a) The anchor point of the scene of the incident along the length of the carriageway to a fixed stationary object that cannot be moved is determined, for example, a pole of a power transmission tower, a corner of a structure, a drain pipe, the edge of a bridge, etc.);
c) Technique for making measurements: all measurements must be made exclusively in a rectangular coordinate system / method of fixing the position of a point on a plane /. Regarding the inspection of the accident sites, this is a mandatory point binding:
Along the length of the carriageway: by fixing the distance from a stationary object to it (the fixing method is indicated above);
By the width of the carriageway: by fixing the distance from the edge of the carriageway to it.
For measurements along the length of the road and binding the accident site, it is enough to determine the distance from the stationary object of only one point, which will be the origin of coordinates located at the accident site (vehicle wheel, braking track, blood stain, etc.) and then take measurements , starting from it, moving from one point to the next along the "chain", without returning back.
After taking measurements, drawing up a diagram in a draft version, it is necessary to mentally draw up a diagram again according to the available dimensions. In this case, it may turn out that one or two sizes are missing and they need to be additionally determined.
Diagonal measurements are not permitted! In width, it is necessary to tie only to one side of the carriageway, the most convenient and closest to the scene of the incident.
Do not measure the width from both ends of the carriageway! Ultimately, this will inevitably lead to an error and the need to select one of the measurements made as the correct one, which may raise doubts about the reliability of all the initial data!
d) The binding of the vehicle to the scene of the accident is carried out by base points, which are the centers of the front and rear wheels, while measuring the distance from the edge of the carriageway and the distance of one base point along the length from a stationary object or a point chosen as the origin of coordinates.
e) Visible traces of braking / visible dark traces of rolling of wheels in the form of a tread pattern, left on dry asphalt or concrete, by wheels braking on the verge of stopping rotation
(stopped) wheels / must be carefully measured, because even an insignificant inaccuracy can lead to an erroneous conclusion of an expert when deciding on the speed of traffic. Do not use the expression "braking distance" / the distance covered by the car from the moment the driver depressing the brake pedal, the braking system is applied and until the vehicle comes to a complete stop /! Visible traces of braking and skidding make up only a part of it.
If the vehicle is at the scene of the accident and its position has not changed, then the traces of braking are measured from the beginning and along the existing trajectory to the wheels with which they were left. If the vehicle is not in place or its position is changed, then the tracks are also measured from their beginning along the existing trajectory to the end.
All start and end points of measurements must be referenced along the length and width of the carriageway in the coordinate system. It is also necessary to indicate which wheels have left traces.
If there are traces of braking of different lengths from the left, right (front, rear) wheels, the length of each trace is indicated separately. If, after the end of the traces of braking, the car was coasting, the length of this distance is indicated. If the brake track is left on a road section with a different surface (when leaving the road during braking), on oily and contaminated areas, then each section of the track is measured separately for each wheel before leaving on another surface and along it until the end of the track or leaving the next section ... In cases where the brake wake is interrupted, the length of each such segment and the size of the intervals between them are indicated.
When describing the traces of a car (motorcycle, bicycle), the protocol of the inspection of the scene of the accident should reflect:
The location of the tracks on the straight-line section, at the turn and the surface on which they were found.
The type and condition of the soil or road surface (asphalt, dirt road, clay, black earth, sandy soil; wet, dry, etc.).
Trace type (superficial, volumetric).
Number of tracks.
The ratio between the tracks of the front and rear wheels (whether the tracks of the front wheels are completely covered, or are some of these tracks preserved in the form of a strip (indicate its width).
Track size.
The width of the display of the tread tread.
The maximum depth of volumetric tracks in relation to the road surface.
The structure of the tread pattern (consisting of checkers, winding, broken lines, etc.).
The shape, size, location of prints, features of the wheel or tire surface (patches, cracks, potholes, etc.).
The length of the track of one turn of the wheel (determined by one of the repeating features).
The length of the braking track.
Features of the brake wake: straight, curved, side skid, etc. For the case of a curved track, a transverse reference is made with an interval in measurements of 1-2 m (depending on the length).
Turning radius.
Signs characterizing the direction of movement.
Parts (details), as well as substances separated from a particular vehicle, their location relative to the vehicle wheel tracks or other landmarks.
Techniques and means used by a specialist to remove traces and other objects.
When determining the direction of travel of the vehicle, consider the following:
In the tire tracks off-road the vertices of the corners of the pattern, as a rule, are directed in the direction opposite to the direction of movement of the vehicle.
The direction of the painted wheel tracks formed as a result of exposure to water and dirt when the car drives over puddles, as well as traces of their drying, coincides with the direction of the car.
The elongated ends of droplets of liquid, oil flowing from the car, during its movement, are directed towards the direction of movement.
The ends of sticks, twigs, and straws broken when the car is being moved are turned towards the direction of travel.
The angle of convergence of the tracks on bends is less than the angle of their divergence.
The bottom of the track sometimes consists of ledges, the gentle sides of which are directed towards the direction of travel.
Rollers are formed near the tracks in the dust, making up with a trace an acute angle, the top of which is directed in the direction of movement.
Pieces of soil are moved by the wheels in the direction opposite to the direction of travel.
The grass is smoothed by the skid wheels in the opposite direction to the direction of travel.
A gap is formed near stones pressed into the ground by the car on the side opposite to the direction of movement of the car.
f) It is during the inspection of the accident site that it is necessary to establish and mark the place of collision with a pedestrian or collision Vehicle and tie it to braking tracks and vehicles.
The place of collision with a pedestrian is established:
At the beginning of the traces of dragging the victim's body - exclusively for cases of collision with a lying person, if there is a reason for the possibility of moving the body during the collision;
On a wet spot of spilled liquid that was in a broken container near a pedestrian;
On the inconspicuous trail of side slip left by the victim's shoes when a car hits him;
On loose dirt from deformed body parts of the vehicle;
On the trajectory of a pedestrian, established by the visible traces of a pedestrian until the moment of collision or according to eyewitnesses of an accident, taking into account the traces of the movement of a vehicle;
According to the driver himself, if there is no other objective data.
When a vehicle hits a pedestrian in an upright position, the latter moves from the collision point to a distance of several or even tens of meters, depending on the speed of movement, for example, at a VAZ-2101 vehicle speed at the moment of a collision of 30 km / h, the pedestrian is thrown away in the direction of travel at a distance of 5 to 7 m, and at a vehicle speed of 60 km / h, the rejection range reaches from 15 to 18 m; this does not take into account the possibility of moving the victim on the hood of the vehicle. Therefore, the place of collision cannot be at the same point with the place where the pedestrian was after the impact or where there are traces left from the victim's body.
Often in decisions on the appointment of an examination, the phrase is found: "The vehicle stopped at the place (at the time) of the collision." This is incorrect, since in order to hit a pedestrian, it is necessary that the transport has at least some speed, and
therefore, when hitting a pedestrian at the end of braking, the collision point should be located within the dimensions of the stopped car at least a few centimeters.
The collision site is established according to the following criteria:
A sharp deviation of the wheel track from the original direction, which occurs when an eccentric impact on transport or when hitting the front wheel;
Lateral displacement of the track resulting from a center, oncoming collision and unchanged position of the front wheels.
With a slight transverse displacement of the track or its slight deviation, these signs can be detected by examining the track in the longitudinal direction from a low height;
Traces of lateral displacement of an unlocked wheel arising at the time of a collision as a result of lateral displacement of the vehicle or a sharp turn of the front wheels. As a rule, such traces are hardly noticeable;
Termination or rupture of the skid track, which occurs at the moment of collision as a result of a sharp increase in load and violation of wheel blocking or its separation from the road surface;
Skid trace of one wheel, which was struck, jamming it and sometimes only for a short period of time. It is necessary to take into account in which direction this trail was formed, based on the location of the vehicle after the accident;
Traces of friction of vehicle parts against the coating during the destruction of its chassis (wheel separation, suspension destruction) or the fall of two-wheeled vehicles (motorcycles, mopeds, etc.). They usually start at the collision site;
Traces of movement of both vehicles. The collision point is determined by the intersection of these tracks, taking into account the relative position of the vehicle at the time of the collision and the location of the parts on them that left traces on the road;
The location of the collision is determined quite accurately by the location of the earth that fell from the lower parts of the vehicle at the moment of impact.
In a collision, earth particles are thrown at high speed and fall onto the road almost at the point where the impact occurred.
