The main types of accidents that require ASR. Determining the location of a vehicle collision Based on the nature of mutual approach

When studying the mechanism of a collision in the process of approaching a vehicle, the expert establishes either a violation of stability or loss of control before the collision and the reasons for such a violation, determines the speed of the vehicle before the incident and at the moment of the collision, establishes their location at certain times, the lane, the direction of movement, the angle of contact at collision.

By examining the process of vehicle interaction, the expert establishes their relative position at the moment of impact, determines the direction of the impact and its impact on the movement under study.

When studying the process of throwing a vehicle after a collision, the expert determines the location of the collision based on the remaining traces and the location of the vehicle after the incident, determines their speed of movement after the impact, and the direction of the throwing.

Establishing by an expert the mechanism of the collision and a technical assessment of the actions of the participants in the incident allow the investigative authorities and the court to resolve the issue of the cause of the incident and the circumstances that contributed to its occurrence.

The expert research methodology for establishing the collision mechanism depends on the type of collision. According to the main classification criteria that determine the collision mechanism, all vehicle collisions can be divided into the following groups:

According to the angle between the directions of movement of the vehicle - longitudinal (when driving parallel or close to parallel) and cross collisions. Longitudinal collisions are divided into oncoming and passing;

According to the nature of the interaction at the contact site during an impact - blocking (with complete damping of the relative speed at the moment of impact), sliding and tangential collisions.

These signs characterize the collision mechanism of both vehicles. In addition, the collision of each of the two colliding vehicles can be characterized by features unique to this vehicle:

By the nature of the movement immediately before the impact - a collision without reserve, with reserve to the right or left;

According to the place where the impact impulse is applied - a side collision is right - or left, front, rear, corner;

According to the direction of the impact impulse - the collision is central (when the direction of impact passes through the center of mass of the vehicle), right - or left eccentric.

This collision classification system makes it easy to formalize the characteristics of a collision.

§ 2. Mechanism of vehicle collision

General concept of the collision mechanism

The mechanism of a vehicle collision is a complex of circumstances related to objective laws that determine the process of vehicles approaching before a collision, and the interaction during the impact and subsequent movement until it stops; analysis of data on the circumstances of the incident allows the expert to establish the relationship between individual events, fill in the missing links and determine the technical cause incidents. A formal solution by an expert to questions based on individual scattered data, without a technical assessment of their compliance with each other and established objective data, without revealing and explaining the contradictions between them, can lead to incorrect conclusions.

When studying the mechanism of an incident, signs that directly allow one to establish one or another circumstance may be absent. In many cases, it can be established based on data about other circumstances of the incident, by conducting an expert study based on patterns that connect all the circumstances of the incident mechanism into a single set.

Features of impact in a collision

The theory of impact is based on ideal conditions, which greatly simplify the understanding of the interaction of bodies during impact. Thus, it is assumed that the contact of colliding bodies occurs at one point through which the interaction force passes, that the surfaces of the colliding bodies are absolutely smooth, there is no friction or engagement between them. Therefore, the impact force is perpendicular to the plane tangent to the surface of the colliding bodies at the point of their contact. The duration of the impact is assumed to be zero, and since the force impulse has a finite value, the impact force is considered to occur instantly, reaching an infinitely large value. The relative displacement of the colliding bodies during the impact is also considered to be zero, and therefore, the mutual repulsion of the colliding bodies occurs only under the influence of elastic deformation forces.

The interaction of a vehicle in a collision is much more complex than described above. During a vehicle collision, contact between them occurs over large areas, and various parts enter into it, causing interaction forces to appear in different places. The direction and magnitude of these forces depends on the design of the contacting parts (their shape, strength, rigidity, nature of deformation), therefore the interaction forces are different at different points of contact. Since the deformation of a vehicle during a collision can be very significant in depth, the interaction forces are variable in magnitude and direction.

The collision time is very short. There, no less than the relative displacement of the vehicle during this time can significantly affect their movement after the collision.

The direction of impact in a collision and the main direction of deformation of the contacting parts do not always coincide with the direction of the relative speed of the vehicle. They can coincide only in cases where the contacting areas do not slip during the impact. If slipping occurs over the entire surface, then transverse components of interaction forces arise, causing deformations in the direction of the least rigidity, and not in the direction of the longitudinal components, where the rigidity and strength of the deformed parts can be much higher (for example, when hitting at an angle on the side of the door the surface of the cabin is deformed not in the direction of the impact, but in the transverse direction if the impact was sliding).

