Forensic investigation of traces of vehicles. Signs of the direction of movement of the vehicle Signs indicating the direction of movement of the car

The following traces, studied transport traceology:

1. running gear traces;
2. traces of protruding parts of the vehicle;
3. parts and details separated from the vehicle (traces-objects).

Study of any of the above groups may be accompanied by an analysis of trace substances, which will not be a traceological, but a material science study.

Traces of vehicles are important in the investigation of traffic accidents, as well as crimes in which the vehicle was used to take out the stolen goods, to arrive and leave the crime scene, etc.

The study of the above groups of traces allows solving both identification and diagnostic problems of transport traceology. So, according to the traces of the chassis, protruding parts, separated parts and parts, a vehicle can be identified (or its group affiliation can be established). At the same time, their study makes it possible to solve problems related to the mechanism of the event, i.e. determine:

- direction and mode of movement;
- place of collision (collision);
- angle and line of collision, etc.

Traces of running gear

Types of traces of the running gear of transport

Traces of the running gear are left by trackless transport (cars, motorcycles, bicycles, tractors, carts, sledges). In view of the greatest prevalence of automobiles, it is advisable to confine ourselves to studying the traces of their running gear. At the same time, many data will be similar for other vehicles (motorcycles, tractors).

There are the following types of traces of the running gear of vehicles:

1. rolling marks arise as a result of the translational-rotational movement of the wheel, braking and slipping;
2. slip marks occur when the wheels are completely blocked during braking.

Depending on the properties of the receiving surface running gear traces can be:

1) surface:

- traces of layering (the car drove through a puddle, and then on dry asphalt; positive - from painted protruding parts, and negative - from dirt particles stuck in the recesses between the wheel lugs);
- traces of delamination (traces on a contaminated surface).

2) voluminous(they are the result of residual deformation of the soil - sand, clay, loose earth, and are able to transmit not only a three-dimensional copy (model) of the running part of the tread, but also data on its side parts).

According to the traces of the chassis determine:

orientation and mode of movement (braking, stopping) - diagnostic task;
type, model of the car, and in the most favorable cases, its identification is carried out - identification task.

Differentiation of trucks and cars in their tracks is carried out taking into account the presence or absence of rear twin wheels, the size of the base of the car and the track width.

Track width- this is the distance between the center lines of the track of the left and rear wheels or between the gaps of the rear twin wheels. It should be noted that the prints of the rear wheels are displayed in the tracks of vehicles, which completely or partially overlap the tracks of the front wheels.

Vehicle base is the distance between the axles of the front and rear wheels. For semi-trailers, a common vehicle base (distance between the 1st and 3rd axles) and a bogie base (distance between the 2nd and 3rd axles) are distinguished.

The base of the car is measured in the wake of a stop (clear, deep tracks or thawed spots in the snow) or in the place where it turned around using reverse gear.

Having determined the type of vehicle, proceed to the establishment of the model. To do this, along with those listed earlier (base, track), such features as the width of the running part of the tread, the tread pattern, and the outer diameter of the wheel are used.

The width of the running part of the tread is measured in a section with a clear display of the pattern, from one edge to the other. The tread pattern (shape, mutual arrangement and dimensions of the lugs), displayed in the track, is photographed, all elements of the pattern are measured and recorded in the protocol. Then, with the help of a specialist, it is determined which car (which model, group of models) corresponds to a given track width and a tread model with a given pattern.

The information obtained from the cumulative assessment of the above features serves the purpose of searching for a vehicle.

Forensic investigation of traces of the running gear of vehicles

When a vehicle is detected, it can also be identified by displaying signs of tread defects.

For solutionsdiagnostictasks(determining the direction and mode of movement (the fact of braking, stopping, etc.), you can use the following features displayed in the traces:

- the tread pattern, which has herringbone-type elements, must face the open part in the direction of movement;
- when the vehicle moves along loose soil, soil particles are located on both sides of the wheel track in the form of a fan, the diverging ends of which are directed in the direction opposite to the movement;
- on an asphalt road, when crossing puddles, areas of scattered dry soil in the direction of travel, there is a trace of moisture (dust) that disappears;
- drops of liquid (oil, brake fluid, water) falling during movement are pear-shaped, with their narrow end facing the direction of movement;
- when moving rods, chips, branches, the ends of the latter are turned in the direction of movement;
- when moving on the grass, its stems will be crushed in the direction of movement (in the absence of towing);
- a stone pressed into the ground as a result of the move will have a gap in the track from the side opposite to the direction of movement;
- on the turning section, the angle of divergence of the wheels increases;
- the stepped relief in the traces of the sloping part of the steps faces the direction of movement.

Braking is judged by the decreasing clarity of the tread pattern, by the change in pattern, and by the presence of transverse stripes. If during full braking there are traces of "skid" (slip), then they are used to determine the speed of the car before it stops (autotechnical examination). To do this, measure the length of the traces of the rear wheels or the total length of the braking trace, from which the value of the vehicle base is subtracted.

All the above signs of traces of the running gear are reflected in the inspection report.

Tracked vehicle

If found at the scene tracked vehicle tracks, then measure and fix:

1. track width (distance between the midpoints of track tracks);
2. width of track tracks (tracks);
3. configuration and dimensions of traces of links (tracks, shoes);
4. the number, shape and size of traces of the grouser of the link (track).

horse-drawn transport

If the traces are left by the wheels of horse-drawn vehicles (wagons, carts, carts), then the measurements are carried out the same as for the traces of the car. However, when evaluating the results obtained, it is taken into account that the measured track width may be slightly larger than the true one due to the movement of the wheel on the axle.

Along with this, traces of hooves (horseshoes, paws) of animals used for movement are also recorded. The display of hooves (horseshoes, paws) allows you to judge the type of animal (horse, camel), signs of gait (track tracks), direction and type of movement (step, trot, gallop), general and particular signs of hooves or horseshoes. Under favorable circumstances, animal identification is carried out on these grounds.

Traces of the undercarriage of the vehicle are fixed in the same way as the traces of a person's feet. A trail of considerable length is photographed using the linear panorama method. Sections with the most pronounced tread pattern are removed separately. All photographs are taken using a scale bar. A plaster cast is made from the clearest part of the tread, where individualizing features are displayed. The size of the cast should not exceed 40x40 cm, otherwise it may break. Therefore, the track area is fenced off.

If traces of the running gear are found on the clothes of the victim (collision, crossing), then they are photographed several times. First you need to capture the entire piece of clothing so that you can see the location of the tracks. Then - the trace itself, after straightening the clothes from the folds and placing a scale ruler next to it.

Casts and photographs of traces of the undercarriage seized at the scene of the incident are sent for expert examination.