The largest amount of soil is separated from the deformable parts of the vehicle: the surfaces of the fenders, mud flaps, the underbody. Establishing the vehicle from which the earth was crumbled is in many cases not difficult, since the contamination of the lower parts of various vehicles differs in quantity and appearance. In doubtful cases, the need for comparative chemical studies may arise;
According to eyewitnesses of the incident or vehicle drivers, when there is none of the above signs.
g) Information about the separated particles in an accident:
When inspecting the scree zones, the boundaries of scattering of various particles should be recorded separately, for example, scree of dried mud, scree of destroyed side glazing of the passenger compartment or cabin, scree of destroyed lighting devices, such as fragments of headlight diffusers, sidelights and side repeaters, scree of exfoliated paintwork, and it is necessary to fix precisely the boundaries of the scattering zones with full reference to the accident site, and not only their central parts. When describing the separated objects, it is necessary to indicate their shape, size, exact location, measuring the distances from them to at least two permanent landmarks, the position of these parts relative to road elements and vehicles on which they are absent, indicate from which points of the vehicle measurements were made (from angles, wheel axles, etc.).
When inspecting the accident sites from which the driver fled, you should carefully collect all the fragments of lighting devices and decorative body linings. In the future, when appointing a forensic examination of the "whole in parts" for combining the fragment left on the car, the part that remained at the scene may not be enough. It is also necessary to collect the largest possible amount of particles of the exfoliated paint-and-lacquer coating for carrying out chemical-physical studies. Fragments of the glazing of the body, the so-called "Stalinite", are of no particular interest to experts.
1. Types of vehicle tracks and their forensic value.
2. Work of the investigator with traces of vehicles.
In the practice of investigating crimes, traces of cars, motorcycles, tractors, horse-drawn carts, sledges are often used. Under vehicle tracks means traces of contact impact of running and non-moving parts of vehicles, traces on objects separated from the vehicle, as well as various materially fixed changes on the road associated with traffic.
At the scene of the accident, vehicles, depending on the situation, can leave traces representing all types of forensic classification.
Display traces(traces of the running gear) are formed in the form of rolling marks or traces of sliding wheels that occur in a braked state (skidding), imprints (volumetric and surface) of the tread pattern, track tracks on the road surface, on the clothes and body of the victim, as well as in the form of dents , chips, scratches, potholes - on obstacles, trees, buildings. Traces in the form of potholes, grooves or scratches remain on the road surface from body parts, running gear or transmission of a vehicle that collapsed as a result of an impact in an accident. The same marks are left by parts (handlebars, footrests, pedals) of the overturned motorcycle. Investigative practice knows cases of displaying protruding parts of a car on a trail-perceiving object, an imprint of its state sign in the ground or in a snowdrift.
Footprints-objects remain at the scene of a traffic accident in the form of car parts - wheels, headlight rims, fragments windshield and glasses of headlights, chips from the body, items of clothing of the victim, part of the cargo transported in the body of the transport.
Substance traces on the spot, for example, a traffic accident is represented by puddles and splashes of fuel and lubricants, coolant and brake fluid, as well as objects of biological origin (blood, hair, brain matter). Traces-substances also include paintwork particles that are mutually transferred from one vehicle to another when they collide. These traces include, in addition, the accumulation of particles of dirt, dust, earth, crumbled from the lower parts of the car in a collision with an obstacle.
Depending on the nature of the road surface vehicle tracks are divided into volumetric (depressed) and superficial. Volumetric traces represent the depressions that transport leaves when driving on a road with a soft surface - earth, clay, snow, sand. Surface marks are formed on paved roads (concrete, asphalt), on flat objects lying on the road, on the victim's clothes.
Surface marks, in turn, are subdivided into layering marks and delamination marks. Layering traces are formed when a trace-forming substance is transferred from the wheel to the road. Such traces are formed when a vehicle leaves the side of the road, country roads on a paved road. Peeling marks are formed when the trace-forming substance is transferred from the road surface to the wheel. Such marks remain when the tire of the wheel comes into contact with the spilled coloring matter on the road.
By visibility vehicle tracks are subdivided into visible, hardly visible and invisible. So, the trail of locked wheels is clearly visible on dry asphalt, but on an icy road it is almost invisible and its detection requires the use of appropriate technical means of forensic science and logical methods of modeling the event of a traffic accident.
Depending on the location of the changes on the trace-sensing object, traces can be subdivided into local and peripheral. Local footprint arises as a result of changes in the trace-perceiving object within the limits of its contact with the trace-forming object. The wheel cover leaves a mark, changing the soil within the limits of pressure on it, and the rest of the soil surface remains in the same state. Peripheral trace formed by changes that occur outside of the contact between the wheel and the road. So, outside of the contact, any substance can be layered or, conversely, a part of the substance can peel off.
Depending on the mechanism of trace formation traces can be divided into static and dynamic. The formation of these traces occurs at the moment when both objects (trace-forming and trace-perceiving) are practically at rest. Static trace is the rolling track itself. It is a series of imprints of a wheel tire, located side by side and forming, as a whole, one continuous imprint of a track-forming surface in an expanded form. Dynamic footprint formed as a result of braking, skidding, wheel slip. Braking tracks differ from static rolling tracks in that they are stretched, the tread pattern elements are lubricated, which is caused by the deceleration of the wheel rotation speed during braking and thereby the discrepancy between its speed of movement of the vehicle. The greater the discrepancy, the more lubricated the tread elements will be. If the wheels completely stop rotating until the vehicle comes to a complete stop (wheel blocking), thus the braking traces turn into skid marks ("skid"), that is, continuous smeared tracks, where individual elements are no longer distinguishable.
By the peculiarities of the relationship Vehicle tracks are subdivided into a track track and a separate track, which in turn is subdivided into a single wheel track and a twin wheel track. Separate trace is formed under such circumstances when the track formation conditions are unfavorable for the preservation of other vehicle tracks (other wheels). A motorcycle that does not have a side trailer leaves only a single trail when moving quickly on a flat road surface. Track track formed under conditions that are equally favorable for track-forming objects (wheels) located on both sides of the vehicle. The track track includes individual tracks and therefore everything that relates to working with a single track fully applies to tracks forming a track. In the track itself, there are traces of rectilinear movement, traces of a turn, traces of a turn with maneuvering, traces of parking.
Dragging marks. If you run over a person or any object, the vehicle can drag it along a certain distance. In this case, there may be dynamic drag marks in the form of smeared stripes. The length of the traces of dragging depends on the characteristics of the object being dragged, on the speed of the vehicle, and on the condition of the road. On a road covered with asphalt, traces of dragging may not appear, but on country roads and on the sides of asphalt roads they remain. Their study allows us to judge the nature of the road traffic accident, the place where the collision occurred, as well as the subjective reaction of the driver who continues to move.
Tracked vehicle tracks are formed by the tracks that make up the caterpillar. They remain in the form of two stripes, the distance between the centers of which corresponds to the track width. Track tracks allow you to determine the type and model of a combat vehicle or special vehicle. These tracks display general (the number of tracks on the track, the distance between the tracks, the nature of the tracks' relief) and specific (deformation of the edges of the tracks, differences in the distances between individual tracks) track signs, by which it is possible to identify the vehicle.
Runner tracks remain during the movement of horse-drawn sleds, snowmobiles or skis. Runner tracks refer to skid tracks formed by a plane, their dynamic character deprives them of clarity, that is, the signs that are displayed in the tracks, therefore their identification value is not as great as the tracks of tires and tracks. Common features include track width, runner width, and guide chute width. Terrain irregularities located at the ends of the runners can sometimes be displayed as private signs.
Along with the traces of vehicles, forensic significance is traces of horse-drawn wheeled transport. In practice, carts, arabas, two-wheeled carts are still used. Some of them are equipped with rubber tires, the tracks of which are not much different from those of vehicles. Most horse-drawn carts have wooden wheels with metal rims, on the trail of which a group affiliation can be established, and with a sufficient set of individual signs displayed in the tracks, a specific horse-drawn vehicle can be identified.
Forensic value traces of vehicles consists in the possibility of establishing by the subject of proving a number of important circumstances of a criminal event (road traffic crime, crimes against the person, against someone else's property - in cases where vehicles are used). In particular, it is possible to find out the mechanism of a road traffic crime or accident as a whole, and its individual elements.
So, the length of the brake track is determined by the speed of the vehicle before the start of braking, its braking and full stopping distance. On the track left on the road surface by a car tire (tread pattern, width of a treadmill), it is possible to establish its model.
On a number of grounds, it is possible to identify a vehicle by its tracks. These include signs caused by a defect in the tread, signs associated with the production of tires. With the use of anti-skid devices (spikes, chains, tracks), as well as accidental signs (foreign objects stuck in the grooves of the tread or embedded in the rubber).
Traces of engine oil, brake fluid, etc., left at the scene of the accident (for example, at the parking lot), may indicate the technical condition of some units of the vehicle.
The type and make of the car is determined by the width of the track and by the size of the base of the car. A number of signs indicate the direction of traffic.
The presence of cargo in the body of the car and its nature may be evidenced by its part, fragment, remaining in a collision or run over at the scene.
