It may happen that the integrity of the car body and the safety of its passengers will depend on the length of the braking distance. A car at speed simply cannot freeze abruptly after pressing the brake, even if it has high-quality tires and efficient system braking. After the brake pedal is pressed, the car in any case overcomes a certain distance, and this distance is called the braking distance.
The driver must constantly calculate the length of the braking distance in accordance with one of the rules for traffic safety, which says that the braking distance must be less than the distance to the obstacle.
In this situation, it all depends on the reaction and skill of the driver, the sooner he presses the brake and correctly calculates the length of the braking distance, the sooner, and more successful than a car slow down.
Braking distance of the car at a speed of 60 km / h
Deformation of the body in a collision at a speed of 60 km / h
Stopping distance also depends not only on the driver, but also on other related factors: on the quality of the road, speed, weather conditions, condition brake system, brake system devices, car tires and many others.
note that weight passenger car does not affect the length of the braking distance. This is due to the fact that the weight of the car increases the inertia of the car when braking, preventing braking, but increases the grip of the tires due to the increased mass of the car.
These physical properties compensate each other, while practically not affecting the length of the braking distance.
The speed of braking directly depends on the method of braking. sharp brake to the stop, will cause the machine to skid or skid (if the machine is not equipped with an ABS system).
Gradual pressing on the pedal applied when on the road good visibility and calm environment, it is not suitable for emergency situations. When pressed intermittently you can lose control, but then stop quickly. Also possible stepped pressing(similar in effect to ABS system).
There are special formulas that allow you to determine the length of the braking distance. We will try to calculate the formula for different conditions, depending on the type pavement.
Formula for determining the stopping distance
Braking distance on dry pavement
We remember the lessons of physics, where ? is the coefficient of friction, g is the free fall acceleration, and v is the speed of the vehicle in meters per second.
The situation is as follows: the driver is driving car Lada whose speed is 60 km/h. Literally 70 meters away is an elderly woman who, forgetting about safety rules, hastily catches up with fixed-route taxi(standard situation for Russia).
Let's use this very formula: 60 km/h = 16.7 m/sec. Dry asphalt has a friction coefficient of 0.7, g - 9.8 m/s. In fact, depending on the composition of the asphalt, it is from 0.5 to 0.8, but still take the average value.
The result obtained by the formula is 20.25 meters. Naturally, this value is only relevant for ideal conditions when the machine is equipped with quality rubber And brake pads, the braking system is in good condition, when braking you do not go into a skid and do not lose control, from many other idealized factors that are not found in nature.
Also, to double-check the result, there is one more braking distance formula:
S = Ke * V * V / (254 * Fs), where Ke is the braking coefficient, for passenger cars it equals one; Фс - coefficient of adhesion with a coating of 0.7 (for asphalt).
We substitute the speed of movement vehicle in km/h.
It turns out that the braking distance is 20 meters for a speed of 60 km / h, (for ideal conditions), if the braking is sharp and without skidding.
Braking distance on the surface: snow, ice, wet asphalt
BMW cars on trial
The friction coefficient helps to indicate the length of the stopping distance at different road conditions. Odds for different road surfaces:
- Dry asphalt - 0.7
- Wet asphalt - 0.4
- Rolled snow - 0.2
Let's try to substitute these values into the formulas, and find the values of the braking distance for the road surface at different times of the year and under different weather conditions:
- Wet asphalt - 35.4 meters
- Rolled snow - 70.8 meters
- Ice - 141.6 meters
It turns out that on ice the length of the braking distance is practically seven times higher relative to dry asphalt (as well as the substituted factor). The braking distance is affected by the quality winter tires, physical properties.
Testing has shown that with the ABS system stopping way is significantly reduced, but still, in ice and snow, ABS does not affect, but rather worsens braking efficiency when compared with a braking system without ABS. However, in ABS, to a large extent, everything depends on the settings and the presence of a brake force distribution system (EBD).
The advantage of ABS in winter time - full control over the control of the car, which minimizes the occurrence of uncontrolled skidding when braking. The principle of operation of ABS is similar to the performance of stepped braking on vehicles without ABS.
The ABS system reduces the stopping distance by: dry and wet pavement, packed gravel, marking.
