These concepts are inseparable from each other. Complex road conditions is one of the factors directly affecting traffic safety.
Road conditions include both the quality of the road surface itself (pits, bumps, potholes, markings), and weather conditions, as well as terrain (for example, driving along a serpentine in the mountains). In this article, we will briefly dwell on the intricacies of driving a car in most difficult road conditions.
Driving a car in difficult road conditions affects all drivers in one way or another. Despite the fact that most of the population lives in cities, the urban road network is far from ideal. Therefore, even in major cities difficult meteorological conditions and traditionally “sudden” winter
As required traffic rules driver obligated to comply necessary measures security, to avoid emergencies up to a complete stop of the vehicle.
In the same time, road services are obliged to respond in time to changes in weather conditions, to the quality of the road surface and take all measures to ensure accident-free traffic.
In practice, however, the picture appears somewhat different.
Under difficult road conditions, traffic safety primarily depends on the skill of the driver, his attentiveness, combined with caution.
Compliance with simple rules will reduce the likelihood of an accident by several times.
Driving in ice
One of the most dangerous road conditions is ice. It is characterized by a vitreous coating on the road, which consists of ice, dust and water. Due to the special state of water at sub-zero temperatures, any object on ice easily slides along an arbitrary trajectory. The car, getting on an icy road surface, almost always loses control due to insufficient grip. Conditions are especially dangerous: ice + fresh snow, ice + water. With ice, the undoubted advantages will be:
High-quality spikes and qualified spikes;
Anti-lock braking system ABS ;
Low speed of movement;
Four-wheel drive;
Smooth terrain.
Ice also includes snow run-up, which has a similar structure and low coefficient of adhesion.
Driving in icy conditions:
Starting is smooth, without jerks in the forward direction;
Braking is smooth, without disengaging the clutch, if necessary, switching to lower gears;
Using intermittent braking reception (For vehicles without ABS);
Do not spin the engine, "gas" smoothly and gradually. The same applies to gear changes. Any jerks and regassing are almost guaranteed to lead to the failure of the drive wheels and the skidding of the car.
WITH mechanical box, gear shifting should be as fast as possible, with ideally matched engine speeds;
Driving uphill should be done at a higher engine speed, approximately + 20% of the nominal value. This will allow you to switch more accurately, preventing the wheels from slipping.
If you have already stalled, you should rock the car. In no case do not "gas"! The wheel will dig into the ice very quickly, and it will be impossible to start without help. Critical periods are spring and autumn, the time of day is morning and evening.
Driving in the snow
It is also quite common in our country. It entails two main dangers - a deterioration in visibility and a change in traction. The first is very dangerous, especially at night. The headlights are instantly scattered by falling snowflakes, the beams of the headlights become shapeless and the road surface is practically not illuminated. With heavy snowfall at night, the effect of self-dazzle is possible - when a light spot worsens visibility to almost zero.
Snowfall threatens to reduce the effectiveness of traction. For this reason, it is worth reducing the speed to the maximum possible. In advance, at the first sign of snowfall, check the operation of the wipers and washer.
Driving style is similar to driving in icy conditions. It is very dangerous to brake on a smooth and / or uneven surface - on cobblestone pavements, tram tracks, road markings etc. Almost always, this is fraught with loss of control.
It should be noted that snow almost always quickly clogs light optics. Not surprisingly, after half an hour of driving, your headlights may no longer illuminate the path, and brake lights and direction indicators will be completely invisible! It is very dangerous!
The heater must be in good working order - during a snowfall, the windows quickly fog up and you can almost instantly “go blind”.
We pass snow drifts and even small snowdrifts slowly so as not to get hit in the bumper.
In winter, it is useful to have belts or snow chains - this can help out in a difficult situation. Take care also of a shovel and a good cable.
Driving in the rain
Rain, downpour. There are also two main dangers - a decrease in visibility and a change in grip. Rain is somewhat easier to bear than snowfall, at least because it does not, as a rule, cause a sharp change in air temperature and does not “clog” lighting fixtures. However, there are unpleasant "surprises" in the rain. He tends to fill holes of considerable size and depth, which become indistinguishable from an ordinary puddle. Getting into such a hole with a wheel is at least unpleasant, and at most it threatens with a torn suspension and tipping over.