The following questions may be asked for permission of the trace examination::

- which model tire left a trace;
- type (make, model) of the vehicle that left traces at the scene;
- in what direction was the vehicle moving that left traces;
- whether the trace is formed by this tire;
- what wheels (front, rear, right, left) left marks on the clothes of the victim.

If the task of the trace examination is to identify the running gear of a particular (known) car by traces, then the main attention should be paid to the preparation of materials necessary for a comparative study: a wheel (tire) or their prints (track samples). The best option is to present the wheel as an assembly, but this is not always possible. It is not recommended to send a vehicle for examination under its own power, since private identification signs may be destroyed during the run. Therefore, the most common option is to submit the pneumatic tires themselves or samples for examination.

Samples are obtained taking into account the nature of the traces to be investigated: bulk or surface. To obtain volumetric traces, the car is rolled at low speed on the ground, capable of displaying general and particular signs of the tire (for example, wet sand). In this case, a trace is obtained with a length of 2-3 turns of the wheel. The resulting traces are carefully examined and two sections are selected containing the display of signs similar to those observed in the casts taken from the scene. Plaster casts are made from these areas.

If the traces are superficial, then the experimental samples are also superficial. To do this, a dye is applied to a section of the tire with signs similar to those recorded at the scene of the incident (printing ink is rolled out on a flat surface and applied to the section of the tire with a colored rubber roller) and this section is copied.

If, during the inspection, a matching section could not be established, then prints (traces) of the entire wheel are obtained. To do this, a layer of paint is applied with a brush or spray gun on a sheet of plywood or on smooth dry asphalt. The vehicle drives slowly over a painted surface and then over long strips of thick paper (such as the back of wallpaper). And in this case, it is desirable to obtain prints of two or three revolutions of the wheel.

Separated from the vehicle parts and details (traces-objects)

Separated parts and parts found at the scene are used to search for the vehicle, identify it, as well as to determine the area of collision, collision.

The objects remaining at the scene of the incident can be grouped as follows:

- fragments of headlight glass, organic glass and other glass components of the vehicle;
- pieces (particles) of paintwork;
- fragments of parts of the vehicle;
- components or fasteners of individual assemblies.

The study of headlight and other fragments allows you to establish the type, model, brand of the product and, depending on this, the model of the car. These data, together with others, are used to search for him. If homogeneous fragments are found in the checked vehicle, then an examination is carried out to establish the whole in part.

Particles of the paintwork allow you to set its color and include this data in the wanted information. After the vehicle is found:

trace examination(establishing the coincidence of the pieces along the separation lines and determining the place where the paint used to be);
materials science expertise(comparison of the chemical and physical properties of the paintwork).

As fragments of parts of vehicles found at the scene, those parts that are mounted outside the car most often appear: side (outside) rear-view mirrors, antenna, additional side headlight, door handle (protruding), bumper fang, bumper and other parts . If they are found, the shape, design, purpose of the part determines its type and, depending on this, the model (brand) of the car. After establishing the vehicle, it is identified by the separated part. To do this, they make up (at the site of the breakdown) a part found on the spot and a part preserved on the car.

Traces of protruding parts of the vehicle

Traces of protruding parts of the vehicle are traces of contact interaction (traces-mappings). They are formed:

- in the event of a collision between two or more vehicles;
- when hitting the body (clothing) of the victim (collision);
- when moving through the human body;
- when the vehicle comes into contact with environmental objects (poles, trees, walls, fences, etc.).

Traces of contact interaction are studied:

1. to identify a vehicle that fled the scene;
2. for the reconstruction of the event of a road traffic or other accident, i.e. determining which parts and in what sequence these traces were left.

Speaking of such traces, traces are also distinguished:

- static;
- dynamic.

static traces

The first are formed when the impact force is extinguished at the moment of contact. Volumetric static traces display the external structure of the trace-forming object (details, car parts) in its three dimensions. The dents that arise in this case on the wings, body, doors repeat the shape of the parts that left them: bumpers, headlights, hooks, handles, etc. With a very significant impact, the part leaves a hole. According to it, one can only approximately judge the size, the contours of the detail that left it.

Static surface traces are not associated with a change in the shape and integrity of the perceiving surface. They display the external structure of the part that left them in two dimensions - length and width. Surface marks are formed due to layering (dirt, paint, lubricants) or delamination (transfer, removal, copying of particles with a receptive surface).

Dynamic traces

Dynamic traces arise in the process of the incessant movement of at least one of the vehicles. In this case, the impact force is directed at a certain angle and is greater than the friction force. Dynamic traces look like dents, cuts, scratches, scrapings, scuffs, layers.

To identify and analyze traces, the car is inspected in a certain sequence: first, the front surface (radiator lining, hood, headlights, bumper, windshield, etc.), then the left side (doors, body, glass, tires), rear (body , trunk, license plate, lights, etc.), the right side surface, after which - the roof and, finally, the lower part facing the road surface. Particular attention is paid to those surfaces that participated in the formation of contact marks; so, when hitting a pedestrian, these will most often be: radiator lining, fenders, headlights; when moving a person - protruding parts of the front and rear axles, oil pan, gearboxes, cardan shaft, etc.

When analyzing traces of vehicle collisions, it is assumed that collisions can be:

- counter;
- passing;
- angular (movement at an angle to each other).

A variation of the first two is a sliding side collision. At the same time, vehicles practically do not change direction (if the difference in their masses is insignificant). A kind of corner collision is a cross collision, i.e. at a right angle (the longitudinal axes of the colliding vehicles are perpendicular).

Traces are located depending on the type of collision. By studying them, first of all, the traces of primary and subsequent contacts are differentiated - impact, overturning, etc.

Traces of primary contact arise from the introduction of one vehicle into another. It is characterized by many dents, displacement of the metal in a certain direction. The areas of primary contact are determined by the location of the greatest deformation of the metal.

Of great importance in the analysis of traces of a collision is the selection of a counter-pair of traces - sections that interacted with each other. The selection of such pairs is based on the study of their shape, size and height from the road surface.

Such an analysis allows, already during the inspection at the scene, to get an idea of what traces on one vehicle were left by specific parts of another. The shape of the dent determines which part (part) left it and in which direction the object that left the dent moved. When examining scratches, pay attention to their direction. At the end of the scratch, peeling of the primer is observed, which has a drop-like shape, with its wide end directed towards the action of the force that caused the peeling. The cracks running along the sides of the peeling of the primer are directed towards the application of the force. Foreign inclusions embedded in the scratch (rubber, glass, paint, etc.) help to identify the area (detail) that left the mark.

A scratch running parallel to the vehicle's axle indicates a side (gliding) impact. If it is directed downwards, then the other car has sharply slowed down and sank; if the scratch is pointing upwards, this indicates a sharp decrease in the speed (braking) of the car on which the scratch remains.