On ice and packed snow, the use of ABS increases the braking distance by 15 - 30 meters, but allows you to maintain control over the car, without taking the car into a skid. This fact should be taken into account.
How to brake on a motorcycle?
Correctly braking on a motorcycle is a rather difficult task. Can be braked rear wheel, front, or two, skid or engine. At improper braking on high speeds you can lose your balance. In order to calculate the braking distance of a motorcycle at 60 km / h, the data is also substituted into the formula. Considering at the same time a different braking coefficient and coefficient of friction.
Braking distance of motorcycles
- Dry asphalt: 23 - 33 meters
- Wet asphalt: 35 - 46 meters
- Mud and snow: 70 - 95 meters
- Ice: 95 - 128 meters
The second indicator is the braking distance when the motorcycle is skidding.
Any vehicle owner should know and be able to calculate the length of the braking distance, and it is better to do this visually.
It should be remembered that in the event of a traffic accident along the length of the skid, which will remain on the road surface, you can determine the speed of the vehicle before colliding with an obstacle, which may indicate an excess allowable speed driver and make him the culprit of the accident.
Driving in winter is not easy. Both a novice and a professional driver with experience will agree with this. The most common advice is to do everything smoothly. Accelerate smoothly, turn smoothly and brake smoothly.
And if everything is clear with the first two points of advice, then with braking - not quite.
Nuances that many do not know a few:
ABS is not a panacea. Braking distances on winter road with ABS does not differ from the braking distance without ABS. The main advantage of the system is the predictability of the car's behavior when braking. The car does not throw to the sides, and the reaction to the actions of the steering wheel is preserved.
It is believed that intermittent braking can play the role of an analogue of ABS, on vehicles not equipped with such a system. Actually this is not true. A trembling foot on the brake pedal does nothing to reduce the braking distance and eradicate drifts and drifts. It is important to accurately capture the moment when the wheels start to lock and be able to balance on this edge. In this case, the most effective braking is achieved. This is exactly the point of intermittent braking. Simply releasing and depressing the brake pedal from the very beginning of braking does not perform this task.
Weather conditions change daily. Along with this, the nature of the road surface is also changing. As a result, wheel lock occurs in different conditions. For this reason, masters of the steering wheel are advised to check the reaction of the car to the brake application every morning before leaving. The results will surprise you.
Smooth braking also means a longer stopping distance, than braking on the verge of locking the wheels. Therefore, the main assistant when braking in winter is the distance. And not only in front, but also behind the car. 40 percent of accidents in winter are due to the fact that the driver behind failed to brake properly. The result is very different - from a cracked bumper to "chain" accidents, in which several dozen cars are involved. If you feel that the driver behind you has come too close, a couple of light strokes on the brake pedal are enough for the brake lights to come on to force the driver to increase the distance.
In conclusion, a few words about tires. main reason the fact that some drivers drive several seasons on studded without losing studs, while others on the same tires lose almost all studs during the season - this is precisely the difference in braking style. The rules described above apply not only to ice or snow. Careful drivers use them in winter and on asphalt. As a result, the spikes remain in place, and winter tires last for several seasons.
Master rally drivers advise you to practice braking technique on a free site a couple of times before starting active winter trips. Feeling the edge of wheel blocking and learning to control it, you will save not only tires, but also your own nerves and become much more confident on the winter road.
Unlike most of ours, this one is not comparative, but research. The task is to understand the behavior of tires at different temperatures. All the results obtained are valid only for the coating on which the tests were carried out - this is coarse-grained asphalt with a high coefficient of adhesion (about 0.8).
Making plans
For testing, we selected nine sets of summer tires with a dimension of 205/55 R16. As a quantity characterizing the grip properties of tires, we will use the braking distance.
The idea is this. We will start testing on the hottest days, when the air warms up to 30 ºС. Then you need to catch the decrease in temperature, repeating measurements at intervals of 10-15º in descending order - up to +5 ... + 7 ºС. It is this average daily temperature (+6 ºС) tire manufacturers they call it when in the fall you need to switch from summer tires to winter tires, and in the spring - respectively, vice versa.In addition, it is necessary to connect three winter ones to the comparison in order to compare with summer ones. But we will test them at a temperature not higher than +10 ... +15 ºС, so as not to be erased in the heat to the cord.
