Appendix 5. Characteristics of the included studies
Study
Study design
DCT type
Chiou and Chang
Observational study,
GSCT (with
(2010)
with and without
the inclusion
analysis
of yellow
interval)
Limanond et al. (2010)
Observational study,
before and after
analysis
RSCT
Observational study, on
and off analysis
CCT
Data collection
Study site: One intersection with
timer and one without timer in
Jhubei, Taiwan
Time of day for observation: 7
to 11 am on Feb. 22, 2008
Subject vehicle type: NA
Sample size: n=274
Outcome measures
(1) Percentage of
Late-stopping; (2) Range
of type II dilemma zone;
(3) Likelihood to cross
Study site: One intersection
before and after timer installation
in Taipei, Taiwan
Time of day for observation: 7
to 11 am on Sept. 7, 2007
(before-RSCT), Oct. 26, 2007
(1.5 months after-RSCT), Dec. 7,
2007 (3 months after-RSCT), and
Jan. 25, 2008 (4.5 months
after-RSCT), respectively Subject
vehicle type: Motorcycle and
passenger car
Sample size: NA
Study site: One intersection
before and after timer switching
off in Bangkok, Thailand
Time of day for observation: 10
am to 3pm Subject vehicle type:
passenger vehicle
Sample size: n=156
(1) Early start ratio; (2)
Start- up delay; (3)
Saturation headway
1
(1) Saturation headway;
(2) Saturation flow rate;
(3) Start-up lost time; (4)
Number of crossing after
yellow onset; (5) Entry
time since yellow onset;
(6) Number of Red light
violation; (7) maximum
violation time after red
onset
Findings
(1) Percentage of Late-stopping
decreased from 0.56 to 0.29, but
without statistical significance test;
(2) Range of type II dilemma zone
extended from 30 to 58 m; (3)
Crossing likelihood when facing a
green countdown of less than 10 s
significantly reduced.
(1) Reduction in early start ratio
dissipated over time; (2) Start-up
delays decreased slightly over the
longer term; (3) Saturation headway
for cars decreased during peak period,
but not off-peak hours; (4)
Cumulative start-up delay for cars
slightly decreased over time.
(1) Mean saturation headway
increased from 1.85 to 1.88 s, but
without statistical significance; (2)
Saturation flow rate slightly decreased
from 1,946 to 1,918 vehicles; (3)
Mean start-up lost time significantly
reduced from 8.32 to 6.53 s; (4) There
were no significant differences in the
number of crossing after yellow onset
or entry time since yellow onset; (5)
Number of red light violation and
maximum violation time after red
onset decreased, but without
statistical significance test.
Appendix 5. Characteristics of the included studies (Continued)
Study
Study design
DCT type
Long et al. (2013)
Observational study,
CCT
with and without
analysis
Ni and Li (2014)
Observational study,
with and without
analysis
GSCT (with
the inclusion
of yellow
interval)
Sharma et al. (2009)
Observational study,
with and without
analysis
CCT
Data collection
Study site: Two intersections with
timer and two without timer in
Changsha, China
Time of day for observation: 8
to 10 am on 2 successive sunny
workdays from Sept. 1 to Sept. 2,
2010
Subject vehicle type: Passenger
car
Sample size: n=273
Outcome measures
(1) Percentage of
aggressive cross after
yellow onset; (2)
Percentage of normal cross
after yellow onset; (3)
Percentage of normal stop
after yellow onset; (4)
Percentage of conservative
stop after yellow onset; (5)
Percentage of normal
run-red; (6) Percentage of
aggressive run-red
Study site: Two intersections with
timer and two without timer in
Suzhou, China
Time of day for observation:
4:30 to 6:00 pm on a Wednesday
and 7:00 to 9:30 am on a
Thursday in March, 2012
Subject vehicle type: Passenger
car and very limited bus
Sample size: 385 vehicles at
intersections with timer and 235
vehicles at intersections without
timer
Study site: One intersection with
timer and one without timer in
Chennai, India
Time of day for observation:
4:30 to 5:30 pm on each day of
total 7 days Subject vehicle type:
Passenger car, auto-rickshaw,
two-wheeler, and bus Sample
size: NA
(1) Rear-end collision
probability during flashing
green interval; (2)
Rear-end collision
likelihood during yellow
interval; (3) Type II
dilemma zone distribution
2
Gap time
Findings
(1) Percentage of aggressive cross
after yellow onset reduced from
10.0% to 6.1%; (2) Percentage of
normal cross after yellow onset
increased from 50.9% to 74.2%; (3)
Percentage of normal stop after
yellow onset decreased from 17.3% to
10.4%; (4) Percentage of conservative
stop after yellow onset reduced from
21.8% to 9.2%; (5) Percentage of
normal run-red increased from 3.6%
to 9.2%; (6) Percentage of aggressive
run-red increased from 3.6% to 4.3%.