When studying the cut, it is determined by which sharp part (detail) it could be left, in which direction this part (and, consequently, the vehicle) moved, whether there are paints, primers, other particles on the edges of the cut from the part that made the cut.

Traces from the protruding parts of the vehicle are recorded in detail in the protocol, noting their location, type, size, shape, height from the road surface. The traces are photographed both together with the object on which they are found, and separately (with a scale bar). A schematic sketch of the shape, location, size of traces is possible.

1. Types of traces of vehicles and their forensic significance.

2. The work of the investigator with traces of vehicles.

In the practice of investigating crimes, traces of cars, motorcycles, tractors, horse-drawn carts, and sledges are often used. Under vehicle tracks means traces of the contact impact of running and non-running parts of vehicles, traces on objects that have separated from the vehicle, as well as various material-fixed changes on the road associated with traffic.

At the scene of an accident, vehicles, depending on the situation, may leave traces representing all types of forensic classification.

traces-displays(traces of the chassis) are formed in the form of traces of rolling or traces of slipping of the wheels that occur in a braked state (skid), prints (volumetric and surface) of the tread pattern, caterpillar tracks on the road surface, on the clothes and body of the victim, and also in the form of dents , chips, scratches, potholes - on obstacles, trees, buildings. Traces in the form of potholes, furrows or scratches remain on the road surface from parts of the body, chassis or transmission of a car that collapsed as a result of an impact during an accident. The same traces are left by the details (steering wheel, footboard, pedal) of an overturned motorcycle. Investigative practice knows cases of displaying protruding parts of a car on a trace-perceiving object, an imprint of its state sign in the ground or in a snowdrift.

Traces-objects remain at the scene of a traffic accident in the form of car parts - wheels, headlight rims, fragments of a windshield and headlight glass, chips from the body, elements of the victim's clothing, part of the cargo transported in the back of a vehicle.

trace substances at the scene, for example, of a traffic accident, they are puddles and splashes of fuels 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, accumulations of particles of dirt, dust, earth, showered from the lower parts of the car in a collision with an obstacle.

Depending on the nature of the road surface traces of vehicles are divided into volumetric (depressed) and surface. Volumetric traces are depressions that vehicles leave when driving on a soft surface - earth, clay, snow, sand. surface marks formed on paved roads (concrete, asphalt), on flat objects lying on the road, on the clothes of the victim.

Surface marks, in turn, are subdivided into traces of layering and traces of delamination. Traces of layering are formed when a trace-forming substance is transferred from the wheel to the road. Such traces are formed when a vehicle leaves roadsides, country roads onto a paved road. Traces of delamination are formed when a trace-forming substance is transferred from the road surface to the wheel. Similar marks remain after the tire of the wheel comes into contact with the spilled coloring matter on the road.

According to visibility vehicle tracks are divided into visible, invisible and invisible. So, the trace of blocked 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 forensic tools and logical techniques for modeling the event of a traffic accident.

Depending on the location of the changes on the trace-perceiving object, traces can be divided into local and peripheral. local footprint arises as a result of changes in the trace-perceiving object within its contact with the trace-forming object. The wheel tire leaves a track, changing the ground within the pressure on it, and the rest of the ground surface remains in the same state. peripheral footprint is formed by changes that occur outside the contact of the wheel and the road. So, outside the contact, some substance can be layered or, conversely, part of the substance can peel off.

Depending on the trace formation mechanism 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 the trace-forming surface in an unfolded form. dynamic footprint formed as a result of braking, skidding, wheel slip. Brake marks differ from static rolling marks in that they are stretched, the elements of the tread pattern are lubricated, which is caused by a slowdown in the speed of rotation of the wheel during braking and, thereby, a discrepancy between its speed 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 lock), thus, the braking marks turn into slip marks (“skid”), that is, continuous smeared tracks, where individual elements are no longer distinguishable.

According to the characteristics 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 track It is formed under such circumstances when the conditions of trace formation turned out to be unfavorable for the preservation of other traces of the vehicle (other wheels). A motorcycle that does not have a side trailer leaves only a single track when moving quickly on a flat road surface. track track It is formed under conditions equally favorable for the following objects (wheels) located on both sides of the vehicle. The rut track includes individual tracks, and therefore everything that applies to working with a single track, fully applies to the tracks that form the rut. In the track itself, there are traces of rectilinear movement, traces of a turn, traces of a turn with maneuvering, and traces of a stop.

Traces of drawing. When hitting a person or an object, the vehicle can drag it along for some distance. In this case, there may be dynamic drag marks in the form of smeared strips. The length of the traces of dragging depends on the features of the dragged object, on the speed of the vehicle, on the condition of the road. On a road covered with asphalt, drag marks 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 traffic accident, the place where the collision occurred, as well as the subjective reaction of the driver who continues to move.

Traces of caterpillar vehicles are formed by tracks that make up the caterpillar. They remain in the form of two strips, the distance between the centers of which corresponds to the track width. Traces of tracks allow you to determine the type and model of a combat or special vehicle. These traces display general (number of tracks on a track, distance between tracks, nature of track relief) and particular (deformation of track edges, differences in distances between individual tracks) signs of a track, by which it is possible to identify the vehicle.

Skid tracks remain during the movement of horse-drawn sledges, snowmobiles or skis. The tracks of the runners belong to the sliding tracks formed by the plane, their dynamic nature 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, skid width, guide chute width. As private signs, sometimes relief irregularities located at the ends of the runners can be displayed.

Along with the traces of vehicles, forensic significance are traces of horse-drawn wheeled vehicles. In practice, carts, carts, carts are still used. Some of them are equipped with rubber tires, the tracks of which are not much different from the tracks of vehicle tires. Most of the horse-drawn carts have wooden wheels with metal rims, on the tracks of which it is possible to establish a group affiliation, and with a sufficient combination 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 proof a number of important circumstances of a criminal event (traffic crime, crimes against a person, against someone else's property - in cases where transport is used). In particular, it is possible to find out the mechanism of a traffic crime or an accident, both as a whole and its individual elements.

So, according to the length of the brake track, the speed of the car before the start of braking, its braking and full stopping distance are determined. According to the trace left on the road surface by a car tire (tread pattern, width of the running track), it is possible to establish its model.

According to a number of signs, it is possible to identify the vehicle in its tracks. These include signs due to a defect in the tread, signs associated with the production of tires. With the use of anti-skid means (studs, chains, tracks), as well as random signs (foreign objects stuck in the tread grooves or embedded in rubber).

The technical condition of some vehicle units may be evidenced by traces of engine oil, brake fluid, etc. left at the scene (for example, at a parking lot).