In autumn, you can grab frosty days when the air and asphalt have a negative temperature. The main thing is that the asphalt is dry, and the weather conditions exclude the appearance of moisture or ice on it.
We will look for an answer to the question: is it really so great and so dangerous to increase the braking distance with a drop in air temperature and, accordingly, asphalt, as tire manufacturers claim?
test subjects
The main team included the winners of our tests - Pirelli Cinturato P7 Blue (2015) and Nokian Hakka Green 2(). Added the top Continental ContiPremiumContact 5 and the novelty of the rapidly progressing company Hankook - summer tires Ventus Prime 3. Medium price segment present Toyo Proxes CF2 and Nitto NT830 Japanese made. In contrast to the top-end tires, inexpensive Belarusian tires Belshina Artmotion Bel‑263, domestic Cordiant Sport 3 and Chinese Triangle Sportex TSH11 were taken.The basis of the "winter" team was made up of clutches of the "Scandinavian" direction - these are the winners of our past Continental ContiVikingContact 6 and Nokian Hakkapeliitta R2. This “soft” pair was diluted with the tougher Nokian WR D2 tires, oriented towards warm Eastern European winters.
Brake!
The tests were carried out at the AvtoVAZ test site in the Samara region in the summer and autumn of 2016 on a hatchback.
In order not to erase the tread by repeated braking (even with ABS, the rubber wears out quite intensively), we reduced the braking start speed for summer tires on dry pavement from our standard 100 km/h to 80 km/h.
All tests were carried out on the same section of the road, on the same car and with the same "leg", that is, the driver. The brake "track" before each temperature block of measurements was cleaned by twenty-fold braking on non-recording tires. On the tested tires in each block of measurements, we braked six times, not forgetting to cool the brakes in between.
The final graphs for each tire were built according to the actual asphalt temperatures at the time of the measurements - for greater accuracy.
Dependence of braking distance on asphalt temperature
We were forced to skip tests at temperatures of +25 ... +30 ºС due to a sharp drop in temperature. The lines connecting the measurement points on the graph are conditional, since we have reliable data only at these points.
in a frying pan
The first measurements began at the end of July last year, when the air warmed up to 30–35º. A light haze in the sky did not allow the asphalt to heat up to fifty. Temperature Range coating ranged from 41 to 48º: you can’t fry scrambled eggs, but warming them up is easy!
The average stopping distance is 26.5 meters. The spread of results among the nine participants was 3.5 meters, or 13.2%. It is noteworthy that the results crowded into three rather dense groups. Three leaders - Continental, Pirelli and Hankook - showed the result from 24.8 to 25.5 meters. Almost a meter behind them was the “average” group of four tires: from 26.4 to 27.2 meters. And the last ones lost the same number - Belshina and Nitto with the results of 28.0 and 28.3 meters.
Comfortable
The heat dragged on for more than half a month, and then it got colder, so we were forced to carry out the following measurements at an air temperature of +12.5 to +14.5 ºС.
On the other hand, due to dense clouds, the temperature of the asphalt became more stable: +17…+18 ºС. Unfortunately, we jumped over the asphalt temperature point of +30 ºС, but an open-air polygon is not a climatic chamber, you cannot set the desired air temperature.
This time the results were tighter. The average stopping distance was reduced to 25.5 meters, and the spread of results was reduced to 2.5 meters, which is 9.3%. The top three remained unchanged, but a rearrangement took place within it: the leading Continental tires improved their result by 0.6 meters, and Hankook, having won back one meter, forced out Pirelli from the second place.
By evening, the temperature of the asphalt and the air decreased, but not critically. And we introduced an additional composition into the game - winter tires.
Their results, as expected, are weaker than those of summer. To stop from 80 km / h, the "Europeans" needed a distance of 29.1 m, and the "Scandinavians" - 30.4 m. The first lost almost 3.5 meters, or 14.1%, the second - as much as 5 meters or 19.2%.
Freshly
The next temperature point is the boundary one. The first cold measurements were carried out on winter tires. The air temperature fluctuated from two to three degrees Celsius, and the asphalt was practically the same: +2.2…+3.2 ºС.
