What are the causes of road traffic accident?

There are three causes of road traffic accident

1. Human factors

Human factors in vehicle collisions include all factors related to drivers and other road uses that may contribute to a collision. Examples include driver behavior, visual and auditory acuity, decision-making ability, and reaction speed.

A 1985 report based on British and American crash data found driver error, intoxication and other human factors contribute wholly or partly to about 93% of crashes.

Drivers distracted by mobile devices had nearly four times greater risk of crashing their cars than those who were not. Dialing a phone is the most dangerous distraction, increasing a driver's chance of crashing by 12 times, followed by reading or writing, which increased the risk by 10 times.

2. Road design

A 1985 US study showed that about 34% of serious crashes had contributing factors related to the roadway or its environment. Most of these crashes also involved a human factor. The road or environmental factor was either noted as making a significant contribution to the circumstances of the crash, or did not allow room to recover. In these circumstances it is frequently the drive who is blamed rather than the road; those reporting the accident have a tendency to overlook the human factors involved, such as the subtleties of design and maintenance that a driver could fail to observe or inadequately compensate for

Research has shown that careful design and maintenance, with well-designed intersections, road surfaces, visibility and traffic control devices, can result in significant improvements in accident rates.

Individual roads also have widely differing performance in the event of an impact. In Europe there are now EuroRAP tests that indicate how "self-explaining" and forgiving a particular road and it s roadside would be in the event of a major incident.

In the UK, research has shown that investment in a safe road infrastructure program could yield a 1/3 reduction in road deaths, saving as much as £6 billion per year. A consortium of 13 major road safety stakeholders have formed the Campaign for Safe Road Design, which is calling on the UK Government to make safe road design a national transport priority. 

3. Vehicle design and maintenance

Seat belts

Research has shown that, across all collision types, it is less likely that seat belts were worn in collisions involving death or serous injury, rather than light injury; wearing a seat belt reduces the risk of death by about 45 percent.

Seat belt use is controversial, with notable critics such as Professor John Adams suggesting that their use may lead to a net increase in road casualties due to a phenomenon known as risk compensation. However, actual observation of driver behaviors before and after seat belt law dose not support the risk compensation hypothesis. Several important driving behaviors were observed on the road before and after the belt use law was enforced Newfoundland, and in Nova Scotia during the same period without a law. Belt use increased from 16 percent to 77 percent in Newfoundland and remained virtually unchanged in Nova Scotia. Four driver behaviors (speed, stopping at intersections when the control light was amber, turning left in front of oncoming traffic, and gaps in following distance) were measured at various sites before and after the law. Changes in these behaviors in Newfoundland were similar to those in Nova Scotia, except that drivers in Newfoundland drive slower on expressways after the law, contrary to the risk compensation theory.

Maintenance

A well-designed and well-maintained vehicle, with good brakes, tires and well-adjusted suspension will be more controllable in an emergency and thus be better equipped to avoid collisions. Some mandatory vehicle inspection schemes include tests for some aspects of road worthiness, such as the UK's MOT test or German TUV conformance inspection.

The design of vehicles has also evolved to improve protection after collision, both for vehicle occupants and for those outside of the vehicle. Much of this work was led by automotive industry competition and technological innovation, leading to measures such as Saab's safety cage and reinforced roof pillars of 1946, Ford's 1956 Lifeguard safety package, and Saab and Volvo's introduction of standard fit seat belts in 1959. Other initiative were accelerated as a reaction to consumer pressure, after publications such as Ralph Nader's 1965 book Unsafe at Any Speed accused motor manufacturers of indifference towards safety.

In the early 1970s British Leyland started an intensive program of vehicle safety research, producing a number of prototype experimental safety vehicles demonstrating various innovations for occupant and pedestrian protection such as air bags, anti-lock brakes, impact-absorbing side-panels, front and rear head restraints, run-flat tires, smooth and deformable front-ends, impact-absorbing bumpers, and retractable headlamps. Design has also been influenced by government legislation, such as the Euro NCAP impact test.

Common features designed to improve safety include thicker pillars, safety glass, interiors with no sharp edges, stronger bodies, other active or passive safety features, and smooth exteriors to reduce the consequences of an impact with pedestrians.

The UK Department for Transport publish road casualty statistics for each type of collision and vehicle through its Road Casualties Great Britain report. These statistics show a ten to one ratio of in-vehicle fatalities between types of car. In most cars, occupants have a 2-8% chance of death in a two car collision .