Clarification of these issues, which determine the forensic value of vehicle tracks, is carried out by the investigator during the inspection of the scene of the incident, while performing other investigative and other actions. So, in preparation for the interrogation of a suspect, the investigator can independently establish the approximate speed of the vehicle immediately before braking it. This is an element of the preliminary (pre-expert) investigation of the circumstances of the event and is aimed at creating a tactical advantage over the suspect at the initial stage of the investigation, in particular, at his very first interrogation.
The main part of the questions is to be clarified by specialists within the framework of transport-traceological, auto-technical and other examinations, the preparation of materials for which is entrusted to the investigator.
Fixation, fixation inspection results are carried out by describing in the protocol, making diagrams or plans, photographing, filming, as well as by making casts and copies of tire tracks.
First of all, even before the inspection of the scene of the incident and during it, it should be done. photography. Photographs may be taken depending on the nature of the incident and the circumstances of the case. the section of the road where the traffic accident occurred, a general view of the center of the accident site (car, corpse), wheel tracks, cargo. For these purposes, various methods of photography are used.
With the help of orientation and survey photography, a general view of the scene of the incident and its surroundings is photographed. This shooting is usually done from two opposite or more sides.
In the protocol of inspection of the accident site and its annexes, the following elements must be recorded:
1) road; areas of the accident site and objects on which traces of vehicles were found, with an accurate description of their location and features;
2) a vehicle;
3) traces of a vehicle;
4) signs indicating the direction of movement of the vehicle (if necessary);
1. When describing road section where the traffic accident occurred, the protocol of the inspection of the scene of the accident indicates the relief of the road, transverse and longitudinal slopes, the condition of the shoulders, ditches, roadbed, turns and rounding (if necessary), and also traces of lubricants and liquids used for vehicles are recorded , vehicle parts found at the site of the accident site, prints of numbers and vehicle assemblies at various objects.
2. Description in the protocol vehicle(passenger, cargo, tank, armored personnel carrier) implies the reflection in it of the following elements:
- the position of the vehicle relative to the carriageway, fixed landmarks, other means involved in the incident, the corpse;
- make, car model, year of manufacture, state number, body and cabin color, tire model, pattern type, residual depth protector;
- the technical condition of the transport (determined by the express method with the help of a specialist auto technician): brake system, steering, chassis, electrical equipment, instrument readings, position of light switch keys, position of gear levers, front axle engagement, main clutch (for tracked vehicles), condition of windshield, rear-view mirrors, triplex;
- damage on the vehicle, their nature and location;
- the presence and localization of foreign traces-overlays and their characteristics (peeling of the paintwork of another car, objects of biological origin: blood, brain matter, hair, etc.);
- cargo: presence, nature, position;
- the place of storage of the vehicle after an accident (indicating the person responsible for its storage).
3. When describing in the protocol of the inspection of the scene tire tracks the vehicle should be fixed:
- the type and condition of the road surface;
- the location of the tracks relative to fixed landmarks;
- the type and number of tracks;
- the width of each treadmill;
- the depth of the volumetric traces;
- track size;
- the structure of the tread pattern, the nature of the imprints of the features of the tire surface;
- car base;
- the length of the braking track;
- signs of the direction of movement;
- the way of fixing, removing and packing the trace.
Brake track length measured with a tape measure with centimeter divisions. In this case, the beginning of the track is determined by the hardly visible signs left by the car tire in the initial stage of braking.
It should be borne in mind that tread rubber particles and other elements that form a skid track on the road surface are washed off over time by rain or eroded, as a result of which the length of the braking track decreases. So, in 1-2 hours, the braking track on the asphalt concrete surface can become shorter by 0.2-0.3 m.
Treadmill width is measured perpendicular to its longitudinal axis and along the bottom of the track, if it is volumetric. There may be slight differences (10-15mm) between treadmill width and tire tread width, depending on tire pressure and vehicle load.
Track– these are the tracks left on the road by the tires of the right and left wheels. Measurements are made between the centers of the tracks, the results of which are to be entered into the inspection protocol.
4. When a vehicle moves on the road, various materially fixed changes take place, by which it is possible to judge the direction of movement of transport, the direction of movement is determined by signs in the tracks of the wheels and by other signs on the road.
Signs of the direction of movement and parking space:
1. When driving on loose soil, a fan of soil particles is formed along the edges of the wheel track, the acute angle of which is directed in the direction of movement.
2. When moving through puddles, the dirt tracks will weaken and disappear as you move, and splashes of water and dirt are fan-shaped in the direction of travel.
3. Drops of liquid falling from a vehicle have an elongated shape (round with a narrowing), the sharp end of which is directed in the direction of movement.
4. When driving on tall grass, its stems tilt in the direction of movement, and when moving on low grass, when slipping, the stems tilt in the direction opposite to the movement.
5. When moving a branch, a stick breaks, forming an angle open to the direction of movement.
6. When moving on the ground, the stone is shifted in the direction of movement, and the notch from the stone remains on the side opposite to the movement.
7. When braking and skidding on soft ground, the soil shifts in the direction of travel.
8. The sharp corner of the tread pattern of off-road tires is directed in the direction opposite to the direction of travel.
9. The toe angle of the front and rear wheels at the beginning of the turn is greater than the toe angle at the end of the turn.
10. When braking, the skid trail sharply increases in the direction of travel and abruptly breaks off.
11. The tears on the victim's clothes from the protector are directed in the opposite direction.
12. The parking place of the car, among other signs, can be determined by the traces and stains of fuel and lubricants, water, brake and coolant.
5. If the accident is fatal, an inspection should be performed corpse with the participation of a forensic expert. When examining a corpse, the localization is recorded in the protocol of the inspection of the scene of the incident. various damages on the body of a corpse and their shape is described. In addition, the corpse's clothes are carefully examined, their condition and the traces on it (for example, traces of the surfaces of various parts of the vehicle - bumper, fender, wheel protectors, etc.).
The recording of the course and results of the inspection of the place of the road traffic accident is also carried out by charting, which is an attachment to the inspection protocol, but at the same time allows you to more clearly represent the situation of the incident.
It is recommended to record the progress and results of inspection of the accident site using video filming with the subsequent production of a video film. Video filming allows you to show not only the shape, size, relative position and other features of objects, but also to reproduce certain actions. It is preferable to use video filming in cases where the place of a road traffic accident is a significant territory, as well as for recording any events related to an accident (for example, extinguishing a burning car, lifting an overturned car).
The main technique for fixing and removing traces-mappings of vehicles is modeling by making casts. For this, conventional means of modeling volumetric traces are used, for example, gypsum, silicone paste "K", paste "U-1".
If at the scene of an accident there are volume traces , in which the features of the trace-forming object are displayed, plaster casts are removed from them.
Fixing traces on loose soil, in the sand is produced with the help of bonding agents. In practice, for these purposes, synthetic resins are widely used, which are mixed with rapidly volatile solvents and are applied by spraying to the track, due to which the latter, having obtained sufficient strength, can be removed from the soil without damage. These compositions include a 6% solution of perchlorovinyl resin, dissolved in acetone. An effective means of fixing traces in loose substances is hairspray in aerosol cans. After treatment with varnish and complete drying, the trail can be removed after 20-40 minutes. Such a trace remains for a long time in its natural form, which has a significant advantage over casts that fix the trace in a mirror image.
Surface marks transports are fixed by transferring them onto a sticky substrate, for example, onto large-format sheets of glossy photographic paper, which is moistened and is superimposed on the track with an emulsion surface and pressed tightly against it. Then the photographic paper is separated from the trail and placed with the emulsion up to dry. If black paper is needed to copy a trace, the photo paper is illuminated, developed, fixed and washed. Also, surface traces are transferred to sanded rubber sheets with a thickness of 3-4 mm.
Overlay traces, arising on a vehicle or left by a vehicle on other objects as a result of an accident are seized, if possible, together with the investigator, or separated from the object and packed in accordance with the rules for the seizure of microparticles.
Footprints-objects with traces of the vehicle displayed on them, as well as objects separated from the vehicle, are removed from the scene of the incident entirely, listed in the protocol and attached to the case as material evidence.
If available at the scene traces of fuels and lubricants their samples are taken and placed in sealed glass vessels.
Talking about research traces found at the scene of an accident do not mean laboratory methods, but techniques available to the investigator. Having found a tread mark, the investigator examines its design, trying to determine by it the brand of the car that left this mark. This is already research work, the results of which can significantly affect the course of further investigation.
The investigator, having data on the length of the braking track, the coefficient of adhesion, the condition and nature of the road surface, can use them for preliminary (pre-expert) determination vehicle speed immediately before applying braking, which in turn will allow him to more substantively investigate the crime.