On an unfamiliar road, you should behave very carefully and do not exceed the speed limit. Firstly, you can get into the already mentioned hole “disguised” by water. Secondly, you can "grab" hydroplaning. This is a very unpleasant effect, which is characterized by a complete or partial loss of contact between the wheel and the road. The physics of the phenomenon is simple. At a certain speed, the wheel can no longer “squeeze out” a layer of water from under itself in time and begins to literally swim. Grip with pavement at the same time, zero and the car almost always loses control. And this is a potential disaster.
Due to the fact that aquaplaning occurs at a sufficient high speed, often drivers encounter it on country roads or city highways. What does it mean to lose control of a car in a busy passing and oncoming traffic, we believe, it is not necessary to explain. In addition, the same aquaplaning makes it impossible to quickly and effectively brake. And if, moreover, half of the wheels roll on hard asphalt, and the other half “floats”? Pressing the brake pedal almost guarantees instant skidding.
If you get into a puddle, you should not change the trajectory of movement and brake sharply. The best way out is to smoothly release the gas while braking.
Driving in fog
Fog is an intermediate in complexity phenomenon between snowfall and downpour, which, however, has its own characteristics. Fog can make visibility zero, meaning you can't see anything but the hood of your car. Fog is often called a "deceiver" or "illusion generator" - it absorbs light and sounds well. Moreover, it can distort sounds, for example, illusoryly bringing distant sounds closer, and significantly moving away close ones. Morning or sudden fog is especially dangerous, usually in areas of lakes and rivers. Entering the fog can be sudden for the driver, which is fraught with severe accidents.
When approaching the fog, we must reduce the speed to almost zero, since it is impossible to understand and feel the density of the fog at a distance. Be sure to turn on all lights. Some experts recommend opening windows and periodically serving sound signals. If visibility is zero, it is best not to continue driving and find an opportunity to pull off the road altogether. Fog is not a very long phenomenon, however, it is extremely dangerous. Every year we see terrible accidents not only on domestic routes, but also on foreign autobahns with dozens, if not hundreds of broken cars and crippled drivers. A good helper will be high-quality and properly adjusted fog lights.
Riding at night
Tough driving period. This is especially true for unlit country roads. Despite the fact that traffic intensity drops tenfold at night, the probability of getting into an accident, on the contrary, increases significantly. Attention weakens, the usual mode of wakefulness and sleep is disturbed,
The main dangers of night driving:
insufficient illumination,
Increased fatigue and tiredness
Danger of falling asleep while driving
Blinding by oncoming and passing traffic,
Distortion of visibility, biased assessment of the distance, color and structure of objects.
There are rules and restrictions for driving at night:
Always reduce your speed to the minimum, especially in winter and on unfamiliar roads.
Never look at oncoming headlights! If you accidentally “caught” the beam, immediately slow down and stop smoothly without changing lanes.
Look carefully at the edge. This will allow you not to move off the surface (in the absence of markings) and in time to notice a car standing on the side of the road or a walking pedestrian.
If an oncoming car blinds you, blink it several times high beam. The oncoming vehicle should blink in response. If this does not happen, the driver of the oncoming car did not understand you or simply does not notice your signals. There are three options here: stop and skip, continue driving with low beam, continue driving, but turning on the high beam. Each scenario has its supporters and opponents, decide for yourself. Our recommendation is to slow down to a stop.
Turns are slow, especially in unfamiliar terrain. At night, without bright markings, it is very difficult to assess the curvature of the turns, so it's not worth the risk.
The most dangerous time is around 4 am. Be sure to ask someone to take over for you, and if you're the only driver, it's worth getting some sleep. Find a safe place and get at least half an hour of sleep. Usually this period is enough to restore strength.
Finally, given the beginning of the holiday season, some recommendations for driving in the mountains.
Mountain serpentines
Sometimes, for example, when traveling south, an unprepared driver may encounter mountain roads. Management in the mountains also has its own characteristics. The main thing is the observance of safety regulations. Common accidents on mountain roads are run-offs, overtaking collisions on hills, speeding on descents, and the associated loss of control with a “bounce” off the motorway or a head-on collision.
The main rule is to slow down. If the serpentine is high enough, unaccustomed oxygen starvation can affect the perception of speed and distance, and provoke illusions. If you have no experience of driving in mountainous areas, it is better to avoid overtaking - this is quite dangerous. Slowing down is also necessary because mountain turns are usually very steep.