"European" winter Nokian tires The WR D2 took 28.1 meters to brake (a meter less than in warmer weather), while the Scandinavians needed 29 meters (almost a meter and a half better).
While the turn came to summer tires, the sun rose and warmed the air up to +3.5…+6.0 ºС. The asphalt warmed up a little more - up to +3.8 ... + 8.4 ºС. summer tires practically did not change compared to previous measurements: 25.6 meters. But the results were even more heaped - the spread decreased to 2.2 meters, or 8.6%.
Continental gained another 0.1 meters and continued to lead with a significant lead (one meter) from the nearest rival. His example was followed by three more contestants, who improved their performance - Belshina, Cordiant and Nitto. All braking distances were reduced by 0.6 meters. Toyo "remained with its own", keeping the coupling properties unchanged. On the other tires, the braking distance of the Golf has increased - on Nokian, Pirelli, Triangle by 0.3–0.4 meters, and on Hankuk by as much as 1.3 meters.
What is the intermediate conclusion? Winter tires turned out to be sensitive to asphalt cooling to their own “maximum recommended” temperatures - having entered a comfortable temperature zone, they reduced the braking distance by a meter and a half. And now winter "Europeans" lose only 2.5 meters to summer tires (the difference is 9.8%), and "Scandinavians" - a meter more (13.3%).
frosty
The summer testing phase is over. Now we check how much the grip of summer tires deteriorates in cold weather. We catch a dry frosty day when the thermometer shows a steady minus. Naturally, there should not be a hint of ice on the pavement.
Like last time, skip ahead. They got an air temperature of -7.5 ... -8.5 ºС, and the asphalt temperature ranged from -7.3 to -9.7 ºС. The results surprised by the fact that they practically do not differ (deviations - only from 0.1 to 0.4 m) from the previous ones obtained with a slight plus.
Summer tires had a chance to slow down at air temperatures from -4 to -6.5 ºС, the asphalt was the same temperature. The average stopping distance increased by an average of one meter - up to 26.5 meters. And the spread of results was 2.6 meters, or 9.8%, - a little more than in warm weather.
Although the braking distance on the Conti has grown by 0.7 meters, these tires are still in first place. Moved to second place Nitto tires, while Hankook regained the third position.
The gap between summer and winter tires has decreased even more noticeably (by a whole meter), and this is solely due to the deterioration of traction summer tires. The difference between "summer" and winter "Europeans" was only 6.4%, and with "Scandinavians" - 9.8%.
Effect of coating temperature on braking performance
Summer tires |
||||
| Asphalt temperature, ⁰C | 6,1…-4,2 | 3,8…+8,4 | 16,8…+17,8 | 41,3…+47,9 |
| Air temperature, ⁰C | 6,5…-4,0 | 3,5…+6,0 | 12,5…+14,5 | 30,5…+35,5 |
| Belshina Artmotion Bel-262 | 26,2 | 26,8 | 28,0 |
|
| 24,8 | 24,1 | 24,2 | 24,8 |
|
| Cordiant Sport 3 | 27,4 | 25,8 | 26,2 | 26,4 |
| Hankook Ventus Prime 3 | 26,1 | 25,8 | 24,5 | 25,5 |
| Nitto NT830 | 26,0 | 25,6 | 26,2 | 28,3 |
| Nokian Hakka Green 2 | 26,7 | 25,8 | 25,5 | 26,6 |
| Pirelli Cinturato P7 Blue | 26,6 | 25,1 | 24,8 | 25,0 |
| Toyo Proxes CF2 | 26,8 | 26,3 | 26,3 | 27,2 |
| Triangle Sportex TSH11 | 27,0 | 25,7 | 25,3 | 27,0 |
| Minimum value | 24,8 | 24,1 | 24,2 | 24,8 |
| Maximum value | 27,4 | 26,3 | 26,8 | 28,3 |
| Mean value of results | 26,5 | 25,6 | 25,5 | 26,5 |
| Scatter of results | ||||
Winter friction tires |
|||
| Asphalt temperature, ⁰C | 9,7…-7,3 | 2,2…+3,2 | 12,7…+14,8 |
| Air temperature, ⁰C | 8,5…-7,5 | 2,0…+3,0 | 9,5…+10,5 |
| Braking distance (80–5 km/h), m |
|||
| Continental ContiVikingContact 6 ("Scandinavians") | 28,7 | 28,9 | 29,6 |
| Nokian Hakkapeliitta R2 ("Scandinavians") | 29,5 | 29,1 | 31,2 |
| Nokian WR D2 ("Europeans") | 28,2 | 28,1 | 29,1 |
| "Europeans": the average value of the results | 28.2 (worse than summer by 6.4%) | 28.1 (worse than summer by 9.8%) | 29.1 (worse than summer by 14.1%) |
| "Scandinavians": the average value of the results | 29.1 (worse than summer by 9.8%) | 29.0 (worse than summer by 13.3%) | 30.4 (worse than summer by 19.2%) |
What is the result?