First, the approximate speed of the vehicle before braking on the road without longitudinal slope can be determined using the following formula:
V – vehicle speed,
f- coefficient of adhesion of tires to the road (in calculations it is usually taken 0.6),
St- the length of the stopping distance,
254 is a conventional mathematical unit.
Secondly, an idea of the speed of the vehicle before braking with approximate accuracy can also be obtained using reference data.
In forensics, concepts differ vehicle braking distance and full stopping distance.
Under braking refers to the distance the vehicle travels from the moment the brake pedal is pressed to a complete stop.
Full stopping distance - the distance traveled by the car from the moment the driver began to react to the danger to a complete stop. The stopping distance is determined by the formula:
t 1 – driver reaction time to danger- the interval from the moment of the appearance of the signal about the danger to the beginning of the action on the brake pedal of the car. This time depends on the qualifications, experience, age, health of the driver and other factors.
t 2 – brake response time... During this time, the pressure from the main brake cylinder (or valve) is transferred to the wheel cylinders (brake chambers) and a gap is sampled in the brake drive parts. After the time t 1 + t 2 the brakes are applied and the vehicle speed starts to decrease. Time t 2 is taken in calculations for vehicles with a hydraulic brake drive 0.2 seconds, with a pneumatic drive 0.8 seconds.
Ke- vehicle operating factor (deterioration of vehicle systems, quality of adjustment, etc.). Accepted for trucks 1.4, for cars - 1.0.
V- vehicle speed.
f - coefficient of adhesion of tires to the road.
1. Direction of the corners of the tread pattern in the tracks of off-road tires. 2. Location of dust near the track. 3. The location of the ends of the poles, broken when moving. 4. The location of the gap near a stone pressed into the ground when moving. 5. The ratio of the angles of divergence and angles of convergence of the tracks on the bend. 6. Relief of the bottom of the track. 7. Drops of liquid that have fallen from the vehicle.
Rules for describing footprints (shoes) in the protocol.
When a track (shoe) track is found, it is described:
Location of detection with reference to two landmarks;
The nature of the trace-perceiving surface;
The type of traces in accordance with their traceological characteristics and trace-forming surface;
Appearance substances that form the surface traces of shoes (color, consistency, etc.);
What part of the bottom of the shoe or bare feet is displayed in the footprints;
The dimensions of the tracks;
Features displayed in separate tracks;
Track elements;
Methods and technical means of fixation, removal and packaging.
An approximate fragment of the protocol of the inspection of the scene of the incident with a description of the "path" of footprints:
“... In a vegetable garden on plowed black soil, a track of footprints was found, which starts from the eastern corner of the house and is directed northward to the gate in the fence. The track is 25 meters long, and consists of voluminous depressed shoe tracks, which were displayed quite clearly. At the time of inspection, the surface of the tracks is slightly moistened. Elements of the track track: the length of the step of the right leg - 66 cm, the length of the step of the left leg - 68 cm, the angle of rotation of the right foot - 7 degrees, the angle of rotation of the left foot - 11 degrees - the width of the step - 10 cm. The 5th shoe mark from the right foot and 7th shoe mark from the left foot. The size of the footprint on the right foot: the total length of the footprint is 30 cm, the largest width of the intermediate part is 11 cm, the smallest width of the intermediate part is 6 cm, the length of the heel is 8 cm, the width of the heel is 7.5 cm, the depth of the track in the toe area is 2 cm, in the intermediate part - 0.5 cm, heel - 1 cm.In the footprint of the shoe from the left foot, the depth in the toe area is 1 cm, in the intermediate part - 0.5 cm, heel - 2 cm, the rest of the size is the same as and in the footprint of the right foot. The shape of the toe in the footprints is round, the front edge of the heel is concave, the outsole and the intermediate part of the sole form one whole. In the middle part of the outsole track there is a relief pattern in the form of round recesses 1 cm in diameter, up to 0.3 cm deep, arranged in rows running across the outsole. The footprint of the heel displayed 4 transverse depressed stripes 0.8 cm wide, 0.2 cm deep, the distance between them is 0.5 cm. extension ring No. 1 and a flash lamp in oblique lighting. From the two described tracks, sketches were made at a scale of 1: 1 on sheets of light dacto film by tracing the contours of the tracks and patterns of the sole. Plaster casts were made from the two described tracks, to which tags with explanatory inscriptions were attached. The casts are packed in cardboard boxes, the boxes are tied with light brown twine, the ends of which are sealed with a wax seal ... "
An approximate list of questions when appointing a traceological examination of a "track" of traces and a single footprint of a shoe:
Are the traces of bare feet found during the inspection of the scene suitable for identification?
Didn't such a person leave traces of bare feet?
Is the discovered footprint a footprint of a shoe submitted for research?
Did the same or different shoes leave marks?
What type of footwear belongs to, traces of which were found at the scene of the incident, what features does it have?
How did the person move, whose footprints were found at the scene of the incident (slow, fast pace, running)?
What conclusions can be drawn from the existing footprints about the characteristics of the person who left them and his condition (approximate height, gender, complexion, shoe size, physical disabilities)?
Is the track of footprints left by a specific person?
Rules for describing wheel tracks in the protocol.
When wheel tracks are found, the following is described:
The type and condition of the surface on which traces have been left (for example, wet asphalt, dry sandy soil, snow);
Track type;
Location in relation to fixed landmarks;
The width of the running part of the tread of the wheels (tracks, runners);
Track width;
Vehicle base;
Skid track length;
Maximum depth of volumetric traces;
Tread pattern structure;
The shape and location, as well as the dimensions of the prints of the features of the tire surface;
The distance between two prints of the same track feature (tire defect, stuck stone, etc.);
Signs of the direction of movement of the vehicle (direction of spray marks, position of the ends of broken branches, etc.);
Method of fixing and removing wheel tracks.
An approximate fragment of the protocol of the inspection of the scene of the incident with a description of the tracks of the wheels of the car:
“… 20 m from the post with the sign“ p. Urozhainy "in the direction of the village on the right side of the highway, on the clay soil, bulky tire rolling marks were found. The tracks leave the road at an angle of 25 degrees, then run parallel to the asphalt and come out onto the asphalt at an angle of 15 degrees at a distance of 47 m from the post. The outer track is 2, 2 m from the edge of the asphalt in the most distant part and from the ditch - by 0.5 m. The total number of tracks on the roadside sections adjacent to the asphalt at the beginning and end of the tracks is 4. The width of the treadmill of each track, measured in several areas is 145 mm, the largest depth of volumetric traces is 90 mm. The track width of the vehicle is the same for the front and rear wheels and equals 1,440 mm, the base of the vehicle, measured in the section with the greatest curvature of the tracks, is 2,400 mm. In all tracks, tire tread patterns were displayed, consisting of arrow-shaped elements located along the axis, 20 mm wide and 30 mm long with two parallelograms with dimensions of 36x24 mm and 30x36 mm adjacent to them at an angle of 45 degrees. A detailed examination revealed a feature measuring 10x15 mm in the form of a bulge in the track of the left rear wheel, repeating in the track every 240.5 cm. The bottom of the tracks on clayey soil has a sawtooth structure, the flat sides of the ground areas are turned towards the village of Urozhainy. Wheel tracks were photographed using linear panorama photography. From the traces, schematic sketches were made at a scale of 1: 1 by redrawing in the light. A plaster cast 45 cm long was made from the trace of the left rear wheel with the existing feature ... "
An approximate list of questions when appointing a traceological examination of vehicle tracks:
Are there any traces found at the scene of the incident? undercarriage(wheels, tires, skids) of this vehicle, or some other part of it?
What type (type) is the vehicle, whose traces were found at the scene?
In what direction was the vehicle moving, judging by its tracks?
What is the model of the diffuser, the fragments of which were removed during the inspection of the scene? What vehicle is it for?
Traces at the accident site can be divided into the following:
- vehicle wheel tracks
- traces (point and linear) of vehicle parts on obstacles with which they interacted during an accident
- traces of parts, parts separated from the vehicle, as well as various kinds of substances (bulk cargo, oil, etc.)
- traces of victims
- traces on the vehicle
Traces at the accident site, left over from the wheels of the car, can be traces of rolling, braking, skidding. Traces of this kind indicate the trajectory and direction of the vehicle during an accident.
Rolling marks
On snow, wet sand, clay, etc. these tracks represent the volumetric imprints of the tread pattern.
Imprint Is the mark left by the tread on a soft surface when the wheels of the vehicle are free to rotate. The tread marks are clearly visible along and across the track.
The tread pattern remains on the asphalt pavement in the form of a layer of dust, dirt, and other particles after the vehicle moves along the side of the road, on a dirt road, when moving from wet to dry areas.
If particular signs are displayed in the tracks, in this case it is possible to identify a specific vehicle wheel (individual identification).
