Assessing the Effect of Digital Countdowns at Signalized Intersection in Addis Ababa
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Date
2019-10
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
Signalized intersections are important elements of urban road networks, and their efficiency and
safety
significantly
impact
the
performance
of
the
entire
roadway
network.
There
are
different
educational,
enforcement
and
engineering
measures
that
are
attempted
to
improve
safety
and
efficiency at a signalized intersection.
A traffic signal countdown timer is an engineering device
that displays the remaining time, typically in seconds, of the current signal phase. Because of the
difference in drivers behavior
e,
different
previous studies associated with the
effects
of
signal
countdown
has
different
outcome,
and
this
study
tries
to
assess
the
effect
of
signal with countdown on intersection safety and efficiency on the selected intersections located
in
Addis
Ababa.
For
this
research
matter,
the
researcher
selected
six
intersections
in
Addis
Ababa, three with a countdown timer and the rest three without countdown timer.
Data collection was done using video recording and
driver’s
attitude survey
from the end-users.
To measure intersection safety and efficiency
startup lost time, red light violation, dilemma zone,
and the driver's decision were identified.
Startup
lost time was estimated and found that the red
signal countdown helped to reduce the startup lost time. Green signal countdown (GSC) and Red
signal countdown (RSC) affects
the red light violations by increasing violations at the end of red
and decrease at the end of yellow. The presence of signal countdown enlarged the range of type
II dilemma zone at the onset of yellow. A binary logistic regression model is developed to study
the
effect
of
significant
factors
on
driver’s
decision
making;
and
distance,
approach
speed,
remaining
time,
and
signal
conditions
were
found
statically
significant
to
predict
driver’s
probability to stop or cross the intersection after onset of yellow.
In signal with countdown, the
driver’s decision to cross is smaller than
the intersection without countdown. From the
driver’s
attitude survey,
it was
found signal with countdown is the most recommended
in order to reduce
traffic
crashes
and
to
maximize
traffic
efficiency
by
improving
driver’s
decision
making.
Additionally,
it
is
found
that
the
most
dominating
reasons
of
red
light
violation
in
signal
with
countdown are to save time, if there is no traffic police, inadequacy of allocated green time and
carelessness towards crash.
Description
Keywords
Countdown, Dilemma zone, Drivers behavior, Red Light Violation, startup lost time