Vehicle Braking Distance: Everything You Need to Know

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Imagine how many fewer accidents there would be if cars could stop instantly. Unfortunately, elementary laws of physics say this is impossible.

It is customary for car manufacturers to “brag” about another indicator: acceleration speed up to 100 km / h. Of course, this is also important. But it would be nice to know how many meters the braking distance will stretch. After all, it is different for different cars.

Vehicle Braking Distance: Everything You Need to Know

In this article, we will tell you what every driver needs to know about braking distances in order to be safe on the road. Buckle up and let's go!

What is the stopping distance of a car?

The braking distance is the distance that the vehicle travels after activating the braking system until it stops. This is only a technical parameter by which, in combination with other factors, the safety of the car is determined. This parameter does not include the driver's reaction speed.

The combination of a motorist's reaction to an emergency situation and the distance from the start of braking (the driver pressed the pedal) to a complete stop of the vehicle is called the stopping distance.

Vehicle Braking Distance: Everything You Need to Know

The traffic rules indicate the critical parameters at which the operation of the vehicle is prohibited. The maximum limits are:

Transport type:Braking distance, m
Motorcycle / moped7,5
A car14,7
Bus / truck weighing up to 12 tons18,3
Truck weighing more than 12 tons19,5

Since the magnitude of the braking distance directly depends on the speed of the vehicle, the above-mentioned distance traveled by the transport when the speed decreases from 30 km / h is considered a critical indicator. (for motor vehicles) and 40 km / h. (for cars and buses) to zero.

Vehicle Braking Distance: Everything You Need to Know

Too slow a reaction of the braking system always leads to damage to the vehicle and often to injuries to those who are in it. For clarity: a car moving at a speed of 35 km / h will collide with an obstacle with a force identical to that of a fall from a five-meter height. If the speed of the car when colliding with an obstacle has reached 55 km / h, then the impact force will be identical when falling from the third floor (90 km / h - falling from the 9th floor, or from a height of 30 meters).

These research results show how important it is for a motorist to monitor the condition of the vehicle's braking system, as well as tire wear.

What is the stopping distance formula?

Vehicle Braking Distance: Everything You Need to Know

There are special formulas that help the driver calculate the braking distance during emergency and normal braking. Of course, they are averaged.

So, normal braking involves gently pressing the brake pedal, for example at a traffic light. In this case, we are guided by the formula:

(Speed, in km / h: 10) * (speed, in km / h: 10) = braking distance in meters

That is, if you are traveling at 50 km / h, the braking distance will be approximately 25 meters. We count like this: 50/10 * 50/10 = 5 * 5 = 25.

In emergency braking, the value obtained is divided by two more. The formula looks like this.

(Speed, in km / h: 10) * (speed, in km / h: 10) / 2

Let's count on a specific example. Let's say you are again moving at a speed of 50 km / h and a situation has occurred in which you urgently need to brake. We consider the braking distance as follows: 50/10 * 50/10/2 = 5 * 5/2 = 12,5 meters.

You might say that in an emergency there is no time to count and you need to act. Yes, you are absolutely right. But there is one "but". Each driver moves around the city at approximately the same speed. Therefore, you can learn the desired value in advance and start from it when needed. Such a simple life hack can one day save someone's life. So take note of it.

How to calculate total stopping time and total stopping distance?

As we noted above, the driver needs time to make a decision about braking. That is, to react. Plus, it takes time to move your foot from the gas pedal to the brake pedal and for the car to react to this action.

There is a formula that calculates the average driver's reaction path. There she is:

(Speed ​​in km / h: 10) * 3 = reaction distance in meters


Let's imagine the same situation. You are driving at 50 km / h and decide to slow down smoothly. While you are making a decision, the car will travel 50/10 * 3 = 15 meters. The second value (the length of the real stopping distance), we considered above - 25 meters. As a result, 15 + 25 = 40. This is the distance that your car will travel until you come to a complete stop.

What factors affect braking and stopping distance?

Vehicle Braking Distance: Everything You Need to Know

We already wrote above that many factors influence the stopping distance. We suggest considering them in more detail.

Speed

This is the key factor. This means not only the driving speed of the car, but also the speed of the driver's reaction. It is believed that everyone's reaction is about the same, but this is not entirely true. The driving experience, the state of human health, the use of medicines by him, etc. play a role. Also, many "reckless drivers" neglect the law and are distracted by smartphones while driving, which, as a result, can lead to disastrous consequences.

Remember one more important point. If a car's speed doubles, its stopping distance quadruples! Here the 4: 1 ratio doesn't work.