According to the track width and the size of the base of the car, its type and brand are determined. 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 during a collision or collision at the scene.

The clarification of these issues that determine the forensic significance of traces of vehicles is carried out by the investigator during the inspection of the scene, when performing other investigative and other actions. So, when preparing for the interrogation of a suspect, the investigator can independently determine the approximate speed of the vehicle immediately before its braking. This is an element of a preliminary (pre-expert) study of the circumstances of the event and is aimed at creating a tactical advantage over the suspect already at the initial stage of the investigation, in particular, at his very first interrogation.

The main part of the questions is subject to clarification by specialists within the framework of transport-trasological, autotechnical and other examinations, the preparation of materials for which is entrusted to the investigator.

Fixation, fastening the results of the inspection are carried out by describing in the protocol, making diagrams or plans, photographing, video filming, as well as by making casts and copies of tire tracks.

First of all, even before the start of the inspection of the scene and during it, it must be carried out photography. Photographs may be taken depending on the nature of the incident and the circumstances of the case. section of the road where the accident occurred, general view of the center of the scene (car, corpse), wheel tracks, cargo. For these purposes, various methods of photography are used.

With the help of orienting and overview photography, a general view of the scene of the incident and its surroundings are photographed. This survey is usually made from two opposite or more sides.

The following elements shall be recorded in the report of the inspection of the accident site and its annexes:

1) road; sections of the scene and objects on which traces of vehicles were found, with an accurate description of their location and features;

2) vehicle;

3) traces of the vehicle;

4) signs indicating the direction of movement of the car (if necessary);

1. When describing road section where the accident occurred, the report of the inspection of the scene of the accident indicates the relief of the road, transverse and longitudinal slopes, the condition of roadsides, ditches, roadbeds, turns and curves (if necessary), and traces of lubricants and liquids used for vehicles are recorded , vehicle parts found at the site of the incident, prints of numbers and units of the vehicle on various objects.

2. Description in the protocol vehicle(car, truck, tank, armored personnel carrier) involves the reflection of the following elements in it:

- the position of the vehicle relative to the carriageway, fixed landmarks, other means involved in the incident, the corpse;

- brand, model of the car, year of manufacture, state number, body and cabin color, tire model, pattern type, residual tread depth;

- 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 the light switch keys, position of the gear levers, engagement of the front axle, main clutch (for tracked vehicles ), the condition of the windshield, rear-view mirrors, triplex;

- damages on the vehicle, their nature and localization;

- the presence and localization of foreign traces-overlays and their characteristics (peeling off 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 described in the protocol of the inspection of the scene tire tracks vehicle must be:

– type and condition of the road surface;

- the location of the traces relative to fixed landmarks;

– type and number of traces;

- the width of each treadmill;

– depth of volume traces;

- track size;

- the structure of the tread pattern, the nature of the prints of the features of the surface of the tire;

- vehicle base

- the length of the braking track;

- signs of the direction of movement;

- a method of fixing, removing and packing a 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 mark on the road surface are washed away by rain or weathered over time, as a result of which the length of the braking track decreases. So, in 1-2 hours, the braking trail on an asphalt concrete pavement can become shorter by 0.2-0.3 m.

Treadmill Width measured along the perpendicular to its longitudinal axis and along the bottom of the track, if it is voluminous. There may be slight differences (10-15 mm) between the width of the tread and the width of the tire tread, depending on the tire pressure and vehicle load.

Track– These are the marks left on the road by the tires of the right and left wheels. Measurements are made between the centers of the traces, the results of which are to be included in the inspection protocol.

4. When a vehicle moves on the road, various material-fixed changes occur, by which it is possible to judge the direction of traffic, the direction of movement is determined by signs in the wheel tracks and other signs on the road.

Signs of the direction of movement and parking place of the car:

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 driving through puddles, mud marks will loosen and disappear as you move, and splashes of water and mud will fan out in the direction of travel.

3. Drops of liquid falling from the vehicle have an elongated shape (round with a narrowing), the sharp end of which is directed towards the movement.

4. When moving on tall grass, its stems lean in the direction of movement, and when moving on low grass, when slipping, the stems lean in the direction opposite to movement.

5. When moving a branch, a stick breaks, forming an angle open in the direction of movement.

6. When moving on the ground, the stone moves in the direction of movement, and the recess from the stone remains in the direction opposite to the movement.

7. When braking and skidding on soft ground, the soil shifts in the direction of movement.

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 angle of divergence of the front and rear wheels at the beginning of the turn is greater than the angle of convergence at the end of the turn.

10. When braking, the trail of skid sharply increases in the direction of travel and abruptly ends.

11. Tears on the clothes of the victim from the protector are directed in the opposite direction to the movement.

12. The parking place of the car, among other signs, can be determined by traces of fuels and lubricants, water, brake and coolant.

5. If a traffic accident is fatal, an inspection should be carried out corpse with the participation of a forensic medical expert. When examining a corpse, the localization of various injuries on the body of the corpse is recorded in the protocol for examining the scene of the incident and their shape is described. In addition, the clothes of the corpse, its condition and the traces on it (for example, traces of the surfaces of various parts of the vehicle - buffer, wing, wheel protectors, etc.) are carefully examined.

Recording the progress and results of the inspection of the scene of a traffic accident is also carried out by charting, which is an appendix to the inspection report, but at the same time, allows you to more clearly present the situation of the incident.

The progress and results of the inspection of the accident site are recommended to be recorded using video filming followed by video production. 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 scene of a traffic accident is a large area, as well as to record any events associated with an accident (for example, extinguishing a car on fire, lifting an overturned car).

The main technique for fixing and removing traces-images of vehicles is modeling by making casts. For this, generally accepted means of modeling volumetric traces are used, for example, gypsum, silicone paste "K", paste "U-1".

If there are voluminous traces , in which the features of the trace-forming object are displayed, plaster casts are taken from them.

Fixing traces on loose soil, in sand is produced with the help of binders. In practice, synthetic resins are widely used for this purpose, which are mixed with rapidly volatile solvents and applied to the track by spraying, due to which the latter, having obtained sufficient strength, can be removed from the ground without damage. Such compositions include a 6% solution of perchlorovinyl resin dissolved in acetone. An effective means of fixing traces in bulk solids is hairspray in aerosol cans. After varnishing and complete drying, the trace can be removed after 20-40 minutes. Such a trace remains in its natural form for a long time, which has a significant advantage over casts that fix the trace in a mirror manner.

surface marks transport are fixed by transferring them to a sticky substrate, for example, to large-format sheets of glossy photographic paper, which is moistened and the emulsion surface is superimposed on the trace and pressed tightly against it. Then the photographic paper is separated from the trace and placed with the emulsion up to dry. If black paper is needed to copy the trace, then the photographic paper is exposed, developed, fixed and washed. Also, surface marks are transferred to sanded rubber sheets 3-4 mm thick.

overlay traces, arising on the vehicle or left by the vehicle on other objects as a result of the incident, are seized, if possible, together with the tracker or separated from the object and packaged in accordance with the rules for the removal of microparticles.