If you need to stop, try to avoid it on the rise. Always stop on a downhill slope, regardless of the amount of ascent or descent.
Stock up on recoil wedges in advance, or at least a couple of flat cobblestones - this may be needed.
stock up brake fluid and antifreeze. On mountain roads, brakes often fail, and cars boil. This is especially critical in the summer heat.
Avoid shifting gears on a hill.
If you notice a slow moving car ahead, do not approach it, continuing to move at a distance. This is necessary in case of loss of control topics.
If there is a visible obstacle on the rise, switch to a lower gear in advance, but do not twist the engine - you will get overheated very quickly!
Consider " dead zones”, especially for heavy trucks.
Traffic safety in difficult road conditions depends primarily on the driver himself, his skill, caution, attention and a sensible choice of driving style.
In conclusion, I suggest reading the blog article: what directly affects both traffic safety and driving in difficult road conditions.
In this article, we will consider the features of driving a car in difficult road conditions, more precisely, in conditions limited visibility.
What conditions for driving on the roads can be classified as difficult? For example, a clear day, visibility - to the horizon, few cars on the road, no pedestrians. This normal conditions or complex? Or, the same day, but there is heavy traffic and a lot of heavy vehicles on the road.
Or, for example, all this happens either during rain or fog. Or, worse, in the snow. It is impossible to answer unambiguously. Moreover, the usual situation for experienced driver may seem difficult for someone who has recently got behind the wheel. And that's okay.
Difficult road conditions are, in general, a combination of factors that may result in or insufficient visibility, or vehicle controllability deteriorates.
This may include
- weather conditions (rain, fog, snowfall, bright sun, ice);
- traffic conditions (oversized vehicles: trucks, tractors with semi-trailers, buses; intersections and roadside areas with limited visibility; closed turns, climbs; objects near the road: trees, bushes, standing transport, buildings, etc.)
- in fact, the car itself (everything inside the cabin can interfere with the view, as well as the performance of individual components, such as a windshield washer, wiper, interior heater, glass heater, etc.).
All of these factors have one thing in common: in such situations, different reasons always hard to see traffic situation, i.e. we can safely say that visibility is limited or insufficient. These two phrases have different definitions(they need to be remembered for solving), but in life, in relation to traffic situations, It is the same.
Another nuisance when it rains is a puddle. Its insidiousness lies in the fact that it can turn out to be both shallow and deep, hiding a hole under it, all sorts of bumps, stones, etc. And the closer this puddle is to the side of the road, the greater the layer of dirt on its bottom. In no case do not try to overcome a puddle at high speed - you risk losing control of the steering. In addition, water may enter engine compartment, and this is fraught with problems in the electrics and electronics, up to the point that the engine can stall.
Before you enter this puddle, you must slow down in advance. And after leaving the puddle, especially if it turned out to be deep, you need to remember to check the brakes and, if necessary, dry brake pads by pressing the brake pedal several times while driving.
When it rains often and heavily, it seems that everything around seems to be immersed in fog. If this happens at night, then visibility is further complicated by the reflection of oncoming headlights from the wet road. You need to drive in heavy rain as carefully as when driving in fog. True, in the case of rain, properly working windshield wipers come to the rescue.
Wiper blades should fit snugly against the glass so that there are no blind spots on the surface, but they only work well on clean glass when enough rain water or washer fluid. Therefore, if on windshield there are traces of dried dirt (for example, from insects, if the bird did not miss, etc.), then it would be better to remove this dirt manually. Either with water, or with cleaners. If the brushes are worn out and do not do the job, they should be replaced.
Driving in heavy snow
When it goes dense snow, then the same feeling is created as in heavy rain - there is a white wall ahead, especially if the snow has already covered the ground and does not melt. What can be seen around? Shadows, contours, lights. Everything is in a fog. When the snow is heavy, the only thing you can see is the right side of the road, perhaps the center line will be visible, parking lights front cars, which, by the way, will periodically be lost in the snow. Visibility, again, is poor.
What can be done to improve visibility by choosing traffic tactics? Again - slow down! Move so that it is possible in case of danger to stop within your sight. Increase your distance. Remember that in conditions of limited visibility, you need more time and space to make any maneuver and stop.
