Comparative Speed Study: A Way to Improve Road Safety Condition

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Comparative Speed Study: A Way to Improve Road Safety Condition
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Shakil M. Rifaat
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IUT JOURNAL OF ENGINEERING AND TECHNOLOGY (JET), VOL. 12, NO. 1, JUNE 2015 41
Comparative Speed Study: A Way to Improve
Road Safety Condition
Shakil Mohammad Rifaat*, Mosabbir Pasha, Mahmudul Hasan Shovon, Sajidur Rah-
man Nafis, and Md. Kamruzzaman Haque Limon
Abstract—With the development of science and tech-
nology people experience a large number of motor
vehicles which is the main and easier way of travelling
for people and carrying goods from one place to another.
Roads, highways and streets are fundamental to trans-
portation system and over 70% of passenger travel and
much of goods mover is over the highways. However,
at the same time we are sacrificing a large number of
valuable human lives or being severely injured each day
around the world. Road crashes are the major cause for
it. It is a leading cause of deaths and serious injuries.
Several studies justifies that speed is the major cause
related to the risk of getting involved in a road accident.
However, very few speed related studies done in the
developing countries context, for example, Bangladesh.
Specifically, the road safety authority of this country
does not aware how speed data can be effectively used
to enhance safety. This paper investigates the speed
scenario of a particular roadway section of Mirpur Road
as a pilot project. The speed data of various types of
vehicles that use this particular roadway were taken
for this study. To get a complete speed scenario of this
road section data were taken on both weekdays and
weekends in four different time periods that include
morning peak (8.00a.m-9.00a.m), off-peak (11.00a.m-
12.00p.m), evening peak (6.00p.m-7.00p.m) and night
time (9.00p.m-10.00p.m). Unpaired T- test analysis was
performed considering 90% confidence interval for both
equal and unequal variances. It is found that compared
with other time periods vehicle speed varies in the
morning-peak at weekdays and in the evening-peak at
weekends. The speed of car, bus and truck significantly
varies between two different days. Some measures that
demand priority consideration in improving road safety
are increasing road width, deploying traffic police in
* Corresponding author.
Shakil Mohammad Rifaat, Mosabbir Pasha, Mah-
mudul Hasan Shovon, Sajidur Rahman Nafis, and Md. Kam-
ruzzaman Haque Limon are with the Civil and Environmental
Engineering department of Islamic University of Technology
(IUT), Gazipur, Bangladesh. e-mail: [e-mail],
[e-mail], [e-mail],
kh [e-mail] and [e-mail].
Manuscript received March 12, 2015; revised May 14, 2015.
particular time periods, build speed bump, provide ad-
equate streetlight, installing optimum number of speed
limit sign etc.
Index Terms—Road crashes, Speed, speed bump, t-
test, road safety.
I. INTRODUCTION
Road crashes are a leading cause of deaths and seri-
ous injuries around the world. According to a statistics
[1], worldwide an estimated 1.2 million people are
killed in road accidents each year and as many as
50 million are injured. Projections indicate that these
figures will increase by about 65 percent over the
next 20 years unless there is new commitment to
prevention. It also said that road traffic accidents as
the 6th place (was the 9th in 1990) of a major cause of
death worldwide, will rise to become the 3rd leading
cause of DALYs (Disability Adjusted Life Years) lost
by 2020. Deaths and injuries from road crashes are
problems for both developed and developing countries.
However, the road crash scenario of developing coun-
try is much worse comparing with this of developed
countries. Over 80% of traffic fatalities occur in so
called developing and emerging countries, even though
these countries account only about one third of the
total motor vehicle fleet. Accident rate in developing
countries are often 10-70 times higher than that of
developed countries [2]. Developing countries suffer
staggering annual loss exceeding US$ 100 billion
for road accidents, which is nearly equivalent to the
double of all developing assistance [3].
Bangladesh, a developing country, is also facing
severe problems due to loss of life from road crashes.
Here more than 2,000 people are killed in road ac-
cidents every year, which are about 6 persons every
day [2]. According to Bangladesh Road Transport
Authority (BRTA), Bangladesh has a fatality rate of
55 persons per 10,000 vehicles. It is almost 25 times
higher comparing with that of most of the developed