Braking (sliding) traces
On dry asphalt surfaces, this is a lane oiled in the direction of travel, and on unpaved surfaces, a loosened furrow.
Slip marks(skid) - these are the lanes left on the road by tires of braked (non-rotating) wheels. If the tire slides in the plane of the wheel, then its track can be easily distinguished from the imprint, since the tread pattern, although not visible across the track, can leave a certain number of longitudinal lines. When the tire slides parallel to the wheel axle, the track width is equal to the length of the tire-to-road contact zone. In this case, no features of the tread pattern are visible.
Influence of redistribution of car mass on slip marks. The redistribution of mass along the axles when braking a vehicle often makes it possible to determine which wheels left a slip mark - front or rear.
If the tire pressure corresponds to the manufacturer's recommended pressure, then during normal driving, the vertical load in the contact area of the tread with the road surface is evenly distributed. Under heavy braking, increasing the load on the front wheels has the same effect as lowering the tire pressure, and reducing the load on the rear wheels is tantamount to the effect of increased pressure. The skid marks of the front wheels when the tires are overloaded are lighter in the center and darker at the edges. This is more common with radial tires than bias tires.
The tire tracks of the unloaded rear wheels are lighter, with clear longitudinal lines from the tread, which can be used to determine the length of the track, and with slightly blurred edges.
Rear wheel skid marks... In cases where there are traces of sliding of only the rear wheels, you must first find out if this is due to the use of one hand brake (which often leads to a skid). If so, then the driver's motives should be clarified: either the main braking system is faulty, or the driver's foot slipped off the pedal and use hand brake was a natural reaction to this. Therefore, depending on the circumstances, it may be necessary to experimentally determine the traction force developed in road conditions by one handbrake. This requires an identical emergency vehicle and with the same load.
However, if all wheels were braked, then it would be correct to conclude that the tracks were left due to the redistribution of mass, as a result of which the force that blocks the rear wheels was reduced. To confirm that the brakes on the front wheels are working properly, the vehicle should be checked.
It should be noted that blocking only the rear wheels during emergency braking is a danger, to reduce which many vehicles, especially front-wheel drive, are equipped with safety valves that limit the pressure in the hydraulic brake of the rear wheels. However, these devices are not always reliable, especially on low grip roads.
Slipping marks
The origin of tire slip marks can vary, but in all cases they are the result of the simultaneous sliding and rotation of the wheels. Below is the description different types traces of slippage left at the scene of the accident.
Slip marks from a flat tire are very similar to those of the front wheels. However, close inspection reveals small stone and sand scratches along the track, while in a flat tire track some scratches are oriented laterally. In addition, a flat tire track is usually wavy, and an off-alignment of its trajectory often indicates a controlled movement of the vehicle.
Cornering traces remain when the wheels rotate freely, but the tires slip laterally due to centrifugal force. Redistributing the load to the outer two wheels in relation to the pivot center usually results in traces of slippage from only those wheels, although on very slippery surfaces this usually occurs from all wheels.
The rear wheel tracks of a conventional vehicle during normal cornering are always inside the front wheel tracks, but this rule is often violated during skidding. Often, the slip mark is only a narrow strip that is similar to one side of the tire slip mark. front wheel... Such a trace arises due to the fact that the tire, deforming, as it rolls in the lateral direction under the action of centrifugal force.
Traces of slippage during deceleration occur during intensive braking on the non-slip surface of the wheels without blocking and before blocking. They always precede the traces of sliding and are best seen by small scratches from pebbles and sand grains oriented along the direction of travel. It is usually impossible to determine where the slip trail ends and the slip trail begins. Both of these are included in the measured total braking track.
Traces of slippage during acceleration occur when the tractive effort on the drive wheels is too great. It is possible to distinguish them from deceleration marks only with a very careful examination. When accelerating, pebbles and grains of sand are pulled out of the tire by the tire and, leaving scratches, are thrown back, while when slowing down, scratches appear as a result of particles being pressed into the road surface and their subsequent movement.
Crash slip marks indicate the exact location of the collision and appear as stripes or stripes across the vehicle's line of travel. Traces of slipping of locked wheels under the impact of an impact in an accident noticeably change direction from the original. A free-wheeling wheel, when struck, can momentarily lock up and leave a short skid mark on the road that can be detected upon close inspection.
Measurement and fixation of traces of sliding and slippage. The necessary data for a reliable assessment of the speed of vehicles involved in road accidents is obtained from the inspection and measurement of tire tracks on the road. The result of the investigation largely depends on the thoroughness of these operations.
Determination of the belonging of tracks to a specific vehicle. It is very important to establish which particular vehicle the tracks belong to. Often the driver admits that the tracks were left by his car, or witnesses say this. Sometimes a witness's confirmation of a squeak of slipping tires is sufficient to identify the tracks. If there are no witnesses of an accident, it is possible to detect signs of tire slip with a thorough examination, however, when the vehicles are removed from the accident scene, these signs quickly disappear, since the mass of rubber particles left on the road is very small. If more than one vehicle was involved in the accident, then the dimensions of the vehicle track help to establish the belonging of the tracks.
Start and end of the track. The point where the tire began to slide is easier to establish if the track is viewed along the track from a distance at a low angle. In this case, you should use the help of an assistant who would mark the indicated point with chalk. To check the accuracy of measurements, the observer needs to repeat the procedure, changing places with an assistant.
Gaps in the slip track. Discontinuities in the skid track can be caused, first, by the separation of the wheel from the road surface. In this case, the gaps are very short and numerous. This is caused by the low axle load, which causes the wheels to bounce on bumps in the road. Before and after each rupture, the braking effect of the wheel is very high, which compensates for its loss during the absence of contact between the tire and the road. Therefore, the strokes of the trail and the gaps between them are measured together, although the length and location of each stroke should be indicated. The calculation uses the full length. Secondly; Tire track tears can be caused by intermittent brake pedal depressions. They are usually longer than tears caused by the wheels breaking off the road. The distances between the visible parts are quite large, since in an extreme situation the driver is not able to stop and resume braking so often that the resulting intermittent trail could be similar to the image created by the periodic separation of the rear wheels. In this case, each segment of the track of this wheel must be measured separately, and in the calculations, use the actual sum of these segments.
Straight-line sliding. A straight-line slip is a slip in which the track of at least one rear wheel does not go beyond the strip located between the front wheels, while the tracks may be slightly curved.
To carry out the calculations, it is necessary to measure the longest track left by one of the wheels, since it is obvious that all of them are braked while at least one of them is sliding along the road. Indeed, if the wheel is not yet locked, and the other has already begun to slide, the braking force on it will be the same or even greater than on the locked one.
Such braking is typical not only for motorcycles, since the brakes on their wheels are independently driven, but also for other vehicles.
Skidding. Skid marks are curvilinear sliding marks on the surface of which there are tracks located at an angle to the boundaries of the track, left by the protrusions of the tread pattern.
In traces of braking and skidding, as a rule, the identification signs of a wheel are not displayed.
A sign of slipping with a skid is considered to be the exit of the rear wheel tracks beyond the track of the front wheels of the vehicle. In this case, the vehicle, along with forward movement, is displaced sideways or rotated around a vertical axis.
If there are traces of sliding with a skid, it is necessary to measure the total length of each of them (taking into account their curvature) and determine the average length, which is used in further calculations. The fact is that at some moments in time, one point of the vehicle can almost stop, while others rotate around it, as a result of which the sliding path of some wheels turns out to be long. This averaging method should only be used when the load on the rear and front wheels is approximately equal, which is typical for cars and light trucks, but not for tractors with semi-trailers and trucks with twin rear wheels. In some cases, to calculate the speed, it is sufficient to fix the part of the track where the straight sliding occurred, without taking into account the place where the side slip or rotation of the vehicle began. The nature of the pattern appearing on the road depends on the ratio of the rotation speeds and the rectilinear movement of the vehicle. This means that two tracks cannot be exactly the same.
Changing the adhesion of the road surface along the track
Often, the trail left by a vehicle runs along sections of the road with different surface qualities, especially when braking starts at an intersection and ends behind it. In such cases, it is important to measure the length of the track within each section, i.e. from the beginning of the boundary between areas with different surfaces and from this boundary to the end of the track. This is necessary in order to separately calculate the lost vehicle speed in the initial and last braking section and thus accurately determine the speed before braking.
Motorcycle tracks
Interpreting motorcycle tracks is difficult because each wheel is braked independently of the other. An experienced motorcyclist always applies intermittent front wheel braking before applying the foot brake. In this case, the motorcycle tracks are examined in the same way as the braking tracks of other vehicles, when it is known that each wheel was locked or braking occurred in a mode close to locking. If only the rear brake was used, then the removal of the vertical load from the rear wheel due to the redistribution of mass results in a lengthening of the braking distance, from which it is difficult to determine the actual loss of speed.