If visibility is so limited that you are not able to correctly determine the location of other road users on the roadway, it is best not to risk putting yourself and others at risk. It's better to leave the road, finding for this comfortable spot, and wait there to improve visibility conditions. Nothing urgent is worth the risk. And when you stop, don't forget to turn on alarm.
In the next article, we will consider the features.
Navigating a series of articles
Driving a car in adverse weather and climatic conditions
Weather and climatic conditions have a significant impact on traffic safety, especially in the autumn-winter period, when rains, snowfall and icing of the road surface significantly complicate the operation of the rolling stock and increase the likelihood of an accident. Low air temperature impairs the operation of the engine, units and vehicle components. Decreased performance battery, tire elasticity. There is a risk of water freezing and damage to the cooling system. And how many troubles the driver is given by the low coefficient of adhesion of tires to the road, limited visibility and visibility.
Peculiarities technical operation car in autumn and winter. When preparing the car for the autumn winter operation First of all, you should check technical condition and troubleshoot. in the engine, gearbox and rear axle summer grades of lubricants should be replaced with winter grades. Otherwise, apart from increased wear units may be damaged.
The main attention should be paid to the nodes and mechanisms that directly affect traffic safety. After all, the braking qualities of the car, its controllability, the possibility of an involuntary change in the direction of movement, the supply and visibility of maneuvering signals depend on them.
It should be remembered that the most minor malfunction, which does not play a significant impact on traffic safety in summer conditions, can cause a traffic accident in winter. Especially dangerous is the uneven action of the brakes of the right and left wheels of the car. Even with light braking slippery surface this failure is fraught with dangerous consequences. Therefore, when preparing for winter operation, it is necessary to check and adjust the clearances between the drums and brake shoes. Uneven wear tire tread or differential pressure during braking also cause the vehicle to pull to one side or skid.
Ice is the most dangerous. The coefficient of adhesion of the tire to the road decreases several times and is 0.1-0.2 instead of 0.6-0.8 on dry pavement. Naturally, the forces holding the car on a given trajectory decrease by the same amount. When the vehicle is driven on dry pavement, the traction reserve remains large enough to keep the vehicle from skidding even when maximum braking or traction forces are applied. It's a different matter with ice, when a little braking or pressing the accelerator pedal can lead to a skid. On slippery road operate the steering wheel, press the clutch pedal, steer throttle valve it is necessary to smoothly apply combined braking, i.e., a service brake and an engine, which increases the braking efficiency of the car, and also helps to prevent blocking of the drive wheels.
Combined braking can be performed in a constant gear or with sequential downshifts. Since the inclusion of lower gears at high frequency rotation crankshaft engine presents significant difficulties even on vehicles with a synchronized gearbox, then regassing is required to equalize the circumferential speeds of rotation of the gears involved. Since the right foot of the driver performs braking with the service brake, in order to re-gas it is necessary to temporarily stop active braking, or press the accelerator with the toe (heel) of the foot without interrupting braking with the service brake. And so that the engine does not fail, especially if downshift is turned on with a large lead in engine speed, the clutch must be engaged with some delay.
Small straight sections with ice are best driven on the move, without changing the position of the steering wheel and without braking. In no case should you give in to the reflex desire to press the brake pedal, as this can cause the car to skid.
Having determined that the car continues to move in a straight line, you should gradually reduce the engine speed and reduce the speed to safe limits. It is much more difficult to perform turns on ice. First of all, it is necessary to reduce the speed of movement in advance, using combined braking for this, then turn on desired gear and turn at low speed. It is impossible to start the car by coasting by disengaging the clutch, since when it is turned on again, a jerk in the transmission can lead to a skid. It is very dangerous, especially when turning left, to pull over to the side of the road: loose snow lying on it can cause a skid or “pull” the car into a ditch. If, nevertheless, the car has pulled over to the side of the road on one or even two sides, there is no need to rush to return it to carriageway. Frost, usually formed at the border of the carriageway and the shoulder, can cause the car to skid and turn around. Therefore, you must first reduce the speed to the required limits and only then carefully return to the roadway.
When driving on an icy road, one should not always rely on anti-slip materials that are sprinkled on the road. It often happens that the sand is not kept on the icy surface and is freely moved by the wheels of the car. Freshly fallen snow is also dangerous in ice conditions, which masks the icy coating. When braking, the snow does not roll, but moves ahead of the wheels of the car. Tire grip is reduced, and braking distances vehicle is greatly increased.