As we have seen, none of the tested summer tires demonstrated the stability of grip properties at various, even positive, asphalt temperatures. Almost half of the tested tires have a temperature point of maximum grip - from +17 to +18 ºС, for the other half - from +4 to +8 ºС. In addition, as the temperature of the asphalt rises and falls from the temperature point of maximum adhesion, the braking distance of any summer tire increases. It is noteworthy that the braking distance at the maximum (+45 ºС) and minimum (-6 ºС) operating temperatures are close, which means that the adhesion coefficients at these temperatures are also close.
winter clutch friction tires on dry pavement worse than summer. At asphalt temperatures from -10 to -4 ºС, the difference in stopping distance is 6–7% for Europeans and 10% for softer Scandinavians. And with an increase in asphalt temperature to +13 ... +18 ºС, the difference almost doubles - up to 14 and 19%, respectively.
And here is the second very important conclusion. If in spring the average daily asphalt temperature is positive, and the daytime temperature exceeds +5 ºС, this is a signal that it is time to change into summer tires. In autumn, when switching from summer to winter non-studded tires, be prepared that the grip properties of winter friction clutches on dry asphalt will be worse by 6-10% even at an asphalt temperature of no higher than +5 ºС. Therefore, it is not dangerous to use summer tires at near-zero asphalt temperatures, but only in one case - if the road is dry!
In addition, we have identified - or, to be more precise, confirmed - another interesting fact. In order to fully compare the grip properties of tires, it is advisable to carry out tests at different temperatures. Indeed, the results of tests carried out at various temperatures(even on the same asphalt) can vary significantly. Although miracles do not happen: the leading tires retain their positions, the outsiders also.
And again we repeat the old truth: . In summer you need to ride on summer ones, in winter - on winter ones. There is no third.
Recommendations for the use of tested summer tires based on the nature of the change in traction properties depending on the temperature of the asphalt
| In cold regions | For light frosts* | in hot regions |
|
| Belshina Artmotion Bel-263 | Yes | Yes | doubtful |
| Continental ContiPremiumContact 5 | Yes | Yes | Yes |
| Cordiant Sport 3 | Yes | doubtful | Yes |
| Hankook Ventus Prime 3 | carefully | doubtful | Yes |
| Nokian Hakka Green 2 | Yes | carefully | Yes |
| Nitto NT830 | Yes | Yes | |
| Pirelli Cinturato P7 Blue | Yes | doubtful | Yes |
| Toyo Proxes CF2 | Yes | Yes | Yes |
| Triangle Sportex TSH11 | Yes | doubtful | carefully |
*On dry pavement without a hint of icing.
Everything you need to know about tires and seasonal changeovers can be found in a selection of publications including tire tests"Driving" (according to).
We express our gratitude to the tire manufacturing companies that provided their products for testing, as well as to the employees of the AVTOVAZ test site and the Togliatti company Shintorg for technical support.
Continental took part in a winter road safety event hosted by Continental official dealer LLC "Exclusive" in the city of St. Petersburg. We support our partner in the pursuit once again warn motorists of the approach winter season and tell them about the features of the operation of the car during its period.
“Safety on a winter road largely depends on the timely change of summer tires to winter ones, as well as on the tread height of used winter tires,” says Dmitry Kraev, Head of Customer Service at ContinentalTires RUS LLC.
