Due to heavy casualties of human life on roads, in every country each year, extensive investigative research works have been done and are still being done, on the possible preventive aspects. Road traffic accidents involve a good many complexities which to a large extent is known to all concerned. But, in practice the investigation of individual cases is far from satisfactory, rather often it is just perfunctory in nature and it is more so in countries like ours.
The investigation of road traffic accident cases involve the following purposes,
1. To identify the cause of accident,
2. To allow adequate compensation to the victim, if he is alive, or the next-of-kin, if the victim is dead.
3. To punish the offender, if any offence is involved.
4. To search guidelines towards prevention, of future accidents.
For these purposes, road traffic accidents should be investigated by a team of experts which, in addition to an experienced investigating police officer, should also include automobile, expert and medicolegal expert.
The investigation should include,
1. Collection of history.
2. Examination of the deceased or the injured.
3. Examination of the vehicle /vehicles involved in the accident.
4. Examination of the spot or place of occurrence of the accident.
Causes of vehicular accidents —
Accidents may occur due to the following causes —
1. Fault of the victim.
2. Fault of the driver.
3. Fault of the vehicle.
4. Fault of another vehicle, not involved in the accident.
5. Bad road condition.
6. Wrong signalling.
7. More than one of the above causes.
A medical man is not the proper man to investigate on all the 6 aspects. However, by virtue of his knowledge to interprete different injuries from different angles, he can provide many informations, which help to come to a final conclusive opinion in many regards. Not only that, visit of the place of occurrence by the medical expert, who has examined or will examine the deceased or the injured, can be very much helpful to reconstruct the circumstance of the accident.
Examination of the dead victim (postmortem examination) –
The postmortem examination should include examination of the body of the victim, examination of the clothing and any other material, if sent along with the dead body.
Examination of the clothing is important and the autopsy surgeon while doing the same, should try to find out and note the recent tears, grease mark, blood stain, soil, mud or any other stain, if present on clothes.
Examination of the body should be carried on as any other case of death due to injury. Grease marks, blood stain and stain due to soil, mud, sand etc. should be noted with care, as to their number, size and placement. Proper recording of the injuries is very much important for solving many questions which arise in a road traffic accident case.
Injuries and their interpretations in vehicular accident cases –
Road traffic injuries are blunt force injuries with forceful impact. According to the manner of production, they have three distinct types – According to the sequence of occurrence these are –
1. Primary impact injuries
2. Secondary injuries
3. Secondary impact injuries.
Primary impact injuries –
Primary impact injuries are caused when the vehicle hits the victim say a pedestrian, for the first time, to knock him down. These injuries are very much important to detect the offending vehicle, because, being the result of the impact by the vehicle, these injuries may bear the design of the part of the vehicle causing the injuries, in the form of imprint abrasion or patterned bruise. Thus, if the front of the vehicle strikes the body, the design of the grill of the vehicle may be imprinted on the body of the victim. The height of the primary impact injury on the body of the victim by some particular part of the body of the vehicle may give an idea about the height of the vehicle.
Secondary injuries –
These injuries are sustained by the victim after being knocked down by the vehicle, due to fall and friction or impact with the ground. That is why, detail examination of these injuries may help to detect some sand, soil or gravel on the injuries which help as evidence to link the place of occurrence with the injuries. The injuries may be any of the hard blunt force injuries. Among abrasions, grazed abrasions and among lacerations, stretched laceration are most common due to friction with the ground.
Secondary impact injuries –
These injuries are the result of impact between the body and the vehicle for the second time. When, after the primary impact, the victim is thrown forward and falls on the ground in front of the vehicle, if the vehicle is still in motion, then the wheels of the vehicle will run over the victim. Hence secondary impact injuries bear the tyre marks of the wheels. Run over may be caused by the front or the back wheels. Avulsion laceration is the most frequent injury, caused due to run over by the vehicle.
However, according to the type of the victim, these injuries will have various presentations and effects.
A. Injuries sustained by a pedestrian and interpretations of these injuries –
The distribution of the primary impact injuries will vary according to whether he was moving along the direction of the vehicle or against it, or if he was crossing the road at the time of being knocked down, and if so, whether with the offending vehicle coming from his right or left. Sometimes, the level of the primary impact influences, at what distance and in which position, the body will strike the ground. Thus, at times, the primary impact influences some features of the secondary injuries. Though, primary impact injuries are mostly caused by the front of the vehicle, it can also be caused by the sides of the vehicle, e.g., when the vehicle takes an acute turn or when a person strikes the side of a running vehicle. Depending on the part of the body of the vehicle and the relative, direction of movements of the victim and the vehicle, the type, size, shape, site and direction of the injury will vary. From the force of impact point of view, irrespective of the relative direction of the movement of the victim and the vehicle, the speed of the victim is so negligible in consideration to that of the vehicle that, to explain the injuries, the victim can be taken as being in a static position or in a state of inertia of rest. Hence, in case of impact over the head, the skull cage will move first and will, in its course, strike the still static brain, causing injury of the brain against the site of impact. Similarly, the skull will come to a static position first, when the brain will be still in a state of motion. This will cause another injury on the surface of the brain at a place diagonally opposite to the site of the impact. The. injury at the site of impact is called coup injury and the injury caused at a place diagonally opposite to the site of the impact, is called the contre-coup injury. In case, the head is struck at an angle, then there will be a shearing movement of the brain inside the skull cavity. In such a case, there will be larger contre-coup injury which may not be restricted on the opposite side of the impact, because, the shearing movement will cause friction of the brain with the uneven inner surface of the skull bone.