Particular care must be taken when driving uphill and downhill during icy conditions. First of all, it is important to correctly determine the gear in which you can overcome the slope without shifting. You should switch to this gear in advance, before the start of the ascent. If, on the selected gear, it is necessary to switch to a lower gear as quickly as possible, gradually increasing the engine speed in order to prevent the drive wheels from slipping.
For long steep descents” which often end in a narrowing of the roadway, it is necessary to turn on the third or even second gear in advance. During the descent, you must not use the coast, as the car may develop too high a speed and become uncontrollable. On a descent, intermittent braking should be applied due to the fact that the temporary termination of the brake mechanisms allows you to keep the optimal temperature regime service brake of the car, and hence its effectiveness.
When starting off on a slippery surface, the drive wheels must not be allowed to slip. Therefore, you need to touch on more high gear and at minimum engine speed, very smoothly releasing the clutch pedal. This will reduce the traction moment on the drive wheels and thereby prevent them from slipping.
Overtaking during ice is an undesirable maneuver. If, nevertheless, it is impossible to do without overtaking, it is necessary to change lanes very smoothly into the next lane, after making sure that this maneuver does not interfere with other road users. It is also necessary to return to your lane after overtaking very smoothly in order to prevent skidding.
Vehicle drift. Perhaps there is no one among the drivers who has not experienced a car skid. This trouble lurks on wet pavement, and in icy conditions, and on snow covered road. Brake - and the car will skid ... It is known that with a sharp skid of the car, a transverse inertial force arises. It unequally distributes the load on the right and left tires, while the springs have a different deflection. The body warps, the stability of the car decreases. Composure, sober calculation, confident actions of the driver can prevent skidding.
Let's analyze the case correct conclusion the vehicle from skidding while overtaking, detour or turning. The car skidded, say, to the left, its rear part lost direct direction movement. As soon as the driver feels the start of a skid, he must, without disengaging the clutch, reduce the fuel supply to such a limit at which the engine transmits the minimum torque to the drive wheels. In this case, it is necessary to ensure that the car is in no case slowed down by the engine, since the increasing braking forces on the wheels only increase the skid. Simultaneously with the release of gas, smoothly turn about half a turn steering wheel towards the skid, in our case to the left. As soon as the lateral speed starts to decrease, return the steering wheel to the straight ahead position. Even if the car continues to move sideways for a while, it will gradually return to a straight line. It may happen that the car turns a little in the other direction, i.e. to the right. Such a turn must be compensated by a corresponding turn of the steering wheel to the right. After several damped oscillations, the car will take a straight position on the roadway.
It should be noted that skidding on a turn with a sufficiently high qualification of the driver can be used to facilitate maneuvers. In the initial stage of skidding, it is necessary to sharply increase the engine speed, and in the future to regulate the position of the car not only with the steering wheel, but also with gas. After the skid stops, the car will turn in the direction of exiting the corner, and you can continue to move, gradually adding gas. This method significantly speeds up the recovery of the car from a skid on a turn; it can be used only after appropriate training on flat and fairly wide horizontal ice-covered areas.
The techniques for getting the car out of a skid that occurs during braking are basically similar to the methods for getting the car out of a skid on a turn. It is only necessary to remember that in case of blocking of the wheels, it is necessary to instantly loosen the pressure on the brake pedal. This is the main rule for stopping a skid, which must be constantly remembered. And then you need to act in the same way as when skidding on a turn. In winter, ruts form on some sections of the road. When driving along it, and especially when leaving it, the possibility of a sharp skid of the car is not ruled out. You should leave the rut when there are no i others nearby Vehicle by slowing down the speed. In this case, it is necessary to slightly turn the steering wheel in the direction opposite to the exit, and then vigorously turn it towards the exit.
On a well-rolled snow-covered road, you can move at a slightly higher speed than on icy roads, however, it must be borne in mind that when driving in narrow sections, the wheels may fall into loose snow lying on the side of the road. So you need to slow down.
Driving on wet and polluted roads.
In late autumn, leaves falling from trees lying on the road surface are a great danger. Once in such a site, the driver of a car moving from high speed, if braking is necessary, it can lose control and end up in a ditch or in the oncoming lane, since the leaves under the wheels of the car can act as a lubricant, sharply reducing the coefficient of adhesion of one or more wheels. To prevent this from happening, it is necessary to assess the situation at a greater distance than on a dry road and anticipate its possible changes, which will allow you to slow down in a timely and fairly smooth manner.