Comparison of braking distances of summer and winter tires
It should be recalled that already at temperatures below +7 C, summer tires do not demonstrate the proper level of adhesion to the road surface, which means that they must be changed to winter counterparts in a timely manner. The German concern Continental conducted a large-scale study of the behavior of summer and winter tires on a snowy road, comparisons were made at a speed of 50 km / h. According to these measurements, summer tires brake to a complete stop of the vehicle 31 meters later than their winter analogues, while the residual speed, at the moment of braking of winter tires, for summer tires is 39 km / h, which carries a serious danger for participants traffic.
Dependence of braking distance on tread depth
In addition to the timely change of tires, an important factor affecting the level of road safety on a winter road is the remaining tread depth of winter tires. Many motorists, especially in difficult conditions economic situation, do not follow technical condition winter tires. Taking into account the results of the measurements mentioned above, we can conclude that when braking from a speed of 50 km/h on a snowy road, the difference between new winter tires and their counterparts with a tread depth of 4 mm is 14 meters, with a residual speed of 27.9 km/h , if we take for comparison an analog with a tread depth of 1.6 mm, then its braking distance will be 26 meters longer, and the residual speed will be 33.8 km / h. These results are striking in their significant values even at such a relatively low speed of 50 km/h.
Tire features for the "European winter"
Not many motorists know that there are 3, and not 2, as is commonly believed, types of winter tires: studded, friction and the so-called "European winter". Winter tires for mild European winters demonstrate weaker performance on snow and ice, as well as at temperatures below -10 C, in contrast to their non-studded counterparts, widely used in the Russian Federation and Scandinavian countries. Some motorists do not know this fact and choose non-studded winter tires with a speed index higher than the T value (190 km / h) in the hope of best quality, in fact, they purchase tires for a mild European winter. We believe that tires "European winter" should be used in the southern regions of the Russian Federation, in the rest of Russia it is necessary to install either studded tires or friction tires for harsh winter conditions. You can visually distinguish between two winter studless tires by the angle that the tread and sidewall form. If on European counterparts it is sloping, then on typical friction winter tires it is sharp. The difference in performance between these 3 types of tires was beautifully described in the 19th issue of 2014, Auto Review magazine.
In the product line German concern Continental examples of a studded tire are the Continental IceContact 2, non-studded for harsh winter conditions the Continental ContiVikingContact 6, and "European winter" the Continental WinterContactTS 850 P.
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Stopping distance is the distance it takes for a car to come to a complete stop from the moment the braking system starts working.
In everyday life, this term is often confused with stopping distance, but braking and stopping distances are different concepts. In the latter case, the distance that has elapsed since the driver realized the need to brake to a speed of 0 km/h is taken into account. The braking distance is part of the stopping distance. 
What does braking distance depend on?
The indicator under consideration is not a constant value and may vary for a number of reasons. All factors affecting the braking path can be divided into two large groups: driver-dependent and driver-independent. Among the reasons that do not depend on the person behind the wheel include:
- road condition;
- weather.
It is easy to guess that in rain, snow or ice, the distance it takes to stop a car will be greater than on dry pavement. Braking will be long and when driving on smooth asphalt, in which stone chips have not been added. Here, the wheels have nothing to catch on, unlike rough surfaces.
Note: It is worth noting that poor quality road (pits, potholes) does not increase the distance required to stop. Here the human factor plays a role. Trying to save the suspension, drivers rarely develop high speed on such roads. Accordingly, the braking path is minimal here.
Factors depending on the driver or car owner:
- the state of the brakes;
- system device;
- type of tires;
- vehicle load;
- movement speed.
The fact that the length of the braking distance of the car directly depends on the health of the braking system does not require proof. A car with a broken brake circuit or worn pads will never stop as quickly as a serviceable vehicle. 
A lot depends on the design of the brake units. Modern machines equipped with rear disc brakes and braking assistance systems, have much better grip with the road and a short braking segment.
In turn, the presence of EBD with ABS does not always contribute to reducing the distance required to stop. On dry hard surfaces, where wheel lockup occurs only under very heavy braking, the system really shortens the braking distance. However, on bare ice, "smart" electronic assistant begins to lose braking force even with light pressure on the brake pedal. At the same time, the car retains controllability, but its braking path increases significantly.
What determines the rate of deceleration? Of course, the type of tires. So, on bare, albeit frozen asphalt, as well as in snow porridge, the so-called. "Velcro" - winter tires not equipped with spikes. In turn, in ice and on snowy roads the most effective is studded "rubber".