Traces-objects with traces of the vehicle displayed on them, as well as objects that have separated from the vehicle, are withdrawn from the scene as a whole, listed in the protocol and attached to the case as material evidence.

Available at the scene traces of fuels and lubricants their samples are taken and placed in sealed glass vessels.

Speaking of 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 studies its pattern, trying to determine from it the brand of the car that left this mark. This is already a 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 a preliminary (pre-expert) determination vehicle speed immediately before applying the brakes, which in turn will allow him to investigate the crime more substantively.

First, the approximate speed of the car before braking on a road without a longitudinal slope can be determined by the following formula:

V- vehicle speed,

f- coefficient of adhesion of tires to the road (usually 0.6 is taken in calculations),

St- the length of the braking distance,

254 is a conventional mathematical unit.

Secondly, an idea of the speed of the car before braking with approximate accuracy can also be obtained using reference data.

There are different concepts in criminalistics. stopping distance of a car and full stopover.

Under braking way refers to the distance that the car travels from the moment you press the brake pedal to a complete stop.

Full stopover - the distance traveled by the vehicle from the moment the driver begins to react to the danger until it comes to a complete stop. The stopping distance is determined by the formula:

t1 – driver reaction time to danger- the interval from the moment the danger signal appears to the start of the impact on the brake pedal of the car. This time depends on the qualification, experience, age, health of the driver and other factors.

t2 – brake actuation delay time. During this time, the pressure from the main brake cylinder (or valve) is transferred to the wheel cylinders (brake chambers) and the gap in the brake drive parts is sampled. After the time t 1 + t 2 has elapsed, the brakes are applied and the vehicle speed begins 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- coefficient of vehicle operation (deterioration of vehicle systems, quality of adjustment, etc.). Accepted for trucks 1.4, for cars - 1.0.

V- vehicle speed.

f- tire grip coefficient.

Traces at the scene of an accident can be divided into the following:

vehicle wheel marks
traces (point and line) of vehicle parts on obstacles with which they interacted during an accident
traces of parts separated from the vehicle, as well as various substances (bulk cargo, oil, etc.)
traces of victims
marks on the vehicle

Traces at the scene of an accident, left from the wheels of the car, can be traces of rolling, braking, skidding. Such traces indicate the trajectory and direction of movement of the vehicle during an accident.

Roll marks

On snow, wet sand, clay, etc. these marks are three-dimensional imprints of the tread pattern.

imprint is the mark left by the tire tread on soft surfaces when the vehicle's wheels are spinning freely. Tread prints are clearly visible along and across the track.

On the asphalt surface, there are prints of the tread pattern 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 particular wheel of the vehicle (individual identification).

Traces of braking (sliding)

On asphalt dry pavements, this is a strip lubricated in the direction of travel, and on unpaved pavements, it is a loosened furrow.

slip marks(yuza) are the stripes left on the road by tires of braked (non-rotating) wheels. If the tire slides in the plane of the wheel, then its track is easy to distinguish from the print, 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's contact area with the road. In this case, no features of the tread pattern are visible.

Influence of car mass redistribution on skid marks. The redistribution of mass along the axles during vehicle braking often makes it possible to determine which wheels left a slip track - front or rear.

If the tire pressure is as recommended by the manufacturers, then during normal driving the vertical load in the contact area of the tread with the road surface is evenly distributed. When braking heavily, increasing the load on the front wheels has the same effect as lower tire pressure, and reducing the load on the rear wheels is tantamount to the effect of increased pressure. Front wheel slip marks from overloaded tires 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 somewhat blurred edges.

Rear wheel skid marks. In cases where there are skid marks on the rear wheels only, you must first find out if this is due to the use of one hand brake (which often leads to skidding). If this is the case, then the motives of the driver's action should be clarified: either the main braking system is faulty, or the driver's foot slipped off the pedal and using the handbrake was a natural reaction to this. Therefore, depending on the circumstances, it may be necessary to experimentally determine the grip force developed in road conditions by a single hand brake. 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 blocking the rear wheels decreased. To confirm that the brakes on the front wheels are working properly, check the vehicle.

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 drive of the rear wheel brakes. However, these devices are not always reliable, especially on low friction roads.

slip marks

The origin of tire slip marks may vary, but in all cases they are the result of simultaneous sliding and rotation of the wheels. The following is a description of the different types of slip marks left at the scene of an accident.

Slip marks from a running tire are very similar to front wheel slip marks. 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 the unevenness of its trajectory often indicates controlled vehicle movement.

Corner slip marks are left when the wheels are free to spin, but the tires slip sideways due to centrifugal force. The redistribution of the load on the outer two wheels in relation to the center of rotation usually results in slip marks from only these wheels, although on a very slippery surface, as a rule, this occurs from all wheels.

The tracks of the rear wheels of a vehicle of conventional design during normal turning are always inside the tracks of the front wheels, however, this rule is often violated when skidding. Often the slip track is just a narrow strip that is similar to one side of the front tire's slip track. Such a trace occurs due to the fact that the tire, deforming, rolls in a lateral direction under the action of centrifugal force.

Deceleration slip marks occur during heavy braking on a non-slip wheel surface without blocking and before blocking. They always precede the skid marks and are best seen in the direction of movement of small scratches from pebbles and grains of sand. It is usually not possible to determine where the slip trace ends and the slip trace begins. Both are included in the measured total braking footprint.

Acceleration slip marks occur when there is too much traction on the drive wheels. It is possible to distinguish them from traces of deceleration only with a very careful examination. When accelerating, pebbles and grains of sand break out of the tire from the pavement and, leaving scratches, are thrown back, while when decelerating, scratches appear as a result of particles being pressed into the road surface and their subsequent movement.

Collision slip marks show the exact location of the collision and appear as stripes or streaks across the vehicle's line of travel. Traces of sliding of blocked wheels under the impact of an accident noticeably change direction from the original. A free-rolling wheel, when hit, may momentarily lock up and leave a short skid mark on the road, which can be detected upon close inspection,

Measurement and fixation of slip and slip marks. The necessary data for a reliable estimation of the speed of vehicles involved in an accident is obtained as a result of the inspection and measurement of tire marks on the road. The result of the investigation largely depends on the thoroughness of these operations.

