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Stopping distance

Safety, calculation of stopping distance

There are many factors such as the condition of the road and the braking system of the vehicle, which can affect the stopping distance of a passenger vehicle, but usually, under normal road conditions, if you are traveling at a speed of 30 km / h, your stopping distance is 45 meters. Your speed to 60 km / h, the kinetic energy of your vehicle is square, so the distance to stop your vehicle is also four times (4X45 = 180).

Also, keep in mind that most people, on average, take seconds to react to a dangerous situation until the brakes are applied, so you will also need to add the time distance to react and apply the brakes.

Example: If you are traveling at 60 mph, you are driving at 17 meters per second (60: 3.6 = 16.6). Therefore, if it takes you one second to react to danger and apply your brakes, you will need to add 17 meters to the above number For stopping distance (180 kinetic energy requirements + 17 meters reaction time = 197 meters).

Difference in distance from 100 km / h (real world test)

Be careful when comparing results as test results can vary depending on many factors, including surface area, how speed is measured (as different cars have different speed indicators), tire pressures, fuel load and whether the car was just a single driver or there were additional passengers.

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6 Replies
Zoomup
3988 Posts

So the moral is: do not drive too closely to the car in front. Leave plenty of braking distance. Also, do not drive too fast as the unexpected can and does happen, such as a child or animal running out in front of your car.

Z.

MrFox
29 Posts

There's a distinct lack of rocket science here, Z. :) And yet, idiots everywhere. Remember, 50% of the population is below average intelligence.

Good Morning,
What do you mean lack of science (menu) ?
MrFox
29 Posts

Benyamin, I don't mean that your post lacks science. It is succinct and informative, thank you. What I mean is that following Z's comment, the rule of thumb is drive sensibly, defensively, and leave plenty of room. And yet, most people don't. Because idiots.

I understand, but do not forget that now is winter and there is a difference to summer so I bring up the knowledge of it. 
Thank you

Benyamin Davodian: 

Also, keep in mind that most people, on average, take seconds to react to a dangerous situation until the brakes are applied, so you will also need to add the time distance to react and apply the brakes.

It is well to quantify that. 

German road law specifies a standard reaction time of 1s. The aerospace people who have looked at this closely say between 1s and 2s. 

1s is probably Lewis Hamilton standard. If the event is something unexpected, say a child or animal, nearer 2s is a better guess. Even at 30mph, that is a lot of space under the wheels before you start to brake. 

Because of that, I think that residential areas are better served with a limit of 20mph (or 30kph, as often here in Germany - but unfortunately not all that often adhered to).

 

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