It is also impossible to assume that the line of impact (the vector of the resultant impulses of the impact forces) during a collision passes through the point of initial contact. If the area of ​​the deformed area is large, the main blow can be delivered at a considerable distance from this point when interacting with stronger and more rigid parts than at the point of initial contact.

The vehicle collision mechanism can be divided into three stages: vehicle approach before the collision, interaction upon impact, and kickback (movement after the collision).

First stage of the collision mechanism– the process of rapprochement – ​​begins from the moment a danger to traffic arises, when in order to prevent an incident (or reduce the severity of the consequences) the drivers must immediately take the necessary measures, ends at the moment of initial contact of the vehicle. At this stage, the circumstances of the incident are determined to the greatest extent by the actions of its participants. At subsequent stages, events usually develop under the influence of irresistible forces arising in accordance with the laws of mechanics. Therefore, in order to resolve issues related to the assessment of the actions of the participants in the incident in terms of compliance with their traffic safety requirements, it is of particular importance to establish the circumstances of the incident at its first stage (the speed and direction of movement of the vehicle before the incident, their location along the width of the roadway).

Some circumstances of the incident at the first stage cannot be established directly on the spot or through questioning witnesses. Sometimes they can be established through expert examination of the collision mechanism at subsequent stages.

Second stage of the collision mechanism– interaction between vehicles – begins from the moment of initial contact and ends at the moment when the influence of one vehicle on another stops and they begin to move freely.

The interaction of a vehicle in a collision depends on the type of collision, determined by the nature of the impact, which can be blocking or sliding. During a blocking impact, the vehicles seem to stick together in separate sections, and there is no slipping between them. During a sliding impact, the contacting areas are displaced relative to each other, as the speed of the vehicles is equalized.

The process of a vehicle collision during a blocking impact can be divided into two phases.

In the first phase, deformation of the contacting parts occurs as a result of their interaction. It ends when the relative speed of the vehicle in the contact area drops to zero and lasts a fraction of a second. Enormous impact forces, reaching tens of tons, create large decelerations (accelerations). With eccentric impacts, angular accelerations also occur. This leads to different changes in the speed and direction of movement of the vehicles and their turn. But since the impact time is negligible, the vehicles do not have time to significantly change their position during this phase, therefore the general direction of the deformations usually almost coincides with the direction of the relative velocity.

In the second phase of the blocking impact, after the completion of mutual penetration of the contacting sections, the vehicles move relative to each other under the influence of elastic deformation forces, as well as mutual repulsion forces arising during an eccentric impact.

The magnitude of the impulse of elastic deformation forces compared to the impulse of impact forces is large. Therefore, with a slight eccentricity of the impact and deep penetration of the contacting parts, the adhesion forces between them may prevent the separation of the vehicle and the second phase of the impact may end before their separation.

A sliding collision occurs in cases where the velocities in the contact areas are not equalized and before the vehicles begin to move away from each other, the interaction occurs sequentially between their different parts located along the line of relative displacement of the contacting areas. In the event of a glancing impact, the vehicle manages to change its relative position during the collision, which somewhat changes the direction of the deformations.

During contact, transverse velocities of the vehicles arise, which leads to a deviation in the direction of their deformations.

A sliding impact with a small depth of mutual penetration and a high speed of relative displacement is called a tangential impact. With such an impact, the vehicle speeds after the collision change slightly, but the direction of their movement will change significantly.

The classification of types of vehicle collisions, which meets the needs of automotive technical expertise, should contribute to the selection of methods and the most complete development of a methodology for expert research of the circumstances that determine the mechanism of the collision.

The classification of types of collisions is shown in Figure 2.1.

Figure 2.1 - Classification of types of vehicle collisions

Common features include the following:

1 The movement of one vehicle transversely in relation to the lane of another as they approach each other (classification according to the direction of movement of the vehicle). The sign is determined by: the value of the collision angle b, which can be established by the tracks of the wheels of both vehicles before the collision, by the location of the vehicle and traces of their movement after the incident, by the direction of throwing objects separated from them (glass fragments, etc.), by the deformations obtained during the collision .