It can be assessed only with control braking by one rear brake on a motorcycle of the same brand, and the driver's weight must be equal to the one involved in the accident. It is important that this experiment is carried out by an experienced motorcyclist as it is very difficult to brake the motorcycle to a complete stop when the rear or front wheel is locked.
Damage to the road surface after a collision
The vehicle, interacting with various obstacles in the course of an accident, leaves on them surface and depressed (point and linear - dynamic) traces. The study of these traces makes it possible to solve identification and a number of diagnostic tasks, which makes it possible to clarify the place of contact of the object with the vehicle and the direction of its movement after such interaction.
This type of footprint can be grouped as follows:
- scratches, layers, tracks, scuffs on the carriageway, formed by damaged parts of the vehicle (rods, levers, engine protection casing, etc.)
- damage to the road surface in a collision. Impact tracks are usually short, but sometimes deep due to tremendous forces developing during the collision. Sometimes, parts of the vehicle will break off on impact and go deeper into the road surface. An example of this is the gimbal, which often collapses in an oncoming collision. Such potholes can often identify a specific vehicle, and sometimes they provide the only way to determine the exact location of the vehicle at the time of impact.
- scratches, tracks left by the vehicle wheel rim when the tire is damaged and driving it on a tire with insufficient pressure
- scratches, layers of paintwork (LCP) formed when the vehicle rolls over
Scratches as marks are very important for determining the position of the vehicle during a collision and especially its movement after a collision. Similar traces can appear when removing vehicles from the accident site. They can be excluded from consideration by interviewing, if necessary, the persons operating after the emergency evacuated equipment.
Damage showing the vehicle's travel path after a collision is often in the form of long, thin scratches drawn by damaged parts that touch the road surface (e.g. suspension parts, after a wheel break, body angle, etc.) Sometimes damage can be in the form of abrasions, short, flat or wide scratches that appear due to the large area of contact of the car with the road, for example, when its roof slides.
A careful study and comparison of damage and coating material with the condition of the body and vice versa, can be used to determine not only the path of movement of the vehicle, but also the relative position of vehicles.
Traces in the form of particles and LPC macro-particles separated from the vehicle are of great importance for the investigation of road accidents:
- debris of small particles
- loose soil or soil upon impact at the time of collision or collision. The location of the finest particles or dust, combined with other indications, indicates the location of the collision.
- separated particles and microparticles of paintwork help to determine the place of contact of the vehicle with an obstacle and the direction of movement of the vehicle when it is thrown away (their location may change under the influence of the wind)
- fragments of glass of headlights, sidelights, rear-view lamps. By the areas of their dispersion, it is possible to approximately establish the trajectory of the vehicle after contacting and determine the place of its stopping (in the absence of the vehicle at the scene of the incident)
- traces exhaust gases... Using them, it is possible to establish the place where the vehicle stops, including relative to the boundaries of the carriageway.
Traces left by victims:
- traces of rubber shoes when hitting are noticeable on a concrete roadway, some are well detected on snow and soft soils. Such traces, due to the fact that they may be located at some distance from the place of detection of other collision marks, are extremely rarely recorded. Shoe marks accurately indicate the place of collision and the direction of the applied force
- traces of dragging the victim's body. On the asphalt surface, these are traces of blood, and mixed with asphalt dust or dirt, they look like stripes - dust (dirt) exfoliation
- discarded personal belongings that the victim had (bag, groceries, etc.). They can be located both directly at the collision point, and at some distance from it along the inertial movement of the vehicle.
Traces on the clothes and shoes of the victims
Traces of vehicle contact with clothing and footwear of a pedestrian upon collision or crossing
- prints (point marks) of headlight rims, cladding, decorative and other details of the front of the vehicle in the form of layers of dirt, wrinkles in clothing fabric - they can be used to identify the vehicle
- cuts of clothing with headlamp glasses in the places of contact in the form of linear and point damage to the material - they determine the relative position of the victim and the vehicle
- splashes of paintwork particles exfoliated from the vehicle on the pedestrian's clothes
- interspersed with microparticles (fragments) of glasses, headlights - they can be used to identify the vehicle, establish the relative position of the vehicle, and the pedestrian relative to each other
- layering of dust, dirt in the form of prints of the tire tread pattern, which may be somewhat distorted due to displacement of the fabric when moving the body. Such tracks are suitable for group identification of a tire and a vehicle on which tires of this type can be installed, as well as for determining the direction of its movement.
- tears and deformations of clothing fabric
Sliding tracks on the road surface:
- layering of dust, dirt, abrasion of the surface layer and through damage resulting from abrasion of the clothing material when moving the body on a flat surface of the road surface (asphalt, concrete). From such traces, it is possible to establish the fact of dragging the body after falling onto the roadway and the direction of displacement (arcuate folds are always directed with their convex part in the direction opposite to the direction of displacement)
- tears in the clothing material when moving the body on uneven road surfaces. The direction of movement is determined by the location of the angular breaks (the angle is open forward, in the direction of travel)
- traces of rubbing on the soles of shoes. According to such traces, as noted earlier, it is possible to establish the direction of displacement of the leg at the moment of contact between it and the vehicle - by the location of the wear and the direction of the tracks on the sole
Traces of contact of parts of the vehicle interior with passengers and the driver
This group of traces includes prints of the pattern of the pedals on the soles of the driver's shoes, the pattern of rugs on the soles of the shoes of passengers and the driver, traces and damage on various parts of the interior of the passenger compartment (deformation of the steering wheel, dashboard, windshield, blood stains, etc.), location of persons after an accident.
In the production of a comprehensive forensic and autotechnical examination, having studied the traces inside the car, the direction of the action of forces on the persons who were in it at the time of the accident, as well as the nature bodily harm, you can establish the relative position of the persons who were in the vehicle at the time of the accident.
Traces arising from a collision of a vehicle
Much information can be gained from examining the damage and end position of a vehicle. The degree of corrosion of the body (i.e. its condition), differences in body structure, and the multiple points at which an impact may have occurred, make it difficult to calculate the forces that caused specific damage. It should be noted that even at relatively low speeds there can be significant damage.
Damages are classified according to various criteria that require careful study in each case. First of all, the investigator must determine whether the car was damaged before the collision or during it, or as a result of its forced movement after the accident, or when the victims were released from the car. Old damaged areas are usually covered with rust or dried road dirt. If the damage is the result of an accident, it can be categorized as follows:
- traces of direct contact of deformed parts of the vehicle when they come into contact. Following such traces, it is possible to roughly imagine the relative position and mechanism of interaction of the vehicle during an accident
- prints of individual areas, parts of one vehicle on the surface of another. Having identified them, it is possible to establish the relative position of the vehicle at the time of their collision, as well as to identify the trace-forming object
- scuffs, scratches, etc. resulting from vehicle contact. Such traces contain displays of macro- and micro-relief, which are necessary to identify the vehicle with which a tangential collision occurred, to establish the fact of vehicle movement in a cross-collision, to determine the direction and relative speed of its movement in an accompanying collision.
- similar marks on the deformed lower parts of the vehicle in contact with the carriageway. They can be used to judge the direction of movement of the vehicle after a collision, to clarify the place of collision, taking into account the location of the traces left by these parts at the scene
Traces that appear when the vehicle hits stationary objects:
- damage to roadside objects such as lamp posts and trees, embankments and fences. They may be at some distance from where the vehicle stopped after an accident, and therefore they can be easily overlooked. Based on such damage, it is possible to establish the path of the vehicle before the collision and obtain information about the causes of the accident, determine the point from which the vehicle left the carriageway. When inspecting the roadside area, pay attention to possible tire prints and other marks. It should be borne in mind that the vehicle after colliding with one stationary object or more may noticeably turn around, which makes it difficult to determine the initial direction of its movement. However, you should be extremely careful when identifying vehicles involved in an accident and traces, since some objects, for example walls near a narrow road or passive safety equipment, have traces of previous collisions.
- layering of vehicle paint on the surface of a stationary object. According to them, it is possible to establish the group belonging of the car paintwork
- scratches, imprints of vehicle parts on the surface of a stationary object. In the presence of such traces, you can determine the direction of movement of the vehicle, identify the trace-forming object
- layering of vehicle microparticles and barriers. These traces are used to establish the fact of their contact interaction (the problem is solved in a complex way with the participation of an expert-trace specialist)
Footprints when colliding with pedestrians:
- deformation of the parts of the vehicle that struck the blow (dents on the hood, fenders and other parts of the vehicle, damage to the front pillars, windshield). From such traces, one can judge the location of the pedestrian in relation to the vehicle's lane, and taking into account the location of the vehicle wheel tracks, specify the place of collision
- prints of the texture of clothing fabric on the plastic parts of the vehicle (bumper), traces of blood, the victim's hair. Using them, you can establish the fact of a collision, identify the vehicle that made the collision
- traces of layers and delamination on the side of the vehicle. Such traces indicate the fact of contact interaction of the vehicle with a pedestrian during a tangential impact
Traces appearing on the vehicle when it rolls over:
- deformation of the roof, pillars, doors. According to them, the fact of overturning of the vehicle and its direction of movement are established
- traces of friction on the surface of the roadway (cuts, paint peeling). These marks indicate the direction of overturning and the change in position of the vehicle when moving after overturning.