Determination of belonging of traces to a specific vehicle. It is very important to establish which particular vehicle the traces belong to. Often the driver admits that the traces were left by his car, or witnesses confirm this. Sometimes the confirmation of a witness about the creaking of slipping tires that took place is enough to identify the tracks. If there are no witnesses to the accident, signs of tire slip can be detected upon careful examination, however, when the vehicles are removed from the accident site, 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 an accident, then the track dimensions of the vehicle help to establish the ownership of the traces.

Start and end of the track. The point where the tire began to slip is easier to determine if the track is viewed along the track from some 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, switching places with the assistant.

Breaks in the slip track. Breaks in the slip track can be caused, firstly, by the separation of the wheel from the road surface. In this case, the breaks are very short and numerous. This is caused by a low axle load, which causes the wheels to bounce on bumps in the road. Before and after each break, the braking effect of the wheel is very large, which compensates for its loss during the absence of contact between the tire and the road. Therefore, the strokes of the trace and the gaps between them are measured together, although the length and location of each stroke should be specified. Calculations use full length. Secondly; Breaks in tire tracks can be caused by intermittent depressing of the brake pedal. They are usually longer than the breaks caused by the wheels coming off the road. The distances between the visible parts are quite large, since the driver in an extreme situation is not able to stop and resume braking so often that the intermittent trail that has arisen can resemble the image created by the periodic separation of the rear wheels. In this case, each segment of the track of a given wheel must be measured separately, and the actual sum of these segments should be used in the calculations.

Rectilinear sliding. Rectilinear is such 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 perform the calculations, it is necessary to measure the longest track left by one of the wheels, since it is obvious that they are all braked as long as at least one of them slides along the road. Indeed, if the wheel is not yet blocked, and the other has already begun to slip, the braking force on it will be the same or even greater than on the blocked one.

Such braking is typical not only for motorcycles, since the brakes on their wheels are independently driven, but also for other vehicles.

Skid sliding. Skid marks are curved skid marks, on the surface of which there are tracks located at an angle to the track boundaries, left by the protrusions of the tread pattern.

Brake and skid marks generally do not show wheel identification.

A sign of slipping with skidding is considered to be the exit of traces of the rear wheels beyond the limits of the track of the front wheels of the vehicle. In this case, the vehicle, along with moving forward, shifts sideways or rotates around a vertical axis.

In the presence of skid marks, 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 certain 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 large. This averaging method should only be used when rear and front wheel loads are approximately the same, which is the case for cars and light trucks, but not for semi-trailer tractors and dual rear wheel trucks. In some cases, to calculate the speed, it is enough to fix the part of the track where the straight-line slip occurred, without taking into account the place where the side slip or rotation of the vehicle began. The nature of the pattern that appears on the road depends on the ratio of the speed of rotation and the rectilinear advance of the vehicle. This means that no two traces can be exactly the same.

Changing the grip properties of the road surface along the track

Often the trail left by the vehicle passes through sections of road with varying quality of coverage, especially when braking starts at the intersection and ends behind it. In such cases, it is important to measure the track length within each section, i.e. from the beginning of the boundary between sections with different coverages and from this boundary to the end of the track. This is necessary in order to separately calculate the lost speed of the vehicle during the initial and final braking phases and thus accurately determine the speed before braking.

Motorcycle tracks

The interpretation of the traces of a motorcycle is associated with certain difficulties due to the fact that each of its wheels is braked independently of the other. An experienced rider always applies intermittent front wheel braking before applying the foot brake. In this case, the tracks of the motorcycle are examined in the same way as the brake 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 manifests itself in a lengthening of the braking distance, from which it is difficult to determine the actual loss of speed.

It can only be assessed during control braking with one rear brake on a motorcycle of the same brand, and the weight of the driver must be equal to that involved in the accident. It is important that this experiment be 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 process of an accident, leaves surface and depressed (point and linear - dynamic) traces on them. The study of these traces allows solving identification and a number of diagnostic problems, which makes it possible to clarify the place of contact of the object with the vehicle and the direction of its movement after such an interaction.

This kind of traces can be grouped as follows:

scratches, layers, lines, abrasions on the carriageway, formed by damaged parts of the vehicle (rods, levers, engine crankcase protection, etc.)
road damage in a collision. The traces that occur during a collision are usually short, but sometimes deep due to the enormous forces developed during the collision. Sometimes parts of the vehicle break off on impact and dig into the road surface. An example of this is the cardan mechanism, which is often destroyed in an oncoming collision. These potholes can often be used to identify a particular vehicle, and sometimes they provide the only way to determine the exact location of a vehicle at the time of impact.
scratches, tracks left by the wheel disk of the vehicle when the tire is damaged and it moves on a tire with insufficient pressure
scratches, layers of paintwork (LKP), formed when the vehicle rolls over

Scratches as tracks are very important for determining the position of the vehicle during a collision and especially its movement after a collision. Similar traces may also appear when vehicles are removed from the accident site. They can be excluded from consideration by interviewing, if necessary, the persons who manage the emergency evacuated equipment after the emergency.

Damage showing the path of a vehicle after a collision often takes the form of long, thin scratches drawn by damaged parts of the vehicle that have touched the road surface (e.g. suspension parts, after a wheel has come off, body angle, etc.) Sometimes the damage can be in the form abrasions, short, flat or wide scratches that appear due to the large area of \u200b\u200bcontact of the car with the road, for example, when its roof slides.

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 the vehicle, but also the relative position of the vehicles.

Important for the investigation of an accident are traces in the form of particles separated from the vehicle and macro particles of paintwork:

talus of small particles
talus of soil or soil upon impact at the time of collision or collision. The location of the smallest particles or dust, combined with other features, 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 (their location may change under the influence of wind)
fragments of glasses of headlights, sidelights, rear-view lamps. According to the areas of their dispersion, it is possible to approximately establish the trajectory of the vehicle after contact and determine the place of its stop (in the absence of a vehicle at the scene of the incident)
exhaust traces. Using them, it is possible to establish the place where the vehicle stops, including relative to the boundaries of the carriageway

Traces left by the victims:

rubber shoe marks are noticeable on the concrete roadway, some are well detected on snow and soft soils. Such traces, due to the fact that they can be located at some distance from the place where other traces of the collision were found, are extremely rarely recorded. Footprints quite accurately indicate the place of collision and the direction of the applied force.
traces of dragging the body of the victim. On the paved surface, these are traces of blood, and mixed with asphalt dust or dirt, they look like stripes - peeling dust (dirt)
discarded personal belongings that the victim had (bag, food, etc.). They can be located both directly at the place of collision, and at some distance from it along the inertial movement of the vehicle.