Based on this criterion, collisions are divided into 2 groups:

• a) longitudinal - a collision without a relative displacement of the vehicle in the transverse direction, i.e. when moving in parallel courses (angle b is 0 or 180°);
• b) cross collision - a collision when the vehicle is moving on non-parallel courses, i.e. when one of them shifted transversely towards the lane of the other (angle b is not equal to 0 or 180°);
• 2 Movement of vehicles in the longitudinal direction in relation to each other (classification according to the nature of the mutual approach of the vehicles). The sign is also determined by the magnitude of the collision angle b.

Based on this criterion, collisions are divided into three groups:

• a) oncoming - a collision in which the projection of the speed vector of one vehicle onto the speed direction of the other is opposite to this direction; The vehicles approached each other with a deviation towards each other (angle >90°,
• b) passing - a collision in which the projection of the speed vector of one vehicle onto the speed direction of the other coincides with this direction; The vehicles approached each other, moving with a deviation in one direction (angle b
• c) transverse - a collision in which the projection of the speed vector of one vehicle onto the speed direction of the other is zero (angle b is 90°, 270°).

If angle b differs so little from zero or from 90° that the research methods used do not allow us to establish this deviation, and if the possible deviation does not have a significant effect on the collision mechanism, then the latter can be defined as longitudinal or transverse, respectively.

3 Relative location of the directions of the longitudinal axes of the vehicle at the moment of the collision. The sign is determined by the value of the angle of mutual arrangement of their longitudinal axes b0, which is established on the basis of traceological studies of traces and damage in places of direct contact of the vehicle during a collision. In some cases, the angle b0 can be set according to the wheel tracks in front of the collision site.

• a) direct - a collision with a parallel arrangement of the longitudinal or transverse axis of one vehicle and the longitudinal axis of the other (angle b0 is 0.90?);
• b) oblique - a collision in which the longitudinal axes of the vehicle were located at an acute angle relative to each other (angle b0 is not equal to 0.90?).
• 4 The nature of the interaction of contacting parts of the vehicle during a collision. The sign is determined by deformations and marks on the contact areas.

Based on this criterion, collisions are divided into groups:

• a) blocking - a collision in which, during contact, the relative speed of the vehicle in the contact area by the time the deformations are completed is reduced to zero (the forward speeds of the vehicle in this area are equalized). In such a collision, in addition to dynamic ones, static traces (prints) remain on the contact areas;
• b) sliding - a collision in which, during the contact process, slipping occurs between the contacting areas due to the fact that until the moment the vehicle leaves contact with each other, the speeds are not equalized. In this case, only dynamic traces remain on the contacting areas.
• c) tangential - a collision in which, due to the small amount of overlap of the contacting parts of the vehicle, they receive only minor damage and continue to move in the same directions (with a slight deviation and a decrease in speed). In such a collision, horizontal traces (scratches, rubbing marks) remain in the contact areas. An accident is not a consequence of interaction forces upon impact, but of subsequent collision with other obstacles.
• 5 The direction of the vector of the resultant of the impact impulse vectors (direction of the collision line) in relation to the location of the center of gravity of the given vehicle, which determines the nature of its movement after the collision (with or without a turn). Based on this criterion, collisions are divided into 2 groups:
  • a) central - when the direction of the collision line passes through the center of gravity of the vehicle;
  • b) eccentric - when the line of collision passes at a certain distance from the center of gravity, to the right (right eccentric) or to the left (left eccentric) of it.
• 6 Location along the perimeter of the vehicle of the area that was in contact during the impact (classification according to the location of the impact). The sign (along with the relative position angle b0) determines the relative position of the vehicle at the moment of the collision.

Based on this criterion, collisions are divided into the following groups:

• a) front (frontal) - a collision in which traces of direct contact upon impact with another vehicle are located on the front parts;
• b) front corner right and c) front corner left - a collision in which traces of contact are located on the front and adjacent side parts of the vehicle;
• d) side right and e) side left - a collision in which the impact was applied to the side of the vehicle;
• f) rear corner right and g) rear corner left - a collision in which traces of direct contact are located on the rear and adjacent side parts of the vehicle;
• h) rear - a collision in which the contact marks caused by the impact are located on the rear parts of the vehicle.

