gravel or water on the road—all these factors affect speed. On regular road curves, I usually keep it around 40 km/h, while for highway ramps, it's advisable not to exceed 60 km/h. The key is to slow down before entering the curve—avoid braking mid-curve, as this can cause the car to skid or lose control. In rainy conditions or at night with poor visibility, reducing speed by another 10 km/h is safer. Remember, how fast you take a curve depends entirely on your judgment, and safety should always come first.
Every time I teach beginners to drive, I emphasize the importance of cornering speed. The appropriate speed for a turn depends on factors like the curve radius, road conditions, and traffic environment. For small urban road turns, around 30 to 40 km/h is suitable, while larger rural curves can handle speeds up to about 50 km/h. What worries me most is beginners cutting corners, so I remind them to ease off the accelerator at least 50 meters before entering the turn. Extra caution is needed for cars with severely worn tires, as reduced grip increases the risk of skidding. Here’s a tip: focus on the exit point of the turn while steering, and your hands will naturally follow your gaze for smoother handling. Poor speed control is the leading cause of accidents in curves—taking it slow never hurts.
From a physics perspective, the reason for speed limits on curves is simple: the faster you go, the greater the centrifugal force. I remember a rough formula where the safe cornering speed is approximately 0.3 times the radius of the curve. For example, a sharp 10-meter radius turn should be taken at 30 km/h, while a wide 50-meter radius curve allows speeds up to around 60 km/h. In rainy conditions when friction coefficient is halved, speeds should also be reduced by half. Front-wheel-drive cars tend to understeer, requiring earlier steering input, while rear-wheel-drive cars have higher risks of oversteer and require careful throttle control. The most crucial factor is sensing the vehicle's dynamics - if the seat pushes you outward or the tires start screeching, it's time to ease off the throttle.