Pedestrians are the single largest group of victims of road traffic accidents.
B. Injuries sustained by occupants of vehicles –
Occupants of the vehicle who fall victims of an accident, may be the occupants of another (offended) vehicle, or may be the occupants of the same (offending) vehicle.
The offended vehicle may be a slow moving or fast moving, one, may be a two wheeler or a four wheeler and may be standing, moving in the direction of the offending vehicle or against its direction. In case of a traffic accident, injury to the victim will depend not only on these factors but also on the exact location where the victim was sitting at the time of the accident, i.e., whether he was sitting in the front row or rear row.
1. When the victim is on a slow moving, light, two wheeler vehicle like a bicycle, and if he is moving again the direction of the offending vehicle, then due to impact, his bicycle is likely to be smashed or grossly damaged. For him, the effect will be as if his forward inertia of motion is higher. He will have serious impact in the frontal aspect of his body with the anterior parts of the vehicle. In other circumstances, if he is not thrown away of his bicycle, then he will be knocked down and may be run over if the vehicle does not break the speed in the meantime. If the victim was running on a bicycle ahead of the offending vehicle and in the same direction then, due to the impact of the vehicle he may be thrown a few feet ahead on or outside the road. Thus in the first instance in such a case, the victim may not sustain any primary impact injury. However, he will sustain gross secondary injuries due to forceful fall on the ground and then he may also sustain secondary impact injuries, if he is run over by the vehicle after the fall. However, the back part of the bicycle will bear the effect of the primary impact. The danger for the victim on a bicycle in an impact with a moving automobile vehicle is that, even if the victim does not sustain any primary or secondary impact injury, chances of fatality remains high because, the head remaining unprotected may sustain fatal injury, in case the head strikes the ground when thrown ahead by the automobile.
If the cyclist, strikes a standing vehicle then ordinarily there should not be any serious injury. He may sustain injuries due to impact with the vehicle but there will not be any secondary injury or secondary impact injury.
2. If victim’s vehicle is a two wheeler and speedy one, then face to face collision will cause infliction of three types of injuries. If the two, wheeler is moving in the direction of the offending vehicle, obviously, the force of impact will be less which will depend on the speeds of both the vehicles. In these cases, maximum danger lies with the injuries sustained on head which may be directly hit by the vehicle or may itself strike the ground after being knocked down. The head or for that purpose any part of the body may be crushed subsequently by being run over by the wheels of the offending vehicle. Different types of helmets are available to absorb the force and their uses are recommended to avoid fatal head injury of the users of these two wheelers. In some states of this country, it is mandatory to use helmets by the users of two wheelers. In scooters or motor-bikes, the driver is more vulnerable in a head-on-collision, and the back seater, when the two wheeler is struck from the back by a vehicle moving in the same direction. If the two wheeler hits a standing heavy automobile, then he (the rider) may sustain fatal injuries depending on the speed of the two wheeler and part of his body facing the impact.
3. When the offended vehicle is a three wheeler – Three wheeler vehicles may be a cycle rickshaw or an auto-rickshaw. Both these vehicles being partly covered, provide minor degree protection from another vehicle which is not moving very speedily. But the protection being minimum, may not be helpful when the offending vehicle is a heavy one and runs at a very high speed. The occupants of the three wheeler may be thrown out of the vehicle , and are susceptible to any kind of injury. Primary impact injuries may be sustained with the inner parts of the three wheelers. Three wheeler vehicles are less stable when on move and may get toppled, if hit by speedy heavy vehicles or when they themselves, take acute turn with high speed. Type of wounds produced, when the victims are not dislodged from the vehicle, will be in some way similar with those sustained by inmates of four wheelers but the degree will vary.
4. In case of hand pulled cart, injuries will be similar to those sustained by the pedestrian victims, except that, in some cases the cart puller may not sustain any impact injury from the offending vehicle, if the puller is on the other side of his cart.
5. In case of a four wheeler, when the accident occurs face to face, the intensity of the impact is much more than when the offensive vehicle strikes the offended vehicle from behind, both running in the same direction. In any case, the front seat occupiers can anticipate the accident immediately before the accident occurs. As a result of this, the front seat occupiers react in a way which causes them to sustain certain injuries which they would have not sustained if they would have been in the rear row. Further, the inner structure of a vehicle is different in front and back, which causes difference in the site and type of injuries which the occupants suffer from.