This system of classification of types of collisions allows us to cover all possible types of two or more vehicle collisions and formalize the characteristics of any collision.

Depending on the need, a collision may not be characterized by all classification criteria, but only by some of them. Other classification groups may be included in the proposed classification system, depending on the purpose of the classification.

The main types of road accidents that require ASR are collisions, which are divided into:

windshield- vehicle collision in oncoming traffic;

lateral- collision of a vehicle with the side of another vehicle;

tangent- collision of a vehicle with its sides during oncoming traffic or movement in one direction;

capsizing- an incident in which a moving vehicle overturned;

hitting a standing vehicle- an incident in which a moving vehicle collided with a stationary vehicle, as well as a trailer or semi-trailer;

hitting an obstacle- an incident in which the vehicle ran over or hit a stationary object (bridge support, pole, tree, fence, etc.).

Special types of accidents that require ASR

Special types of accidents- Road accidents complicated by dangerous factors requiring special training of rescuers or the involvement of additional forces and resources.
Accident with vehicle falling into water- Road accidents in which vehicles for some reason fall into rivers, lakes, the sea, fall through ice, etc.
Accident with vehicle falling from steep slopes- Accidents in which vehicles, for some reason, fall off steep slopes and, when falling, usually roll over several times, hitting rock ledges, and fly 100–150 m or more. Sometimes vehicles explode. The vehicles themselves turn into a pile of twisted metal.
Accident on a railway section- road accidents in which: a vehicle collides with a moving or stationary train at a railway crossing or on a section of the railway not intended for crossing; A vehicle collides with another vehicle at a railway crossing; a rolling stock collides with a vehicle at a railway crossing or on a section of the railway not intended for crossing.
Accident involving a tram (trolleybus)- Accidents in which a tram (trolleybus) collided (ran over) into another vehicle, or as a result of power wires breaking and falling on the vehicle, or a tram derailing and overturning, the vehicle or people were injured.
Road accident with fire– Road accident, accompanied by fire of emergency vehicles and the cargo they transport.
Vehicle falling under a rubble- An accident in which a vehicle with people as a result of natural or man-made phenomena was caught in an avalanche, mudflow, landslide, rockfall, etc.
Accident in a tunnel (overpass)- Road accidents complicated by the specifics of a limited space, which makes it difficult to access the accident site, carry out emergency response and evacuate victims.
Accident with a vehicle carrying dangerous goods- An accident with a vehicle carrying cargo that falls under the category of dangerous, as a result of which there was a leak (ejection, fire, etc.) or there is a danger of such a situation, including:
- an accident with a vehicle transporting flammable liquids (FL) or flammable liquids, which resulted in a spill or leak;
- an accident with a vehicle transporting hazardous chemical substances (HAS), which resulted in a spill or leak;
- an accident with a vehicle transporting radiation hazardous substances (RH), as a result of which there was a spill or leakage, resulting in environmental pollution;
- an accident with a vehicle transporting biologically hazardous substances (BH), as a result of which there was a spill or leakage, resulting in contamination of the environment;
- An accident with a vehicle transporting explosives and explosive objects, in which there was a threat of detonation of explosives and high explosives due to their movement, mechanical impact on them or heating (combustion).

To understand the scale of car damage after an accident, you need to clearly understand what happens directly at the moment of impact with the car body, which areas are subject to deformation. And you will be unpleasantly surprised to learn that during a frontal impact, the rear part of the body is skewed.

Accordingly, after unscrupulous body repair of the front end, even if the car was on the slipway, you will observe the trunk lid sticking, the sealing rubber rubbing, and much more. If you are interested in this topic, I suggest that you familiarize yourself with the educational material on collision theory, which was prepared by the specialists of our educational center.

General information

Theory collisions – This knowledge And understanding strength, emerging And existing at collision.

The body is designed to withstand the impacts of normal driving and to ensure the safety of passengers in the event of a vehicle collision. When designing the body, special care is taken to ensure that it deforms and absorbs the maximum amount of energy during a serious collision, while at the same time causing minimal impact on occupants. For this purpose, the front and rear parts of the body must be easily deformed to a certain extent, creating a structure that absorbs impact energy, and at the same time these parts of the body must be rigid in order to maintain a separation area for passengers.