Traces that appear on the clothes and shoes of the victims

Traces of contact of the vehicle with the clothes and shoes of a pedestrian when hitting or moving

imprints (point traces) of the headlight rims, lining, decorative and other details of the front of the vehicle in the form of layers of dirt, sagging of the clothing fabric - they can be used to identify the vehicle
clothing cuts by headlight glasses at the points of contact in the form of linear and point damage to the material - they determine the relative position of the victim and the vehicle
inclusions of paintwork particles exfoliated from the vehicle on pedestrian clothing
inclusions of microparticles (shards) of glass, headlights - they can be used to identify the vehicle, establish the relative position of the vehicle and the pedestrian relative to each other
layers of dust, dirt in the form of prints of the tire tread pattern, which may be somewhat distorted due to fabric displacement when moving the body. Such traces 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

Slip marks on the road surface:

layers 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 road surface (asphalt, concrete). Based on such traces, it is possible to establish the fact of the body being dragged after it fell onto the roadway and the direction of displacement (arc-shaped folds are always directed with their convex part in the direction opposite to the direction of displacement)
tears in the material of clothing when moving the body on an uneven road surface. The direction of movement is determined by the location of the corner gaps (the corner is opened forward, in the direction of movement)
friction marks 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 between 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 cabin (deformation of the steering wheel, instrument panel, windshield, blood stains, etc.), location of persons after the accident.

When performing a comprehensive forensic and autotechnical examination, having studied the traces inside the car, the direction of the forces on the persons who were in it at the time of the accident, as well as the nature of the injuries, it is possible to establish the relative position of the persons who were in the vehicle at the time of the accident.

Traces resulting from a collision of the vehicle

A lot of information can be obtained by studying the damage and the final position of the vehicle. The degree of corrosion of the body (i.e. its condition), the differences in the design of the bodies, as well as the multiplicity of points that could have hit, make it difficult to calculate the forces that caused specific damage. It should be noted that even at relatively low speeds, significant damage can occur.

Damage is classified according to various criteria, requiring careful study in each specific case. First of all, the investigator must determine whether the car was damaged before or during the collision, or as a result of its forced movement after the accident, or when the victims were released from the car. Old damage sites are usually covered with rust or dried road grime. If the damage is the result of an accident, it can be classified into the following categories:

traces of direct contact of the deformed parts of the vehicle when they come into contact. Based on such traces, it is possible to tentatively imagine the relative position and mechanism of interaction of the vehicle during an accident.
prints of individual sections, details 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
abrasions, scratches, etc. resulting from vehicle contact. Such traces contain macro- and microrelief mappings 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 a passing collision
similar traces on the deformed lower parts of the vehicle that were in contact with the roadway. They can be used to judge the direction of movement of the vehicle after the collision, to clarify the place of the collision, taking into account the location of the traces left by these parts at the scene

Traces that occur when the vehicle collides with stationary objects:

damage to roadside objects such as light poles and trees, embankments and barriers. They may be some distance away from where the vehicle stopped after the accident and can therefore 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. During inspection of the roadside area, it is necessary to pay attention to possible tire prints and other traces. At the same time, it should be borne in mind that the vehicle, after hitting one or more stationary objects, can noticeably turn around, which makes it difficult to determine the initial direction of its movement. However, care must be taken when identifying the vehicles involved in the accident and the marks, as some objects, such as walls near a narrow road or passive safety equipment, have traces of previous collisions.
layers of TS paint on the surface of a stationary object. Using them, it is possible to establish the group affiliation of the car's paintwork
scratches, prints of vehicle parts on the surface of a stationary object. In the presence of such traces, it is possible to determine the direction of movement of the vehicle, to identify the trace-forming object
layering of microparticles of the vehicle and barriers. These traces are used to establish the fact of their contact interaction (the task is solved in a complex with the participation of an expert tracer)

Footprints resulting from a collision with pedestrians:

deformation of the parts of the vehicle with which the impact was made (dents on the hood, fenders and other parts of the vehicle, damage to the front pillars of the body, windshield). Based on such traces, one can judge the location of the pedestrian relative to the lane of the vehicle, and taking into account the location of the traces of the wheels of the vehicle, specify the place of collision
prints of the texture of the fabric of clothing on the plastic parts of the vehicle (bumper), traces of blood, hair of the victim. According to them, you can establish the fact of a collision, identify the vehicle that made the collision
traces of layers and delaminations on the side parts of the vehicle. Such traces indicate the fact of contact interaction between the vehicle and the pedestrian during a tangential impact.

Traces that appear on the vehicle when it rolls over:

deformation of the roof, body 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, peeling paint). These marks indicate the direction of the rollover and the change in position of the vehicle when moving after the rollover.
broken windows, broken doors. Using them, it is possible to clarify the mechanism of falling out of the vehicle of persons and objects that were in it

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 disk 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 the stability and controllability of the vehicle caused by damage (if it is previously established that they occurred immediately before the accident).

Forensic value of traces of vehicles

Information about the type and type of vehicle, its individual characteristics, direction of movement, speed, relative position of vehicles at the moment of collision, etc. is imprinted in the traces of vehicles.
The value of traces of vehicles is determined by a set of tasks that can be solved as a result of inspection and expert study of traces.
The study of traces of vehicles at the scene allows you to establish:
- group affiliation (type, brand, model) of the vehicle;
- a specific vehicle (identify the vehicle or its separate part (wheel, tire, headlight lens);
- the circumstances of the use of the vehicle (direction of movement, places of stops and braking, approximate speed of movement, length of the braking distance).
- damage to the vehicle (for example, on the right wing, destruction of the headlight lens); malfunctions of some of its units (leakage of lubricant from the rear axle housing); information about the cargo being transported, as well as about those substances that could get on the vehicles from the scene (soil particles, various other substances).

The following traces studied by transport trasology are of forensic significance: a) traces of the running gear; b) traces of protruding parts of the vehicle; c) parts and details separated from the vehicle (traces-objects).

Traces of vehicles are important in the investigation of traffic accidents, as well as crimes in which the vehicle was used to take out the stolen goods, to arrive and leave the crime scene, etc.

Along with identification tasks, diagnostic tasks are also solved on the basis of the traces of the running gear: determining the direction and mode of movement (the fact of braking, stopping, etc.). To do this, you can use the following signs displayed in the traces:

a) the tread pattern, which has herringbone-type elements, must face the open part in the direction of movement;

b) when the vehicle is moving on loose soil, the soil particles are located on both sides of the wheel track in the form of a fan, the diverging ends of which are directed in the direction opposite to the movement;

c) on an asphalt road, when crossing puddles, areas of scattered dry soil in the direction of movement, a trace of moisture (dust) remains, fading away;

d) drops of liquid (oil, brake fluid, water) falling during movement are pear-shaped, with their narrow end facing the direction of movement;

e) when moving rods, chips, branches, the ends of the latter are turned in the direction of movement;

f) when moving on the grass, its stems will be crushed in the direction of movement (in the absence of towing);

g) a stone pressed into the ground as a result of moving will have a gap in the track from the side opposite to the direction of movement;

h) on the turning section, the angle of divergence of the wheels increases;

i) the stepped relief in the traces with the sloping part of the steps facing the direction of movement (Fig. 13).