- destruction of glass, damage to doors. Using them, it is possible to clarify the mechanism for the loss of persons and objects from the vehicle.
Traces that appear before the accident, when the vehicle hits hard and sharp objects on the road:
- tire damage when hitting sharp objects (cuts, punctures)
- damage to the wheel disc and suspension when the vehicle hits an obstacle on the roadway (foreign objects, potholes)
Based on the indicated traces, it is possible to clarify the mechanism of the accident, taking into account the changes in stability and controllability of the vehicle caused by damage (if it is previously established that they occurred immediately before the accident).
The possibility of resolving the issue of the place of collision of a vehicle by an expert method and the accuracy with which it is possible to determine the location of each vehicle on the road at the time of the collision depend on what initial data about the circumstances of the accident the expert has and how accurately this place is determined.
To determine or clarify the location of the vehicle at the time of their collision, the expert needs the following objective data:
About the traces left by the vehicle at the scene of the accident, about their nature, location, length;
About the traces (tracks) left by objects thrown away in a collision: parts of the vehicle that separated on impact, a load that fell out, etc .;
About the location of areas of accumulation of small particles that have separated from the vehicle: earth, dirt, glass fragments, areas of splashing liquids;
About the location after the collision of the vehicle and objects thrown in the collision;
About vehicle damage.
In most cases, the expert has only some of the listed data.
It should be noted that, no matter how conscientiously the situation at the scene of the accident was recorded by persons who do not have experience in conducting auto-technical examinations (or do not know the methods of expert research), omissions cannot be avoided, and they often cause the impossibility of determining the place of collision. Therefore, it is very important that the inspection of the accident site is carried out with the participation of a specialist.
When inspecting and examining the scene of an accident, first of all, you need to record those signs of an accident that may change during the inspection, for example, traces of braking or skidding on wet surfaces, traces of moving small objects, tire tracks left when driving through puddles or leaving roadsides, areas of scattered earth during rain. The location of the vehicle should also be recorded if it is necessary to move them to provide assistance to the injured or to clear the roadway.
Determination of the place of collision in the tracks of vehicles
The main signs by which you can determine the location of the collision are:
A sharp deviation of the wheel track from the initial direction, which occurs when an eccentric impact on a vehicle or when hitting its front wheel;
Lateral displacement of the track resulting from a center impact and a constant position of the front wheels. With a slight transverse displacement of the track or its slight deviation, these signs can be detected by examining the track in the longitudinal direction from a low height;
Traces of lateral displacement of unlocked wheels are formed at the moment of a collision as a result of lateral displacement of the vehicle or a sharp turn of its front wheels. As a rule, such traces are hardly noticeable.
Termination or rupture of the skid trace. Occurs at the moment of a collision due to a sharp increase in load and violation of wheel blocking or separation from the road surface;
The skid track of one wheel that was hit has jammed it (sometimes only for a short period of time). In this case, it is necessary to take into account in which direction this trail was formed, based on the location of the vehicle after the accident;
Traces of friction of vehicle parts on the coating when its chassis is destroyed (when a wheel is torn off, suspension is destroyed). They start mainly near the collision site;
Traces of movement of both vehicles. The collision point is determined by the intersection of the directions of these tracks, taking into account the relative position of the vehicle at the time of the collision and the location of the parts on them that left traces on the road.
In most cases, the listed signs are hardly noticeable, and when examining the scene of the incident, they are often not recorded (or they are not recorded accurately enough). Therefore, in cases where the precise determination of the location of the collision site is essential for the case, it is necessary to conduct an expert study of the accident site.
Determining the location of the collision by traces left by discarded objects
In some cases, the location of the collision can be determined by the direction of the tracks left on the road by objects thrown in the collision. Such tracks can be scratches and successive pits on the road left by parts of the vehicle, motorcycles, bicycles or cargo that has fallen, as well as traces of dragging the bodies of drivers or passengers who fell out of the vehicle at the moment of impact. In addition, traces of the movement of small objects remain at the scene of the incident, visible on snow, soil, dirt, dust.
First, the objects that are discarded move in a straight line from the place of their separation from the vehicle. Subsequently, depending on the configuration of the object and the nature of its movement along the road surface, a deviation from the initial direction of movement may occur. When gliding cleanly, on a flat area, the movement of objects remains almost straight to a stop. When rolling while moving, the direction of movement may change as the speed decreases. Therefore, the place of collision of the vehicle can be determined by the tracks of the discarded objects, if there are signs that these objects were moving in a straight line or the trajectory of their movement is visible.
To determine the location of the vehicle at the moment of collision, along the tracks of thrown objects in the direction of the likely place of collision, lines should be drawn - the continuation of the direction of these tracks. The place of intersection of these lines corresponds to the place of impact (the place of separation from the vehicle of objects that have left traces).
The more traces left by discarded objects are recorded, the more accurately you can indicate the place of collision, since it becomes possible to select the most informative traces, discarding those that could deviate from the direction of the collision (for example, when objects are rolled, that they were left, when moving objects through irregularities, when the beginning of the track is located at a great distance.
Determination of the place of collision by the location of objects separated from vehicles
It is impossible to find out the place of collision of the vehicle by the location of any parts, since their movement after separation from the vehicle depends on many factors that cannot be ignored. The area where the maximum number of parts thrown back in a collision is located can only roughly indicate the place of the collision. Moreover, if the place of collision is determined by the width of the road, it is necessary to take into account all the circumstances that contributed to the one-sided displacement of the discarded parts in the transverse direction.
A sufficiently accurate collision point is determined by the location of the ground, which crumbled from the lower parts of the vehicle at the moment of impact. In a collision, earth particles crumble at high speed and fall on the road almost at the point where the impact occurred.
Most of the soil is separated from the deformed parts (surfaces of the fenders, mudguards, the bottom of the body), but if the car is heavily soiled, the soil can crumble from other areas. Therefore, it is important to determine not only from which vehicle the earth was crumbled, but also from which parts of it. This allows you to more accurately indicate the location of the collision. In this case, the boundaries of the areas of crumbling of the smallest particles of earth and dust should be taken into account, since large particles can move further by inertia.
The location of the collision can be determined by the location of the scattering areas of the debris. At the moment of impact, fragments of glass and plastic parts are scattered in different directions. It is difficult to determine with sufficient accuracy the influence of all factors on the movement of debris; therefore, it is possible to indicate the impact site only by the location of the dispersion area (especially with its significant size).
When determining the collision site by the location of the debris in the longitudinal direction, it should be borne in mind that the debris in the direction of vehicle movement is scattered in the form of an ellipse, the nearest edge of which passes from the impact site at a distance close to the place of their movement in the longitudinal direction during the free fall. This distance can be determined by the formula:
where,
Vа - vehicle speed at the moment of glass breakage, km / h;
h is the height of the location of the lower part of the destroyed glass, m.
As a rule, the smallest fragments lie closest to the impact site; large fragments can move much further, moving along the road surface after falling by inertia.
By the location of small debris, the collision site is more accurately determined on a wet, muddy, dirt road or on a road with crushed stone, when slipping of small debris on the road surface is difficult.
In head-on collisions, the impact site in the longitudinal direction can but example but to determine, based on the location of the distant boundaries of the areas of scattering of glass fragments, rejected from each of the vehicles, colliding in the direction of its movement. With a similar nature of destruction of a glass of the same type, the maximum distance of discarding debris when they move along the road surface is directly proportional to the square of the vehicle speed at the moment of collision (Fig. 1). Therefore, the collision site will be located at such a distance from the far boundary of the scattering area of glass fragments of the first vehicle:
where S is the total distance between the far limits of the areas of dispersion of glass fragments of oncoming vehicles;
V1, V2 - vehicle speed at the moment of collision.
Figure 1. Determination of the collision site by the scattering range of glass fragments
When marking the distant boundaries of the areas of scattering of glass fragments, one should exclude the possibility of error, i.e. consider as discarded those debris that were carried out by the vehicle during its movement after the collision.
By the width of the road, the collision point can be indicated approximately in cases where the scattering area has a small width and the direction of the longitudinal axis of the scattering ellipse can be set. It should be borne in mind the possible error in cases where theThe impact of debris to the right and to the left of the vehicle's direction of movement was uneven (for example, due to the ricochet of debris from the surface of the second vehicle).