Determination of violation of the position of body structural elements:

• Knowledge of collision theory: Understanding how a vehicle's structure reacts to the forces generated during a collision.
• Body inspection: search for signs indicating structural damage and its nature.
• Taking measurements: basic measurements used to identify violations of the position of structural elements.
• Conclusion: application of knowledge of collision theory in conjunction with the results of external inspection to assess the actual violation of the position of a structural element or elements.

Types of collisions

When two or more objects collide with each other, the following collision options are possible:

According to the initial relative position of objects

• Both objects are moving
• One is moving and the other is stationary
• Additional collisions

In the direction of impact

• Frontal collision
• Rear collision
• Side collision
• Rollover

Let's look at each of them

Both objects are moving:

One is moving and the other is stationary:

Additional encounters:

Front collision (frontal):

Rear collision:

Side collision:

Tipping:

Influence of inertial forces during a collision

Under the influence of inertial forces, a moving car tends to continue moving in a forward direction and when it hits another object or car it acts as a force.

A car standing still tends to maintain a stationary state and acts as a force opposing another car that hits it.

When colliding with another object, an "External Force" is created

As a result of inertia, “Internal forces” arise

Types of damage

Impact force and surface

Damage will vary for given vehicles of the same weight and speed depending on the object of the collision, such as a pole or wall. This can be expressed by the equation
f = F / A,
where f is the magnitude of the impact force per unit surface
F - force
A – impact surface
If the impact falls on a large surface, the damage will be minimal.
Conversely, the smaller the impact surface, the more severe the damage will be. In the example on the right, the bumper, hood, radiator, etc. are seriously deformed. The engine is moved rearward and the consequences of the collision reach the rear suspension.

Two types of damage

Primary damage

The collision between the vehicle and the obstacle is called the primary collision, and the damage it creates is called primary damage.
Direct damage
Damage caused by an obstacle (external force) is called direct damage.
Ripple Effect Damage
The damage created by the transfer of impact energy is called ripple effect damage.
Damage caused
Damage caused in other parts experiencing a tensile or pushing force due to direct damage or damage from the wave effect is called induced damage.

Secondary damage

When a car hits an obstacle, a large deceleration force is generated, which stops the car within a few tens or hundreds of milliseconds. At this point, passengers and objects inside the vehicle will attempt to continue moving at the vehicle's speed prior to the collision. A collision that is caused by inertia and that takes place inside the vehicle is called a secondary collision, and the resulting damage is called secondary (or inertial) damage.

Categories of violation of the position of parts of the structure

• Forward offset
• Indirect (indirect) displacement

Let's consider each of them separately

Forward offset

Indirect (indirect) displacement

Shock Absorption

The car consists of three sections: front, middle and rear. Each section, due to the nature of its design, reacts independently of the others in a collision. The car does not react to impact as one inseparable device. At each section (front, middle and rear), the influence of internal and (or) external forces manifests itself separately from other sections.

Places where the car is divided into sections

Crash-absorbing design

The main purpose of this design is to effectively absorb impact energy by the entire body frame in addition to the destructible front and rear parts of the body. In the event of a collision, this design ensures minimal deformation of the passenger compartment.

Front part of the body

Since the risk of collision is relatively high for the front end, in addition to the front side members, upper wing apron reinforcements and upper body side panels with stress concentration zones are provided to absorb impact energy.

Rear body

Due to the complex combination of rear quarter panels, rear floor box and spot welded elements, the impact absorption surfaces are relatively difficult to see in the rear, although the concept of impact absorption remains similar. Depending on the location of the fuel tank, the impact absorption surface of the rear floor side members is modified to absorb impact energy from collisions without damaging the fuel tank.

The ripple effect

Impact energy is characterized by the fact that it easily passes through strong areas of the body and finally reaches weaker areas, damaging them. This is the principle of the ripple effect.

Front part of the body

In a rear wheel drive vehicle (FR), if impact energy F is applied to the leading edge A of the front side member, it is absorbed through damage to zones A and B and also causes damage to zone C. The energy then passes through zone D and, after changing direction, reaches zone E. Damage, created in zone D is shown by the rearward displacement of the spar. The impact energy then causes ripple effect damage to the instrument panel and floor box before spreading over a larger area.

