Dnepropetrovsk State University
internal affairs
Department of "Tactical and special training"
Essay
from "Automobile training"
on the topic of:
"Movement in complex weather conditions»
Completed:
cadet of 301 study group
police officer
Korzhansky M.Ya.
Checked:
department teacher
"Tactical and special training"
Makarevich V.V.
Dnepropetrovsk,
Plan
1. Bad weather
2. Limited visibility
5. Influence of the situation on the road.
Literature
1. Bad weather
If you need to go urgently, and it’s raining heavily, it’s night or the sun is blindingly bright, then most likely this will not stop you. But if you have already decided on a trip in such conditions, only awareness of the difficulties of the upcoming trip is not enough. To protect yourself, you need to know exactly how to act in each case associated with limited visibility.
For example, you are returning home by car. The weather worsened: it became cold, it began to rain. You are having an interesting conversation with a friend sitting with you, discussing problems that concern both of you. At the same time, you casually glance at the road, not paying too much attention to it, but concentrating on the conversation. You know the road well, you have traveled along it many times, you are used to the idea that it will lead you where you need to go ... Suddenly you find yourself in a dense fog. creeping along the ground. Moreover, they found the fog when it had already tightly enveloped your car, and the road completely disappeared from sight. Speed about 80 km/h. Another moment, and you are in a ditch on the opposite side of the road. It turns out that the fog hid a sharp turn.
You and your passenger were not seriously injured, but escaped with bruises and scratches. But what about poor car! Causes of the incident: you were moving too fast; the fog was a surprise; while driving, you did not fully focus on driving.
Each of these causes has contributed. However, most likely, the events would not have turned out in such an unpleasant way if it were not for the fog. If not for him, you probably would have returned home calmly. It was because of the fog that you missed the turn, because it was hidden from you. The fog has limited your visibility.
2. Limited visibility
Limited visibility- this is when it is impossible to distinguish between the road, other vehicles, pedestrians, road signs and objects you need to see in order to drive safely.
Visibility is limited by the following factors: weather (rain, snow, fog, hail, bright sun); road conditions (trucks, buses and other large vehicles, poor organization traffic, “blind” intersections, “blind” roadside sections; turns, rises, objects near the road; bushes, trees, buildings, standing vehicles, etc.); your car (stickers on the windshield or rear window, dirt on the windshield or rear window, knick-knacks dangling from the rearview mirror, cracks in the glass, curtains on the windows, side pillar between the rear and front doors, forms the so-called “blind” zone, passengers in the back and front seats).
Limited visibility makes it impossible for you to see objects road conditions at a fairly distant distance. It is difficult for you to understand what is happening around you. To get the much-needed conditions limited visibility information about the situation on the road, you have to significantly increase your attention, which requires a lot of effort.
Other road users are in the same position at this time. And each of them (just like you yourself) can make a mistake at any moment. You have to be ready for this.
The incident described at the beginning of this chapter is a prime example of what can happen when visibility is limited due to weather conditions.
Another example. Let's say you're driving on a road in heavy traffic with a large vehicle in front of you. freight car. You cannot change lanes, the lane to your left is occupied by moving vehicles. To the right is the curb. The truck blocks your view, so you can't see the road signs ahead of time. As a result, you miss the sign you need, the desired turn and are forced to move to the next intersection.
Another example. You are driving all day long on a country road. Insects, dust, dirt - all this on the windshield of your car. Suddenly, a dog runs out into the road, you notice it at the last moment. To save the dog, you make a sharp turn into oncoming traffic. Well, if on oncoming lane nobody here. What if there is an oncoming car? And all because through a dirty window you did not see the dog in time.
Of course, all these three circumstances described in the examples can gather in one place at once, and a very difficult, dangerous situation. Usually this is exactly what happens: in conditions of insufficient visibility, critical situations arise for several reasons.
For example, a car’s windshield is splashed with dirt, the bright sun shines into your eyes (glare is especially strong through dirty glass), and a large vehicle is moving ahead, blocking the visibility of the situation ahead, and all this at the same time.
Accident statistics show that in conditions of limited visibility, the probability of road accidents increases significantly.
During fog, snowfall, in other conditions limiting visibility ahead, speed reduction is simply necessary for all road users. Otherwise, a chain reaction of collisions with big amount participants and as a result of the victims. Two conclusions follow from the foregoing: 1) in conditions of limited visibility, you are deprived of the opportunity to see all the necessary objects of the road situation;
2) because you can't see well or not at all, you don't know what to expect.
What to do in such situations? You have two means at your disposal: the car and, first of all, your eyes.
The car has special equipment designed to improve driving conditions with limited visibility.