In autumn and spring, the road surface is often not only wet, but also dirty due to intensive agricultural traffic. Although a wet, contaminated pavement is less dangerous than an icy one, however, it should be taken into account that the coefficient of adhesion of wheels to the road on a wet asphalt concrete pavement decreases by 1.5-2 times compared to a dry one, and dirty and oily - by 4 times. In the same ratio, the braking distance of the car also increases.
The onset of rain is especially dangerous for drivers. The first drops do not wash off, but only moisten the road dust and dried dirt, turning them into a "lubricant", which significantly reduces the effectiveness of the brakes. .Experienced driver feels the movement of the machine that after a long and heavy rain, the coefficient of adhesion increases slightly. This is the result of the slippery film being washed off the road by streams of water. In rainy weather, sections where secondary unpaved adjoin the main asphalt road are especially dangerous. Soil dirt applied by people, vehicles or livestock can play a fatal role.
Movement along wet road also dangerous in that water, falling on brake pads significantly reduces the effectiveness of the brakes. Therefore, when driving through large puddles and during heavy rain, you should periodically check the operation of the brakes while driving. If the brakes are wet, then they need to be dried by adding gas, and slowing down with your left foot. When the driver feels that the brakes have been restored, he can continue with normal driving.
Sometimes in the rain, a very dangerous phenomenon can occur - hydroplaning. Its essence lies in the fact that at a sufficiently high speed and a large thickness of the water film, a water wedge appears in the contact zone of the tires with the road, tearing off the wheels of the car from the coating. The car seems to sit on rear wheels, while the front ones are raised on a water wedge. The car stops listening to the steering wheel, although rear wheels continue to maintain traction. For this reason, the car, even in straight sections, unexpectedly finds itself on oncoming lane movement, and on curves suddenly pulls over or rolls over. A layer of water several millimeters thick causes hydroplaning at speeds over 80 km/h. That's why experienced drivers when driving through areas flooded with water, they adhere to a speed of no more than 60-60 km / h.
Hydroplaning depends on the thickness of the water film, the quality of the pavement surface, the volume of water, the presence of transverse grooves on the pavement, the tread pattern of the tire, the specific pressure in the contact zone, vertical and lateral loads.
It should be noted that hard tires modern trucks better destroy the water cushion, the effect of hydroplaning begins only at. speeds of 120-140 km / h, i.e., practically unattainable for them, and more elastic tires cars destroy the water film only at speeds up to 60-80 km/h.
Not knowing about the existence of the effect of hydroplaning, some drivers explained this state of the car (in which the brakes do not “grab”) simply by oiling the pads or poor operation of the brake drive (not pushing the working fluid).
It is difficult to teach a driver to determine the starting point of hydroplaning, but knowledge, experience, a desire to understand and find safe methods of driving a car will help in this.
wind load. In autumn, strong winds often rise. Therefore, the driver must be aware of the features of driving a car associated with wind load.
The strength of the wind is not constant either in magnitude or in direction.
The most unpleasant for the driver is a strong lateral wind load. Suffice it to say that at a wind speed of 25 m/s, an additional lateral force of about 300 kg acts on a Zhiguli car, and more than 1,600 kg on a LAZ bus. On slippery and icy surfaces high speeds motion such a force is able to move the car. A skid may begin.
Under the influence of lateral wind load, the tires deform due to their elasticity, and the car deviates from a straight path. The driver must compensate for this deviation by turning the steering wheel, and the car will remain straight, moving with the front wheels turned at some angle. With a sharp increase or decrease in wind strength, it is necessary to maintain the desired direction of movement in a timely manner, by small turns of the steering wheel. In places where a sharp gust of crosswind can deviate the vehicle from rectilinear movement, a warning sign 1.27 "Sidewind" is installed.
The main safety measure when driving on such sections of roads is to reduce the speed of movement.
| Vladimir |
Road conditions
TO category:
Driving a car
Road conditions
The driving conditions of the car are determined by road conditions, as well as the nature traffic flow and related to weather and climate factors. Road conditions have big influence on driving and driving habits. They are evaluated by geometric parameters and transport and operational characteristics of roads - engineering structures intended for traffic vehicles. The roads laid through the built-up area are streets.