42 IUT JOURNAL OF ENGINEERING AND TECHNOLOGY (JET), VOL. 12, NO. 1, JUNE 2015
countries, 8 times higher than that of Thailand and 3
times higher than that of India [4].
Hoque et al. [5] identified several contributing fac-
tors of road crashes in Bangladesh. The most signif-
icant factors are adverse roadside environment, poor
detailed design of junctions and road sections, ex-
cessive speeding, overloading, dangerous overtaking,
reckless driving, carelessness of road users, failure to
obey mandatory traffic regulations, variety of vehicle
characteristics and defects in vehicles. BRTA in its
investigation identified fifteen major causes of road
trauma in Bangladesh [6]. Reckless driving and over-
speeding have been reported as the most frequent
causes of accident.
A good number of studies have shown that high
speed is one of the major causes of crashes. Abegaz
et al. [7] identified that over speeding have highest
effects on the occurrence of sever and fatal crashes
and termed it a powerful predictor of crash injury
severity. Knight et al. [8] mentioned that driving at
high speed is often perceived to be less risky than drink
driving. However, they pointed out that this perception
about speeding may contribute to increase the crash
rates on rural roads involving young, local drivers.
They suggested that interventions are required in form
of educational programmes which aim to reduce the
rural road crash rate. He et al. [9] described that
in Guangdong Province, after using speed detection
equipment, motorway fatalities due to speeding in
2005 decreased by 32.5% comparing with 2004. Evans
[10] reported that a 1% increase in speed increases
the fatality risk by 412%. Soole et al. [11] found that
reductions in crash rates have been associated with the
enforcement of laws for maintaining suggested speed
limit. Van Petegem and Wegman [12] informed that
about 50% of all road traffic fatalities and 30% of all
traffic injuries in Netherlands take place on rural roads
with a speed limit of 80 km/h. Quddus [13] observed
that 1% increase in speed variation is associated with
a 0.3% increase in accident rates, ceteris paribus.
Reduced speed limit also play an important role in
crash reduction and their effect are widely discussed
in the literature [14-16].
From the above discussion it is clear that high
speed of vehicles plays crucial role on road crashes
both in developed and developing countries context.
Despite its importance very few speed related stud-
ies have been conducted in Bangladesh for the sake
of improving safety condition. Specifically the road
safety authority in Bangladesh does not know how
the measured speed of vehicles can be effectively
used for improving road safety scenario. Therefore,
the objective of the study is to demonstrate through
a case study how the speed measurement of different
vehicles can be used to improve the safety condition
on a particular roadway location.
For developing remedial measures against crashes
the traditional practice is to identify the crash hotspots
or blackspots at first. A good number of studies are
observed in the literature which basically deals with
how these crash blackspots can be identified efficiently
[17- 21]. However, the shortcomings of this approach
is that you have to wait for the crash occurrences on a
particular location and then implement remedial action
to fix them which is eventually a post active approach.
This study, on the other hand, proposes a method
which is proactive in nature. That means identify the
crash prone locations before crash occurrences and
adopt counter measure based on the finding of com-
parative speed study of different vehicles in different
time periods.
To fulfill the objective, at first the study will show
how the accident prone location can be identified from
a particular road segment by rigorous field investiga-
tion. As the road safety budget is usually limited for a
developing country like Bangladesh, priority selection
of critical locations among competing sites is required
at first. Then following works will be carried out in
case of speed measurement:
1) Measuring the speed of different motor vehicles
using a speed gun at different days.
2) Comparing average speed between different time
periods in a particular day for all vehicles.
3) Comparison of average speed between days for
a particular vehicle.
Finally, different safety measures will be proposed
based on the finding of this study to improve safety
scenario of the selected location. This study will
inform the policy makers to show a way how the speed
data can be effectively employed to improve the road
safety condition of a selected location.
II. METHODOLOGY
A. Site Selection
For better understanding the speeding characteristics
of a roadway it is necessary to study on several road-
way segments. However, due to limitation of resources

SHAKIL M RIFAAT et al.: COMPARATIVE SPEED STUDY: A WAY TO IMPROVE ROAD SAFETY CONDITION 43
TABLE 1: Comparison among six survey sites
Parameters Site1 Site2 Site3 Site4 Site5 Site6
Street light No No No No No No
Shoulder width Ok Not Ok Not Ok Ok Ok Ok
Sight distance Good Bad Good Bad Good Good
Clear road marking Not visible Not Not Not Visible Visible
Speed breaker No No No No No No
Sharp curve Less risky Risky Less Risky Less Less
Fig. 1: Considered six different sites
we have considered only a single location of a roadway
segment as a pilot project.
In this pilot project, Mirpur Road, a very im-
portant road in Dhaka city road network has been
selected which connects Mirpur area with Dhaka-
Mymensingh highway. In the preliminary survey for
choosing site location, we investigated from Kamar
para, near Abdullahpur to Rupnagar Police Station,
which is about 11 km. Six locations have been selected
after comparing with other locations on this road based
on existing safety considerations. For data collection
purpose a single location has been chosen from these
six locations. Table 1 shows the comparison among six
survey sites. The selection process of the final location
is described in brief below:
There are some common problems in these six site
locations of the roadway identified:
1) No street lights: There are no street light in
this road, so vehicles have higher chances of
involving crashes at night.
2) Less shoulder width: Recommended shoulder
width is usually as follows:
• At least 10 ft for heavily traveled and high
speed highways.
Fig. 2: Finally selected site for data collection
• At least 4 ft for (preferable 6 to 8 ft) for
low-type highways.
In many places the shoulder width does not
abide by recommended width.
3) Short sight distance: There are many sharp
curves in this roadway. Trees at both side of the
road block drivers sight distance.
4) Less distance for perception-reaction: Vehicles
move at very high speed on this road. There-
fore, longer stopping sight distance, breaking
distance, passing sight distance is required.
5) No speed limit signs: The drivers of bus, truck
and other vehicles have a tendency to over
speeding on this road as there is no restriction
of speed visible.
6) No road divider: Often the drivers of bus, truck
and other vehicles want to overtake illegally.
However, no road divider is observed.
7) No speed breaker: Theres not even a single
speed breaker in the entire roadway which in-
creases the over speeding tendency of the driver.
8) Sharp curves: There are many sharp curves
which drastically reduce the perception reaction
distance.