In a front-wheel drive vehicle (FF), the energy from a frontal impact will cause intense destruction of the front section (A) of the side member. The impact energy, causing the rear section B of the side member to bulge, eventually causes damage to the instrument panel (C) from the ripple effect. However, the ripple effect on the rear (C), reinforcement (lower rear spar) and steering gear bracket (lower instrument panel) remains negligible. This is because the central part of the side member will absorb most of the impact energy (B). Another characteristic of a front wheel drive (FF) vehicle is also damage to the engine mounts and surrounding areas.

If the impact energy is directed toward area A of the wing apron, the weaker areas B and C along the impact path will also be damaged, allowing some of the energy to be absorbed as it travels rearward. After zone D, the wave will impact the top of the post and the roof longitudinal beam, but the impact on the bottom of the post will be negligible. As a result, the A-pillar will tilt backwards, with the bottom of the A-pillar acting as a pivot point (where it connects to the panel). The typical result of this movement is a shift in the door landing area (the door becomes misaligned).

Rear body

Impact energy on the rear quarter panel causes damage at the contact area and then at the rear quarter panel. Also, the rear quarter panel will slide forward, eliminating any gap between the panel and the tailgate. If higher energy is applied, the rear door may be pushed forward, deforming the B-pillar, and damage may extend to the front door and A-pillar. Damage to the door will be concentrated in the folded areas at the front and rear of the exterior panel and in the door lock area of ​​the interior panel. If the rack is damaged, a typical symptom is a door that doesn't close properly.

Another possible direction of the wave effect is the path from the rear side pillar to the longitudinal beam of the roof.

In this case, the rear of the roof rail will be pushed up, creating a larger gap at the rear of the door. The junction between the roof panel and the rear side body is then deformed, causing the roof panel above the B-pillar to deform.

The location of vehicle damage from contact with each other makes it possible to determine their relative position at the time of the collision and to clarify the location of the collision if the location and direction of movement of one of them at the time of the collision are established.

Sometimes the angle is determined from photographs of damaged vehicles. This method gives good results only when pictures of different sides of the car are taken at right angles from the same distance. Due to the fact that measuring vehicle deformation and taking photographs to determine the collision angle requires certain skills and knowledge, it is advisable to carry them out with the participation of experts.

The direction of deformation, which determines the direction of the impact, makes it possible to determine the possible displacement of the vehicle from the collision site, and by its location after the incident, to clarify the location of the collision.

The nature of the deformations makes it possible to establish the collision angle of the vehicle and, by calculation, determine the value of the interval between the moving parallel courses of the vehicle before turning one of them into the lane of the other (based on the maximum adhesion radius of the turn). This allows you to clarify the location of the collision based on the width of the lane.

Rice. 4. Types of location of vehicles at the time of an accident.

The location of the damage on the lower parts of the vehicle, which left tracks on the road during a collision, makes it possible to clarify the position of the vehicle along the width of its lane when these tracks were formed at the collision site.

Examination of damage to painted and metal parts makes it possible to determine the direction of movement of the colliding vehicles. Marks on the surface of a damaged car that are wider than deep and longer than wide are called scratches. Scratches run parallel to the damaged surface. They have a small depth and width at the beginning, widening and deepening towards the end. If the primer is damaged along with the paintwork, it peels off in the form of wide, drop-shaped scratches, 2-4 mm long.

Damage that is deeper than wide is called nicks or dents. The depth of the scratch usually increases from its beginning to its end, which makes it possible to determine the direction of movement of the scratched object. Sharp burrs often remain on the surface of the scratch, which are bent in the same direction in which the scratched object moved. The car that was moving slower had scratch marks directed from the rear to the front, while the car that was overtaking had scratch marks in the opposite direction.

In the event of an oncoming collision, the speeds of the vehicles cancel each other out. If their mass and speed were the same, then they stop near the collision site. If the masses and speeds were different, then the car moving at a lower speed or lighter is thrown back. If the truck driver does not take his foot off the gas pedal at the time of the accident and, confused, continues to press it, then the truck can drag an oncoming passenger car to a fairly large distance from the collision site.