The classification of roads provides for their division by regional significance and traffic intensity into the following technical categories:
I category - car roads national and republican significance with a traffic intensity of more than 7000 vehicles / day.
Category II - motor roads of the specified value with a traffic intensity of 3000-7000 vehicles / day.
Category III - highways of national and republican significance (except for I and II categories), regional or district significance with a traffic intensity of 1000-3000 vehicles / day.
Category IV - motor roads of regional or district significance (except category III), local roads with a traffic intensity of 200-1000 vehicles / day.
Category V - local roads with a traffic intensity of less than 200 vehicles / day.
The geometric parameters of the road determine its shape in the horizontal plane (in plan), as well as in sections in the vertical longitudinal and transverse planes. These parameters should ensure the movement of the car on a dry or wet clean road surface at the highest safe speed; they are established by building codes and regulations (SNIP II 60-75).
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In the horizontal plane, the road may have curved sections, the radii of curvature and the frequency of which have a great impact on traffic safety. As the radius decreases, centrifugal force, which increases the risk of skidding and rollover, so the smallest value of the curvature radii is normalized depending on the category of the road. For example, necessary security traffic on roads of category I is provided with curvature radii of at least 1000 m, in urban traffic - with minimum radii from 400 m on city highways to 125 m on local streets.
In the vertical longitudinal plane, the radius of convex curves near city streets should be in the range from 2000 to 6000 m, concave - from 500 to 1500 m, longitudinal slopes should not exceed 5 to 8 |% ;.
In the vertical transverse plane, the section of the road allows you to highlight its main elements: the carriageway, roadsides, ditches and sawn-off; the street is distinguished by the presence of sidewalks (Fig. 1).
Rice. 1. The main elements of the road: a - road lane; b - subgrade; c - roadway; g - dividing field; d-curb; e - cuvette; g - cut
All road elements, together with road devices and equipment, occupy a certain area called a road lane.
The carriageway is characterized by a gable cross profile with a slope of 1.5 to 4%, depending on the type of road surface on straight sections of roads and on curves with a radius of more than 2000 m. At radii of less than 2000 m, the curves must have turns with a cross slope of 2 to 6 %. The width of the carriageway of category I roads must be at least 15 m with four or more traffic lanes. On roads of other categories, it is usually 7.5 m with two lanes, but can be equal to 4.5 m on roads of category V.
Geometric parameters should provide visibility on city highways with visibility of the road surface at a distance of 175 m, an oncoming car - 350 m. On other roads, these visibility distances should be equal to 75 and 150 m, respectively.
The transport and operational qualities of the road are determined by the type and condition of the road surface, as well as road devices and equipment.
Types and types of pavement are used depending on the category of the road, taking into account the nature of the traffic flow, climatic and other conditions. Coatings are divided into the following groups:
- improved capital type for roads of category I, which includes cement concrete and asphalt concrete types;
- improved lightweight type for roads II, III and IV categories, which include asphalt concrete and bituminous types;
- transitional type for roads of IV and V categories, including crushed stone and gravel types;
- soil type for roads of category V, which can have types of coatings improved by local materials.
The condition of the road surface is characterized by roughness, humidity, contamination of its surface and depends on the degree of deterioration of the pavement, meteorological conditions and the quality of road maintenance. The roughness of the coating improves its grip on tires on dry and especially wet surfaces. Moisture and dirt create a kind of lubricant layer that separates the coating and the tire, dramatically reducing their coefficient of adhesion. If the thickness of this layer is less than the height of the roughness protrusions, then due to the grip of the tire with these protrusions, the friction coefficient remains almost unchanged. The tread pattern increases the traction coefficient with an increase in the depth and size of its grooves, ribs and grooves. The driving mode affects the coefficient of friction mainly in connection with the increase in speed and the nature of braking. With an increase in speed above 60 km/h, the friction coefficient decreases slightly compared to the calculated value, so that at a speed of 100 km/h this decrease is 10%:.
Increased slipperiness of the road surface causes wheel slip, reduced braking efficiency and vehicle side skid, which are responsible for about 50% of traffic accidents related to road conditions. The friction coefficient equal to 0.4 was adopted as the minimum allowable in terms of traffic safety.
Road devices are designed to improve the safety and convenience of transporting goods and passengers. These include areas for stopping and parking, bus stops, platforms and pavilions for passengers to rest and wait for buses, communication devices, lighting, protection of roads from snow and sand drifts.