Determination of the place of collision by the final location of vehicles
The direction of movement and the distance the vehicle moves from the collision site depend on many circumstances - the speed and direction of the vehicle, their masses, the nature of the interaction of the contacting parts, resistance to movement, etc. Therefore, the analytical dependence of the coordinates of the place of collision of the vehicle on the values that determine these circumstances is very complex. Substitution in the calculation of the formula of quantities even with small errors can lead an expert to wrong conclusions. It is practically impossible to determine the values of these quantities with the required accuracy. It follows that, based on the data on the location of the vehicle after the accident, the place of collision can be indicated only in some cases.
Figure 2. Determination of the place of collision by the final location of the vehicle.
1 - vehicle at the moment of collision; 2 - TS after impact
When carrying out expert examinations on cases of about, the question is often raised on which side of the carriageway a collision of vehicles moving in parallel directions occurred. To solve this issue, it is necessary to accurately determine the lateral displacement of the vehicle from the collision site, which, in the absence of data on the tracks on the road, can be found out by the location of the vehicle after the accident.
The most accurate place of collision is determined in those cases when, after the impact, vehicles continue to contact (or diverge to a small distance). Lateral displacement of the vehicle from the place of collision then occurs due to their rotation around the center of gravity. The displacement values of the vehicle are approximately inversely proportional to the values of mass (or gravity), then to determine the lateral displacement from the collision site, you can use the following formula:
where,
Yk is the distance between the centers of gravity of the vehicle after the accident (final), measured in the transverse direction, m;
Yo- the distance between the centers of gravity of the vehicle at the time of the accident, measured in the transverse direction, m;
G1 andG2 - vehicle mass, kg.
Clarification of the place of collision by deformations of vehicles
Investigation of the damage sustained by a vehicle in a collision often makes it possible to determine the relative position at the moment of the collision and the direction of the impact. So, if the direction of movement and the location of one of the vehicles that collided at the moment of impact are determined, then the location of the second vehicle and the point at which their initial contact occurred is determined by the damage. In many cases, this makes it possible to determine on which side of the road the collision occurred.
If only the location of the vehicle after the accident is known, then from the damage it is possible to determine the direction of the impact and the likely displacement of the vehicle after the collision. The place of collision can be most accurately determined when the distances by which the vehicle has moved after the impact are insignificant.
In collisions resulting from a sudden left turn of one of the vehicles, it is possible to determine the extreme right position of this vehicle at the moment of impact, based on the possibility of performing a maneuver under certain adhesion conditions. In some cases, this makes it possible to find out on which side the collision occurred, if it is determined from the deformation at what angle the impact was struck.
Characteristics of vehicle damage
In the event of a collision of vehicles, the main task of the expert study is to determine the collision mechanism, as well as to determine the location of the collision site of the vehicle relative to the boundaries of the carriageway and centerline. When installing the collision mechanism, the damage on the cars is studied (during the transport and trace examination), and the main ones when determining the place of the collision are the traces recorded in the accident diagram. All traces subject to expert analysis can be conditionally divided into two groups - these are traces in the form of damage on vehicles, and traces left by the vehicle on other objects (carriageway, on road elements, etc.).
All traces in traceology are classified as:
Volumetric, having three dimensions (length, depth, width);
Surface, two-dimensional;
Visible to the naked eye;
Invisible;
Local:
Peripheral, located outside the zone of influence and formed by permanent deformation;
Point and Linear.
Positive and negative;
Layering and delamination.
In the transport traceology, the traces of a collision of a vehicle, the classification of which was given earlier, have 9 names adopted to describe damage during transport and traceability examinations:
1. Dent is damage of various shapes and sizes, characterized by the indentation of the trace-sensing surface and appears as a result of its permanent deformation;
2. Burrs are traces of sliding with raised pieces, parts of the trace-sensing surface formed when the solid surface of the particles of one vehicle comes into contact with the less rigid surface of another vehicle.
3. Breakdown - through damage more than 10 mm in size (used both when examining tires and to describe damage to vehicle parts).
4. Puncture - through damage up to 10 mm (used only when examining tires.
5. Scratch - a shallow, superficial damage, the length of which is greater than the width and without removing the surface layer of the material (despite the paintwork).
6. Layering - associated with the process of trace formation and the transfer of material from one object to another.
7. Detachment - the separation of particles, pieces of metal, and other substances from the surface of an object.
8. Scraping - the absence of pieces of the upper layer of trace-sensing material, caused by the action of the sharp-cutting edge of another object.
9. Pressing - pressing the victim by a vehicle against another object or between parts of the vehicle itself (used in the production of complex autotechnical and forensic medical examinations).
The most informative signs indicating the location of the collision site are the traces of the movement of vehicles before the collision. Such marks can be traces of braking, rolling, side shift, slipping, etc. At the same time, establishing the place of collision by traces of the movement of cars requires research both the nature of their location and their belonging to a particular car and even a wheel. So, if on the diagram, on the carriageway, a braking trace is displayed, which at first was directed straight ahead, and then sharply deviated to the side, then the place of the deviation of the tracks indicates that during the movement of the car it was affected by the shock load, which led to the deviation vehicle movement. Shock loading is the interaction of vehicles in a collision. Therefore, when determining the place of collision, both the place of change in the direction of the braking traces and the location of the place of primary contact in the car itself, which is established when determining the collision mechanism, are taken into account.
Side shift marks also indicate that their formation was caused by a collision of cars, and when establishing the belonging of certain tracks to specific wheels of the collision mechanism, the place of the collision is determined.
Trace information indicating the location of the collision site includes traces in the form of debris or dirt from the lower parts of the vehicle in a collision, as well as traces in the form of scratches, burrs, and potholes on the road left by deformed parts of the vehicle after the collision. In this case, when determining the place of the collision, it is necessary to first establish which part and which vehicle left these marks on the road. This is established by an expert review of damaged cars. This also takes into account the collision mechanism, that is, the ability to move the car that left a mark on the road from the immediate place of collision. Most often, there is an accident in the scheme, only a scree of glass fragments of small parts from cars, which, moreover, occupies both lanes. In accordance with the methodological recommendations, the scattering of glass fragments and other small parts of cars that separated during a collision indicate only the area in which the collision site was located, and not the place itself. Therefore, the determination of the coordinates of the place of collision by the location of the debris of glass fragments, as well as bulk cargo in this case, can be done by the method of excluding territories. The essence of this method is that the talus zone is first divided into two sections and, taking into account the study of the collision mechanism, the final position of the vehicle, as well as other traces of the vehicle's movement, they do not independently bear informative signs of the location of the collision site, one of the sections is excluded. Then the remaining area is again divided into two zones, etc.
When applying this method, it is advisable to use full-scale modeling in the place of an accident or plane modeling in a large-scale scheme.
When installing the collision mechanism of the vehicle, as noted, there is trace information in the form of damage on the vehicles themselves. At the same time, in transport traceology, there is no differentiation of objects into trace-forming and trace-perceiving, because any damage site is simultaneously both trace-forming and trace-perceiving. In expert practice, the establishment of a collision mechanism for damage on vehicles consists of next steps research: split research, comparative research and in-kind comparison of vehicles. Moreover, if the first two stages are mandatory, without which the installation of the collision mechanism is impossible, then the third stage cannot always be carried out, and the impossibility of its implementation does not depend on the expert. In this case, the expert should conduct a simulation based on the first two stages of the study. It is necessary to point out one more type of trace information studied by experts in the production of complex autotechnical and forensic medical examinations. These traces are marks on the victim's clothes, as well as traces in the form of bodily injuries on the victim's body. The study of such traces in conjunction with traces on the vehicle makes it possible to establish the mechanism of the car hitting a pedestrian.
The most difficult research should be considered research to determine the identity of the one who was driving at the time of the accident. In this case, traces on the road, traces on a vehicle, as well as traces on the bodies of people who were in the car at the time of the accident are examined.
Analyzing the above, it should be pointed out that the assessment of trace information in each specific case is individual and cannot be an established method once and for all, but requires an expert to abstract thinking, covering the entire gamut of traces, as well as to take into account the described evaluative features in the traces.
Application
Examples of the typical relative position of vehicles at the moment of collision (depending on the angle between the vectors of their speeds):
1. Longitudinal, opposite, straight, blocking, central, anterior.
2. Longitudinal, passing, straight, blocking, central, back.
3. Longitudinal, opposite, straight, tangent, eccentric, lateral.
4. Longitudinal, passing, parallel, tangent, eccentric, lateral.
5. Cross, transverse, perpendicular, blocking, central, left.
6. Crossover, passing, oblique, sliding, eccentric, left.
7. Crossover, oncoming, oblique, sliding, eccentric, left.
