Hierarchical Structure of
hierarchical structure and the scenario of road accident is reviewed by road
accident data, the database framework
within which it is stored, using multilevel statistical models (K. Senthilkumar,
analysis of accident is mostly concerned with the causal factors linked with
the incidence of accident and mapping and modelling of the accidental scenario
based on those causal factors and finally drawing out of strategic measures for
safe traffic management.
Causes of Road Traffic
most basic question that arises out of any accidental scenario is the cause or
the reason of its production. The pattern of the combined picture of behavioural factors and
associated decision-making processes are generally accepted to be the main underlying cause
of most motor vehicle collisions, injuries, and fatalities (Micheal, 2007). The use of excessive speed
is the most significant factor in most motor
vehicle collisions, injuries, and fatalities. The average traveling
speed for motor vehicles
has increased significantly especially on major roads and freeways. This change
can be said to have occurred mainly from road network infrastructural and
design improvements. At an excessive speed, there is no sufficient time
for the driver to stop the vehicle safely on any given road. Driving at speeds
over the legal limit is a common behaviour of many drivers. One speed
survey showed that just over half of drivers stayed below the
designated 60 Km/hr speed limit (Zhang et al., 2000).
installation of fixed and mobile speed cameras has led to a significant decrease
in road crashes both during day and night
time, and also on roads with speed limits varying from 60 to 110 Km/hr
(Christie et al., 2003).
and driving increases both the risk of a crash and the likelihood of death or a serious injury. The risk
of involvement in
a crash increase significantly above a blood alcohol concentration
(BAC) of 0.04 g/dl (Compton, 2002).
which establish lower BACs (between zero and 0.02 g/dl) for young/novice drivers can lead to reductions of
between 4% and 24% in the number of crashes involving young people (Shults, 2001).
of sobriety checkpoints and random breath-testing can lead to reductions in alcohol-related crashes of about
20%, and has been shown to be very cost-effective (Elder, 2002).
studies have demonstrated a positive correlation between blood alcohol concentration (BAC) and impairment
of motor coordination and cognitive performance, including the skilled
performance required to operate a motor vehicle (Voas et al., 2002).
the recent past, the role played by psychoactive substances in road safety has interesting subject. The frequent use and
misuse of these substances
along with its associated behavioural risk cannot be ignored in perspective to reduce the
high costs related to road accidents. Many reports have showed a growing and
worldwide presence of psychoactive substances in drivers involved in road accidents (Kelly et al., 2004).
impairs the skills important for driving, including tracking, psychomotor skills, reaction time and performance
especially in the first 2 hours after smoking. The main effect of marijuana was
to increase lateral movement of the vehicle moderately within the
driving lane on a highway (Berghaus et al., 2005). Surveys conducted in widely separated localities
have generally revealed
the presence of tetra hydro cannabinol (THC) in between 4 and 14% of drivers who
sustained injury or death in traffic accidents (Drummer et al., 2003). Studies have shown that alcohol and the
combination of alcohol with cannabis
significantly and strongly elevated crash culpability rates (Lowenstein et al., 2001).
fact, (an interesting fact to note), low to moderate acute doses of cocaine and
amphetamine can be
expected to increase positive mood, energy, and alertness, especially in non-tolerant
individuals. It seems likely that
abrupt discontinuation of either
drug in a chronic user could result in driving impairment (Bernhoft
et al., 2003). The use of marijuana (THC), cocaine, opiates can
reduce driving performance
et al., 2004).
A significant number of ill effects, leading to impairment
of the driving skills such as blurred vision, slow visual accommodation,
disorientation, and eye
hand coordination can be associated with the use the tricyclic antidepressants (TCAs),
e.g., amitriptyline. However, the most dangerous is the feeling of drowsiness
and sedation after such use (Koelega, 1993). Disabled psychomotor and
cognitive performance along with sedation has been found to be a production
characteristic of almost all the all first-generation antihistamines (cold and
allergy medications) as compared to the the second generation antihistamines which
are generally safe at therapeutic doses (Jay
et al., 2000).
Driver fatigue and drowsy driving covers a
spectrum ranging from driving
while clearly tired, up to episodes of “micro-sleeping” and finally
to falling asleep at the wheel.
Risk factors include lack of sleep, driving while intoxicated with
alcohol or other drugs, long periods of driving without rest, sleep
apnoea, and other medical disorders. The problem is common and widespread. It
has been estimated that more than one-third of the driving population admits to have “nodded off”
for at least a moment while driving. Most
instances tend to occur late at night, with only 9% happening between 6:00 and
11:00 a.m., whereas 28% occurred from midnight to 6:00 a.m. (Stutts et al., 2003) Typical motor vehicle
incidents that are caused by drowsy driving are single-vehicle run-off-the-road crashes and
rear-end collisions (Horstman et al., 2000).
According to Van & Donald (2001), drivers today are faced
with many problems when driving
in congested and overcrowded cities, especially being overloaded by the vast
amount of information
that needs to be continuously processed. The types of information a typical
may encounter and need to react upon are numerous and include traffic signs, traffic
signals, advertisements, horns, loud music from passing vehicles, vehicle changing
lanes, pedestrians and much more. It has been estimated that approximately 25%
of all crashes in the United States result from driver inattention or
distraction. Further the consequence of the interaction with the modern
technology also cannot be ignored. These technology-based distractions including mobile
phones, e-mail and the Internet, radio, CD and DVD players, and route
guidance systems and all may have a detrimental effect on distracted performance
of the drivers. Decrease in the rate of usage of the motor vehicle has been
found especially during weekends or at nights with an exceeded speed limit and
also when the passengers are boarded in the vehicles (Johnson, 2004). Association of a personal
hands-free mobile telephone than a handheld mobile telephone or hands-free
speaker mobile telephone with a
significantly lower additional work load has been found while driving on a highway (Matthews, 2003). According to a study conducted by Clarke et al
(2007), out of the 1106 recorded car drivers who got killed in road traffic
crashes in the year 2005 at Britain and Wales, 40% of the victims had no worn seat belts, with their average
age hanging between 17 to 29 years. Another interesting fact that got noticed
in the survey was the increase in the awareness of tying the seat bel increases
with the age of beyond 30 years. In fact, avoidance in the usage of seat belt
both by the drivers and the vehicle occupants during night, thereby resulting
death casualty in road accidents has also been found to be significantly higher
(Broughton and Walter, 2007).