Road equipment is a complex technical means traffic control and includes road signs and roadway markings, traffic lights, signs, information boards, fencing.
Weather and climatic factors change driving conditions, affecting the driver, car and road. These include temperature, humidity and air pressure, precipitation, wind, which form three periods of operation: summer, winter and transitional. Summer period it is mainly characterized by a stable average daily temperature above +15°C, winter temperatures below 0°C, spring and autumn periods are transitional, when the temperature is between the indicated values.
The driver is able to drive the vehicle with the greatest reliability at temperatures around +20°C. With increasing temperature and humidity, the reaction time of the driver increases, his fatigue accelerates. At low temperatures hypothermia and an increase in the moisture evaporation of his body may occur, which also increases fatigue.
The technical condition of the car deteriorates during the transition period and especially during winter periods: glasses and headlights are splashed with mud or snow, water gets on the brake pads, condensation forms in the pneumatic brake drive, tires lose their elasticity at low temperatures. This significantly reduces visibility, reduces visibility, worsens braking properties vehicle and increases the risk of a traffic accident.
Road conditions are most affected by weather and climatic factors, due to which the transport and operational qualities of the road change greatly. During transitional periods, the carriageway is polluted, its usable width decreases and the adhesion properties of the coating decrease, roadsides are destroyed, visibility on the road is reduced, and the visibility of road equipment elements is deteriorating. In winter, the boundaries of the subgrade of the road are smoothed out and its geometric parameters. A layer of snow forms on the road surface, and at temperatures from 0 to -3 ° C and high humidity air ice occurs, which sharply reduces the adhesion of the coating.
Improvement of the road network is the most difficult of the most important tasks state system security traffic. For high-speed and safe movement of cars, the road must have the correct geometric parameters, high-quality coating, and the necessary equipment. Roadside devices should be of an energy-absorbing or other design that reduces the severity of the consequences of collisions with vehicles.
Many of the novice motorists, and even experienced motorists, do not always know how to properly and safely drive a car in difficult road conditions, the main of which are driving in ice, heavy rain, fog (limited visibility conditions), and also, in snowfall, or on a winter road.
cornerstone safe management the car in all road conditions, and especially in difficult ones, is the good technical condition of the car, good work windshield wipers and lighting devices, as well as the appropriateness of the type of tires for the season and climatic features region.
Fog
When driving in the fog, or in conditions of limited visibility, in without fail it is necessary to reduce the speed of movement to a level that allows you to make emergency braking vehicle in front of a possible unexpected obstacle.
In addition, it is necessary to turn on additional lighting devices, or fog lights, and as an additional source of attracting attention, turn on the alarm, which will attract the attention of other road users and create an additional safety zone.
It is strongly not recommended when driving a car in conditions of limited visibility, the use of high beam headlights as a source of additional lighting, because in this case, high beam, not only impairs visibility, but also leads to increased visual fatigue of the driver of the car.
Rain
Heavy rain, makes its own adjustments to any movement, so, when driving in rainy weather, it is necessary to reduce the speed of movement and increase the distance to the car in front.
Avoid sudden lane changes, accelerations, and braking, trying to drive the car as straight as possible, and in the event of a hydroplaning effect caused by a sharp deterioration in contact car tires with the road surface, it is necessary to smoothly and gradually release the gas pedal, thus carrying out soft braking, and resuming contact of the tires with the surface.
A good solution would be to turn on additional light sources, and in case of very heavy rain and an alarm.
Ice
When driving on ice, and under conditions heavy snow, you should take into account the increased braking distance, therefore, the distance to the vehicle in front should be as large as possible.
Strictly prohibited sharp accelerations, braking and rebuilding, all these maneuvers performed in ice and snow, even on flat road, inevitably lead to a loss of adhesion to the surface, and the subsequent breakdown of the car into a skid.
The speed mode of movement must be chosen not only on the basis of overall speed traffic flow, but also taking into account the individual properties of the car, as well as the type of installed car tires.
It is necessary to carefully monitor the operation of the engine and the driving mode, while it is advisable to keep the engine speed at a level close to the beginning of the maximum engine thrust level - because in this case, with an unexpected skid, by sharply pressing the gas pedal, you can increase the engine thrust to maximum, and immediately get out of the starting skid.