Injuries sustained by the occupants of a four wheeler –
The driver – The driver, by virtue of his position sustains certain injuries which others don’t. His body being in the inertia of motion and the vehicle being in a state of rest just when the collision occurs, his body moves forward. His forehead strikes the glass screen, his chest strikes the steering wheel, his knees will strike the dash-board and his reflexly straightened legs may sustain fracture of the calcaneum or the tibia of either or both sides.
The other front seaters – The injuries sustained will be same as in case of the driver except that, injury due to the steering wheel will not be there and depending on the position of the legs, injuries over the two legs will also be different.
Injuries sustained by the rear seat occupiers –
Injuries sustained by the rear seat occupants will be somewhat different from those sustained by the front seat occupants. There is no glass screen for the forehead and no dashboard for the knee and leg to strike against. Instead, the forehead may strike the back side of top of the front seat and the knee may strike the back of the body of the front seat.
If the offended vehicle is struck from behind by a vehicle moving in the same direction or if the offended vehicle was static and struck from behind by a moving vehicle, then there may be impact injury on the back of the head of both front and rear sitters due to the impact of the back of the head with the top of the back of the seat. There may be dislocation of the spines. But there is no chance of injury due to glass screen, dash board or steering wheel. These are due to the fact that, a motion is either initiated or the motion is accelerated in the body of the offended vehicle, the bodies of the occupants being either in a state of inertia of rest or in a state of motion at a lower effective velocity because, either the offended vehicle is static or it moves in the same direction at a comparatively slower speed.
Examination of the place of occurrence –
Though, generally the autopsy surgeons or the doctors who examine the injured persons are not included in the team which undertakes examination of the place of occurrence of the accident, to include them would be ideal. This is because, being the person to interprete different injuries and identify the primary impact injuries he can contribute much to the spot investigation by explaining the relative position of the victim and the offending vehicle. In other words, he can help to a great extent to reconstruct the circumstance of occurrence of the accident. Unfortunately, in this country, we don’t have yet the infrastructure for such a coordinated team work.
Examination of the offending vehicle, the road condition, wrong signalling, collection of the story of the accident from the eye witnesses, are not the job of the doctor in any way. But in the interest of proper investigation, in many cases the doctor should have knowledge of the result of these aspects of investigation and enquiry.
It is obvious that, in road traffic accident cases, the responsibility may lie on the driver of the offender vehicle, faulty mechanism of the vehicle, the pedestrian victim, the offended vehicle, bad road condition, wrong signalling or on a third vehicle. Of all these, factors related to the responsibility of the driver and the pedestrian victims have been included under the purview of the present discussion.
Responsibility of the driver of the offender vehicle –
Apart from the lack of driving skill and knowledge of the mechanism of the vehicle, which do not come under the purview of the present discussion, some other defects or short-comings of the driver of the offender vehicle, may be best considered by a doctor. These are:
1. Whether the driver was intoxicated. Alcohol adversely affects the driving capacity in many ways.
1. Alcohol affects the visual acuity.
2. It also affects the alertness.
3. It blurs the sensory perception.
4. It delays the reflex response.
5. Capacity of judgement is diminished.
6. It gives disproportionate overconfidence.
Due to its effect on the visual acuity, assessment of the position of another vehicle or the road turnings may be wrong. Due to loss of acuity of colour vision, signals on roads may be wrongly interpreted. Due to diminished alertness, the driver may not act immediately or properly when, say for example, all on a sudden he faces an acute curve or another vehicle in front. Blurring of the sensory perception may result in over-pressing of the accelerator and over-oscillation of the steering wheel. If the reflex response is delayed, then the driver cannot react in time in emergency circumstances. Safe driving needs quick judgement and action. Overconfidence makes the driver reckless and rough and rash driving is the result which increases the risk of accident.
For drivers, different countries have specified upper permissibly limit of blood alcohol. But in our country there is nothing specific in this regard. To assess the blood level of alcohol of drivers, road side test of expired air of drivers is possible with the help of breathanalyser or alcometer.
2. Heart disease in drivers – Sudden cardiac infarction or coronary ischaemia of the drivers has been claimed to be the cause of vehicular accidents in some cases. But it is probably rightly argued that cardiac infarction or ischaemia should not be regarded as a factor to make an accident inevitable. It is also a question, how many of the deceased drivers meet the accidents due to heart attack and in how many of them heart attack precipitates due to apprehension of an imminent accident. No extent of thorough postmortem examination and tests can decide this matter, in absolute term.
3. Defects of visual and hearing systems – Cataract or deafness reduces the driving capacity by limiting the visual and hearing capacities. Thus, the driver may not properly see the reflection of picture of a bus in the mirror or he may not hear the sound of a horn, which are very much essential for safe driving of a vehicle.
4. Physical and mental exhaustion of a driver makes the driving accident-prone.
5. Epilepsy – This condition makes the service of a driver very much risky.
These factors also act in pedestrian victims who meet with an accident. Hence, in resolving a case of compensation, or in the criminal side of a vehicular accident case, the role of a doctor is definitely more than conduction of post mortem examination in a perfunctory way.