Braking is judged by the decreasing clarity of the tread pattern, by the change in pattern, and by the presence of transverse stripes. If during full braking there are traces of "skid" (slip), ^ then they are used to establish the speed of the car before it stops (autotechnical examination). To do this, measure the length of the traces of the rear wheels or the total length of the braking trace, from which the value of the vehicle base is subtracted.

Casts and photographs of traces of the undercarriage seized at the scene of the incident are sent for expert examination.

Traces of transport become the object of forensic research: 1) when investigating road accidents; 2) when the vehicle was used in the commission of a crime (theft, removal of stolen goods, corpses, murder, etc.); 3) when the vehicle itself was the object of a criminal encroachment.

Traces of this type allow: 1) to identify the characteristic features of used vehicles, to determine their group affiliation (model, type, type, etc.); 2) establish the direction of traffic, its speed and other circumstances of the event; 3) identify a specific vehicle.

Traces of vehicles include: 1) traces of the running gear (wheels, caterpillars, skids); 2) traces of the non-running part (displays of any details of the vehicle (wings, radiator), imprint of the car number (for example, on some elevation, snowdrift); 3) separated parts and particles (wood flakes from the side, fragments of headlight glass, particles of paintwork, residues of fuels and lubricants).

Dynamic traces occur during sudden braking, skidding, slipping, collisions, collisions. The braking track (skid) is usually straight, its width is equal to the width of the treadmill. The length of the braking distance depends on the speed, weight, serviceability of the vehicle, the degree of wear of the tread, the condition of the road surface, and the terrain. The braking distance can be used to determine the speed of the vehicle before braking. To static traces include traces of rolling wheels (the so-called treadmill of the movement of the vehicle).

Surface traces (layers and delaminations) are formed on the hard surface of the road (asphalt, concrete), on flat objects, on the clothes of the victim. Surface marks of a vehicle can be positive(when the relief of the protruding part of the tread pattern is displayed on the surface of the road surface) and negative(volumetric) when the mark is formed due to dirt and dyes stuck in the grooves of the tread. The relief features of the tread are most often reflected in three-dimensional traces that occur on soft ground (earth, snow). Tread depth is usually directly proportional to vehicle weight and inversely proportional to soil elasticity.

Each tire model has a specific tread width. The width of the tread (tire profile) depends on the degree of inflation of the tire, the load on the vehicle and the nature of the road surface. The width of the track can also increase due to the partial display of the side walls of the tread in it. The width of the treadmill is usually determined by the bottom of the track.

You can judge the type, model and device of the vehicle by the following features:

1) the number of axles (two, three) and the number of wheels on each of them (four, six, etc.). When driving in a straight line, the rear wheels completely or partially overlap the tracks of the front wheels. The number of axles can be determined by turning, which forms separate strips from each wheel. It is usually not possible to distinguish the tracks of a two-axle car from a three-axle one, since the wheels of the third axle follow the tracks of the second axle. The tracks of the trailer wheels also cover the tracks of the car wheels;
2) track width - the distance between the center lines of the track of the left and right wheels or between the gaps of the rear twin wheels (Fig. 24);
3) the base of the car - the distance between the front and rear (rear) axles, which is measured by traces of dents, crumbling dirt at stops, when turning using reverse gear;
4) data on the width, tread pattern, its individual features, wheel diameter, which are of particular importance in the track.

Wheel outer diameter (tire) is calculated by the length of its circumference, which can be determined by measuring the distance between any part (feature) of the running part of the tire tread, repeated twice in its track. Original formula: S = 2p x R. The diameter is measured accordingly according to the formula: D=S x 1.1: to. The circumference measured in this way is multiplied by 1.1 - the tire deflection factor and divided by k = 3.14. The result obtained, since the wheel diameter is indicated in inches, is divided by 2.54 cm.

Direction of traffic determined by a number of features (Fig. 25):

the tread pattern, having herringbone-type elements, faces the open part in the direction of movement;

deposits of dust and snow form along the tracks in the form of a fan, the sharp corners of which are directed in the direction of movement;

on an asphalt road when crossing puddles, as well as scattered dry soil, etc., a trace of moisture, dust is fading in the direction of travel;

when moving through puddles, mud and water are sprayed forward and to the sides;

drops of liquid falling from the vehicle are elongated in the direction of movement;

branches broken when moving wheels with their outer ends directed in the direction of movement;

on the turn section, the angles of divergence of wheel tracks are first formed, which are greater than the toe angles that occur at the end of the turn;

when moving on the grass, the stems of plants are tilted in the direction of movement;

stones and other objects lying in the way are shifted during a forward collision;

Rice. 24.

L- traces of a car with single rear wheels; AT- traces of a car with twin rear wheels; C - traces of a car in which single rear wheels partially overlap the traces of the front wheels: a- track width; b- the distance between the outer boundaries of the traces; d- the distance between the inner boundaries of the traces; e- wheel track width; t- the width of the combined traces of the front and rear wheels; g-g- the width of the incomplete track of the front wheels; to-to- the distance between the tracks of the paired rear wheels; z- distance between the center lines of the traces of the rear wheels; / - the distance between the outer and inner boundaries of the traces of the car

Rice. 25.

1 - splashes and dirt when moving through a puddle; 2 - trampled grass in the direction of traffic; 3 - location of dust and snow along the track; 4 - the location of the ends of the sticks broken during the move; 5- divergence angle ratios (a) and convergence (b) when turning right; 6 - relief of the bottom of the track on soft ground; 7 - drops of liquid that fell from the vehicle; 8 - gap when moving through a stone; 9 - tread angles

the braking trail is more saturated at the end of braking, while the clarity of the tread pattern disappears; On a soft road, tires push the surface layer of the ground forward when braking.

In order to conduct an identification study, a plaster cast is made from the area of the three-dimensional track, in which the individual features of the tire tread (cuts, scratches, cracks) are displayed, after appropriate fixation according to the rules of large-scale photography. The surface mark on asphalt and similar surfaces can be replicated with a sanded sheet of rubber or silicone compound.

Traces of caterpillars (tracks) consist of two lanes. The distance between their centers determines the track width of a given vehicle. This data, while taking into account the characteristic configuration of the tracks, is used to determine the model of the vehicle. In the study of traces, specific details and defects in the structure of the tracks are fixed.