If there is water on the windshield, turn on the windshield wipers. Adjust the speed of the brushes depending on the amount of water (or snow) falling on the glass. If water freezes on the windshield, forming a crust of ice on it, or snow is not completely removed with brushes and blocks your visibility, turn on the heater and warm air will melt the ice. And then turn on the wiper again, which will remove melted ice, snow from the glass.
If the heater does not work, stop and check if all windows are closed (if not, close). Then turn on the heater again. Warm air will warm the windows from the inside, ice or snow will melt, and then you can turn on the wiper. Helpful Hints:
do not use the washer when it is very cold - at very low air temperatures, the water will instantly freeze and form a new crust of ice on the windshield;
Before turning on the windshield wiper, make sure that the windshield has accumulated enough water or snow. Otherwise, the brushes will scrape against dry glass and may damage it, leaving scratches.
Glasses are damp and foggy. When there is moisture on the windshield, turn on the heater. And in cold weather turn on the feed warm air, and in damp, cool, foggy - cool. You can open the windows, this will also help dry the glass. If the glasses are heavily fogged, wipe them dry with a cloth, but not with your hand.
The bright sun pleases sunbathers on the beach, and the driver is not always. If the sun is on the side, and you are driving along the alley, then the dark areas are constantly replaced by brightly lit ones. Such a “light fence” is dangerous in that it causes eye fatigue and makes road signs inconspicuous. signs and small obstacles on the road (pits, stones, foreign objects). If you have dark glasses, put them on: they will smooth out the contrast. If not, squint and tilt your head back a little.
It is best to avoid driving into the sun. If that's not possible, lower your car's sun visor, wear tinted glasses, and most importantly, keep your car clean. front glass. Take the time to clean it up. Moving with your back to the sun, increase the distance to the leader, as the bright sun makes it difficult to correctly and quickly perceive stoplights. Traffic lights require special care.
In bright light, it is easy to confuse the signals, so also be aware of the actions of other road users.
When visibility is limited, turn on parking lights or even low beam headlights. It is likely that visibility conditions will not improve for you, but you will be clearly visible to other drivers, and this is also very important.
Instruments are instruments, but you can improve driving conditions yourself if you realistically assess the factors that limit visibility and change your behavior accordingly. For example, the weather is clearly not conducive to driving, slow down, choose the best position on the road, in extreme cases, pull off the road, stop and wait until visibility improves.
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 endanger yourself and others, leave the road by finding comfortable spot, and wait there until visibility improves. When you stop, don't forget to identify yourself by including alarm.
Pay close attention to other road users, their signals and movements.
Keep the right edge of the road, sidewalk, curb, marking line (edge of the carriageway), shoulder at all times. Hold on to this edge, don't lose it. Choose a position on the road to be at the greatest possible distance from other road users moving towards, i.e., provide the largest lateral interval.
Adjust the rearview mirrors. When the traffic is heavy, you need to very quickly assess the situation both in front and behind, and when driving there is no time to adjust the mirrors.
Keep a close eye on other road users. Look for signs that a large vehicle may be moving ahead of you and blocking your visibility. Avoid long driving behind large vehicle. If you still have to follow him, increase the distance to improve visibility conditions: see signs, traffic lights, markings, intersections, oncoming traffic.
Choose a lane so as to provide as much safety as possible on all sides.
And a few more tips when visibility is limited due to your vehicle:
remove all unnecessary stickers, labels, curtains from windows;
do not place things in front of or behind rear window, they limit visibility;
do not drive with a damaged windshield. On such glass there may be cracks, rays diverging from the place of damage. Such cracks either limit visibility or distort the picture of the road situation;
if the wiper blades are bent, repair them or buy new ones. If you intend to drive a vehicle of a brand new and unfamiliar, study dashboard so that it becomes as familiar and familiar as the one that was on your old car. If you familiarize yourself with the instruments while driving, your attention will be diverted from observing the situation on the road.
3. Fog.
In the fog, the distance to all objects seems to be greater than it actually is. Therefore, the thicker the fog, the greater the distance. The car, whose parking lights you dimly see ahead, may not move, but stand. Don't get close to him high speed. In very heavy fog, sound your horn before changing lanes or returning. If the visibility is very poor, but you have to go, bring your eyes closer to windshield. This will slightly improve visibility, but, however, increase fatigue. When driving in fog, turn on the low beam instead of the high beam. Fog lights are useful if they are properly installed and adjusted. The light from them should spread along the road under a layer of fog and well illuminate the right edge of the road.
If there is a line that limits the edge of the roadway, then you can navigate in the fog along it. It is dangerous to take to the right strongly, cars and people can be on the side of the road.
Don't try to get past the fog in the low ground. It is in this short section that all sorts of surprises can be hidden by fog. Remember that fog changes the color of all colors except red (yellow appears reddish, green appears yellowish).