Travel circumstances

Undoubtedly, the condition of the road surface affects the length of the braking line. On an icy or wet track, it can grow at times. But these are not all factors. You should also be wary of fallen leaves, on which the tires glide perfectly, cracks in the surface, holes, and so on.

Tires

The quality and condition of the rubber greatly affects the length of the brake line. Often, more expensive tires provide better grip on the road surface. Please note that if the tread depth has worn out more than the permissible value, then the rubber loses the ability to drain a sufficient amount of water when driving on a wet road. As a result, you may encounter such an unpleasant thing as aquaplaning - when the car loses traction and becomes completely uncontrollable.

To shorten the braking distance, it is recommended to maintain optimal tire pressure. Which one - the automaker will answer you this question. If the value deviates up or down, the braking line will increase.

Depending on the coefficient of adhesion of the tires to the road surface, this indicator will be different. Here is a comparative table of the dependence of the braking distance on the quality of the road surface (a passenger car whose tires have an average coefficient of adhesion):

60km / h80 km / h90 km / h
Dry asphalt, m.20,235,945,5
Wet asphalt, m.35,462,979,7
Snow-covered road, m.70,8125,9159,4
Glaze, m.141,7251,9318,8

Of course, these indicators are relative, but they clearly illustrate how important it is to monitor the condition of car tires.

Technical condition of the machine

A car can only enter the road in good condition - this is an axiom that does not require proof. To do this, carry out routine diagnostics of your car, make timely repairs and change the brake fluid.

Remember that worn out brake discs can double the braking line.

Distraction on the road

While the car is in motion, the driver has no right to be distracted from driving the vehicle and controlling the traffic situation. Not only its safety depends on this, but the lives and health of passengers, as well as other road users.

Here's what happens in the driver's brain when an emergency occurs:

  • assessment of the traffic situation;
  • decision making - to slow down or maneuver;
  • response to the situation.

Depending on the innate ability of the driver, the average reaction speed is between 0,8 and 1,0 seconds. This setting is about an emergency, not an almost automatic process when slowing down on a familiar stretch of road.

Vehicle Braking Distance: Everything You Need to Know

To many, this time period seems insignificant to pay attention to, but ignoring the danger can lead to fatal consequences. Here is a table of the relationship between the driver's reaction and the distance traveled by the car:

Vehicle speed, km / h.Distance until the moment the brake is pressed (the time remains the same - 1 sec.), M.
6017
8022
10028

As you can see, even a seemingly insignificant second of delay can lead to sad consequences. That is why every motorist should never break the rule: "Do not get distracted and stick to the speed limit!"

Vehicle Braking Distance: Everything You Need to Know

Various factors can distract the driver from driving:

  • mobile phone - even just to see who is calling (when talking on the phone, the driver's reaction is identical to that of a person in a state of light alcoholic intoxication);
  • looking at a passing car or enjoying the beautiful scenery;
  • wearing a seat belt;
  • eating food while driving;
  • falling of an unsecured DVR or mobile phone;
  • clarification of the relationship between the driver and the passenger.

In fact, it is impossible to make a complete list of all the factors that can distract the driver from driving. In view of this, everyone should be careful about the road, and passengers will benefit from the habit of not distracting the driver from driving.

What is the braking distance at speeds of 50, 80 and 110 km / h.

As you can see, due to the many variables, it is impossible to create a clear table describing the exact stopping distance of an individual vehicle. This is influenced by the technical condition of the car and the quality of the road surface.

Vehicle Braking Distance: Everything You Need to Know

Average braking distance of a passenger car with a working system, high-quality tires and a normal driver's reaction:

Speed, km / h.Approximate braking distance, m
5028 (or six auto bodies)
8053 (or 13 car bodies)
11096 (or 24 buildings)

The following conditional situation shows why it is important to adhere to the speed limit and not rely on "perfect" brakes. To stop in front of a pedestrian crossing from a speed of 50 km / h to zero, the car will need a distance of almost 30 meters. If the driver violates the speed limit and moves at a speed of 80 km / h, then when reacting at a distance of 30 meters before the crossing, the car will hit a pedestrian. In this case, the speed of the car will be about 60 km / h.

As you can see, you should never rely on the reliability of your car, but it will be correct to adhere to the recommendations, because they are taken from real situations.

What determines the average stopping distance of any car

Summing up, we see that the braking distance of any car depends on a combination of such factors:

  • vehicle speed;
  • machine weight;
  • serviceability of brake mechanisms;
  • coefficient of adhesion of tires;
  • the quality of the road surface.

The driver's reaction also affects the stopping distance of the car.

Considering that in an emergency, the driver's brain needs to process a lot of information, adhering to the speed limit is the very first commandment, the importance of which will never cease to be discussed.

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