An important factor influencing the size of the stopping distance is the speed and workload of the machine.
It is clear that a lightweight car at a speed of 60 km / h will stop faster than a truck loaded to capacity and moving at a speed of 80-100 km / h. The latter will not be allowed to stop quickly, too high for him speed and inertia.
When and how is freezing
Calculation of the braking distance may be required in the following cases:
- technical testing of the vehicle;
- checking the capabilities of the machine after finalizing the brakes;
- forensic examination.
As a rule, when calculating, the formula S \u003d Ke * V * V / (254 * Fs) is used. Here S is the stopping distance; Ke - braking coefficient; V₀ is the speed at the start of deceleration; Фс is the adhesion coefficient with the coating.
The coefficient of adhesion to the road varies depending on the condition of the pavement and is determined from the following table:
| Road condition | Fs |
|---|---|
| Dry | 0.7 |
| Wet | 0.4 |
| Snow | 0.2 |
| Ice | 0.1 |
The Ke coefficient is a static value and is equal to one for all the most common passenger vehicles.
Example: how to calculate the stopping distance of a car when the speedometer shows 60 km/h in the rain? Given: speed 60 km/h, braking coefficient - 1, adhesion coefficient - 0.4. We consider: 1*60*60/(254*0.4). As a result, we get the figure 35.4, which is the length of the braking distance in meters.
The table shows how many meters the car will continue to move until it comes to a complete stop. It should be borne in mind that no other indicators are taken into account (turns, potholes on the road, oncoming traffic, etc.). It is doubtful that in real conditions on an icy road, a car will be able to slip a kilometer and not meet a pole or a bump stop.
| Speed | Dry | Rain | Snow | Ice |
|---|---|---|---|---|
| km/h | meters | |||
| 60 | 20,2 | 35,4 | 70,8 | 141,7 |
| 70 | 27,5 | 48,2 | 96,4 | 192,9 |
| 80 | 35,9 | 62,9 | 125,9 | 251,9 |
| 90 | 45,5 | 79,7 | 159,4 | 318,8 |
| 100 | 56,2 | 98,4 | 196,8 | 393,7 |
| 110 | 68 | 119 | 238,1 | 476,3 |
| 120 | 80,9 | 141,7 | 283,4 | 566,9 |
| 130 | 95 | 166,3 | 332,6 | 665,3 |
| 140 | 110,2 | 192,9 | 385,8 | 771,6 |
| 150 | 126,5 | 221,4 | 442,9 | 885,8 |
| 160 | 143,9 | 251,9 | 503,9 | 1007,8 |
| 170 | 162,5 | 284,4 | 568,8 | 1137,7 |
| 180 | 182,2 | 318,8 | 637,7 | 1275,5 |
| 190 | 203 | 355,3 | 710,6 | 1421,2 |
| 200 | 224,9 | 393,7 | 787,4 | 1574,8 |
We found an interesting calculator that not only calculates the indicator depending on the speed and road conditions, but also clearly shows the whole process. Located .
How to increase the intensity of the slowdown
From the foregoing, it became clear what is called the braking distance and what this indicator depends on. However, is it possible to reduce the distance required to stop the car? Maybe! There are two ways to do this - behavioral and technical. Ideally, if the driver combines both methods.
- Behavioral method - you can shorten the braking distance if you choose a low speed on slippery and wet roads, take into account the degree of workload of the car, correctly calculate the braking capabilities of the car depending on its condition and model year. So, the "Moskvich" of 1985 development will not be able to slow down as effectively as the modern " Hyundai Solaris”, not to mention more respectable and technologically advanced models.
- The technical method is a method of enhancing braking capabilities based on increasing the power of the braking system and using auxiliary mechanisms. Manufacturers of modern vehicles are actively using such methods to improve brakes, equipping their products anti-lock systems, braking assistance systems, using more efficient brake discs, pads.
It should be remembered that reducing the time required to stop is one of the ways to ensure the safety of the trip. Therefore, every driver must constantly monitor the technical condition of his " iron horse", in a timely manner to maintain and repair the braking system. In addition, it is important to choose the speed of movement taking into account the environment: time of day, road conditions, car model, and so on.