Keep the windows of the driver's and passengers' doors down to better "hear" the road.
4. Rain.
In the rain, do not approach the leader: the dirt thrown off by the wheels of his car will splatter your glass. If you are overtaken and there are puddles on the road, turn on the glass cleaners in advance. An overtaking car can send a portion of water into your glass, and you will completely lose visibility. Reduce speed before puddles. Firstly, splashes with mud can completely deprive you of visibility, and secondly, there can be holes under the water. Water entering into brake pads, can significantly degrade braking performance. Therefore, after driving through a puddle, lightly press the brake several times to dry the lining. If a thunderstorm has begun, then you should not stop near the old sprawling trees. During a thunderstorm, they often break off and can damage the car body.
In heavy rain, turn on not only the side lights, but also the dipped beam. Choose a speed that matches your visibility. Do not brake sharply, do not suddenly change lanes. Remember that others see you poorly. In case of poor visibility, it is better to refrain from overtaking. side glass it is better to raise it almost to the stop, otherwise a portion of cold water from an oncoming or overtaking car may get into the face, behind the collar. Usually a person does not like it, and most importantly, in these moments he loses control of the car.
5. Influence of the situation on the road.
On straight sections, visibility depends only on the longitudinal profile, on curved sections, on the arrangement of shoulders and the right of way of the road. Green spaces, hills, and buildings close to the roadside impair visibility and safety of the road. Poor visibility of the road is often the cause serious accidents. Especially often accidents in these conditions occur when overtaking. They occur due to the fact that in case of poor visibility or visibility, the driver does not receive information about the situation on the road in time and does not have time to take the necessary actions.
Characteristically, the number of accidents depends not only on the presence of areas with limited visibility and visibility on the roads, but also on the frequency of their location on the highway.
Studies show that rare places of limited visibility and visibility are more dangerous than common places, such as, for example, on mountain roads. In these cases, poor conditions are compensated by the constant increased attention of drivers, and the speed of vehicles is much lower than in flat conditions. Limited (closed) visibility is dangerous at the intersections of roads and streets, on railway crossings, traffic collisions occur more often here than at intersections with an unrestricted view.
Table 1.
Typical places of deterioration in visibility and visibility on the streets and roads
| Characteristic places | Brief description of the site | Possible dangerous consequences |
| 1 | 2 | 3 |
| Road in hilly area | Due to frequent ascents and descents, the longitudinal visibility of the road is insufficient | Collision with a car left on the roadway (due to a malfunction), not visible due to a fracture Loss of control due to road defects (destruction, pits, etc.) not visible due to the fracture |
| Closed turn, mountain roads | Closed view, insufficient information about traffic on the site | Collision with oncoming (and passing) transport; loss of control due to damage not visible behind the turn |
| Road in the forest with a small right-of-way | Unexpected day off carriageway because of the trees people and animals | Hitting people, animals; hitting a tree due to loss of control |
| Entrance to the tunnel | Sharp transition to an area with worse illumination | Collisions with oncoming, passing vehicles, collision with fences |
| Street crossings in cities | Closed view, insufficient traffic information | Collisions, collisions with pedestrians |
| Public transport stops | Unexpected exit of pedestrians | Pedestrian collision |
| Railroad crossing | Unexpected train departure due to obstruction | Train collision |
Characteristic places limited terms visibility and visibility are presented in table. 1.
Literature
1. Timovsky O.A., Z.D. Derekh, Zavoritsky Yu.Є. Fundamentals of safe care by road transport facilities. - K .: "Vishcha school", 2004. 120 p.
2. Zhulev V.I. Driver and road safety. - M.: DOSAAF, 1984. - 151 p.
3. Bezsmertny V.O., Derekh Z.D., Ishchenko V.V. Fundamentals of car care and traffic safety. - K .: Vishcha school, 1996. - 201 p.
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
In accordance with traffic rules the driver must 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 movement transport.
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 the 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;
Movement uphill should be made on more increased speed engine, approximately + 20% to 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 the road surface is 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. good helper will be of 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 slope, switch to downshift, but do not twist the engine - you will overheat 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.
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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 vehicle in all road conditions, and especially in difficult ones, is a good technical condition 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.
You should avoid sudden changes, accelerations, and braking, trying to drive the car as straight as possible, and if aquaplaning occurs due to a sharp deterioration in the contact of automobile tires with the road surface, you must smoothly and gradually release the gas pedal, thus performing soft braking, and resuming contact of the tires with the road surface. coated.
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, and 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.
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 of the traffic flow and are associated with weather and climatic 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 with the greatest 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 regulation 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: Windshields and headlights are splashed with mud or snow, brake pads water gets in, condensate forms in the pneumatic drive of the brakes, 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. On pavement a layer of snow is formed, 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 ensuring road safety. 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.