(1) GSCT increased the rear-end
collision probability during flashing
green interval, especially for vehicles
in a zone ranging from 15 to 70 m; (2)
GSCT reduced the rear-end collision
likelihood during yellow interval,
especially for vehicles in a zone
ranging from 0 to 50 m; (3) Range of
type II dilemma zone shortened and
moved away from the stop line during
both flashing green and yellow
intervals.
Gap time nearly kept constant initially
and then decreased towards the end of
green light under heterogeneous
traffic conditions.
Appendix 5. Characteristics of the included studies (Continued)
Study
Study design
DCT type
Long et al. (2011)
Observational study,
CCT
with and without
analysis
Huang et al. (2014)
Observational study,
with and without
analysis
GSCT (with
the inclusion
of yellow
interval)
Data collection
Study site: Two intersections with
timer and two without timer in
Changsha, China
Time of day for observation: 8
to 10 am on 2 successive sunny
workdays from Sept. 1 to Sept. 2,
2010
Subject vehicle type: Passenger
car
Sample size: n=273
Outcome measures
(1) Proportion of stopping
after yellow onset; (2)
Proportion of crossing
after yellow onset; (3)
Proportion of red light
running; (4) Average
distance to the stop line for
stopping and crossing; (5)
Likelihood of stopping at
yellow onset; (6) Entry
time since yellow onset
Study site: Two intersections with
timer, two intersections with
flashing green (GSFD), and other
two common (CSD) intersections
in Changsha, China
Time of day for observation: 9
to 11 am and 3 to 5 pm from Oct.
15 to Oct. 22, 2012
Subject vehicle type: motorized
vehicle
Sample size: 200, 200, and 350
vehicles at common, flashing
green, and timer signalized
intersections, respectively
(1) Time point of
decision-making before
yellow onset; (2)
modelling
decision-making behavior;
(3) Range of type I
dilemma zone; (4) stop and
go decisions during yellow
interval for vehicles in
dilemma zone; (5) Red
light violation
3
Findings
(1) Proportion of stopping after
yellow onset dropped from 41.2 to
21.1 percent; (2) Proportion of
crossing after yellow onset rose from
58.7 to 78.8 percent; (3) Proportion of
red light running increased from 8.2
to 15.4 percent; (4) Most drivers in a
zone between 10 and 30 m chose to
cross after yellow onset; (5) Average
distance to the stop line for stopping
increased from 20.0 to 33.4 m; (6)
Average distance to the stop line for
crossing reduced from 10.5 to 9 m;
(7) Likelihood of stopping at yellow
onset significantly decreased; (8)
Entry time since yellow onset under
with timer condition was longer
lasting on average than that under
without timer condition.
(1) Time point of decision-making
before yellow onset under GSCT was
earlier than that under GSFD or CSD;
(2) Drivers decision- making
behaviors under three green signal
devices could be modelled by BPNN
model; (3) GSCT and GSFD reduced
the likelihood of being trapped in type
I dilemma zone than CSD; (4) GSCT
induced drivers in type I dilemma
zone to choose to cross the
intersection during yellow interval;
(5) Vehicles in type I dilemma zone
under GSCT were more likely to
violate red light; (6) Red light
violation under GSCT was less than
that under GSFD and CSD.
Appendix 5. Characteristics of the included studies (Continued)
Study
Study design
DCT type
Limanond et al. (2009) Observational study, on CCT
and off analysis
Ma et al. (2010)
Observational study,
with and without
analysis
GSCT (with
the inclusion
of yellow
interval)
Data collection
Study site: One intersection
before and after timer switching
off in Bangkok, Thailand
Time of day for observation:
10:00 to 15:00 (off-peak day
time), 20:00 to 22:00 (night time),
and 22:00 to 02:00 (late-night
time) on Apr. 25 and May 2,
2007
Subject vehicle type: NA
Sample size: NA
Outcome measures
(1) Saturation headway;
(2) Saturation flow rate;
(3) Start-up lost time;
Study site: One intersection with
timer and one without timer in
Shanghai, China
Time of day for observation: 1
to 4 pm on four weekdays in May,
2009 Subject vehicle type: NA
Sample size: n=1695
(1) Vehicular passing
speed at the stop line
during yellow phase; (2)
Vehicular speed evolution
during yellow interval; (3)
Type I dilemma zone
distribution; (4) Number of
crossing after yellow
onset; (5) Number of red
light violation
4
Findings
(1) Mean saturation headway
significantly decreased from 1.94 to
2.05 s during night time, but not
during off-peak day time and late
night time; (2) Saturation flow rate
noticeably increased from 1,756 to
1,855 vehicles during night time; (3)
Mean start-up lost time significantly
decreased during three study periods
(i.e., from 8.32 to 6.53 s during day
time; from 5.92 to 4.92 s during night
time; and 5.95 to 4.03 s during
late-night time).
(1) Mean vehicular passing speed at
the stop line during yellow phase
significantly increased from 20.5 to
26.4 km/h; (2) GSCT smoothed the
driver’s response to the phase change;
(3) GSCT effectively eliminated type
I dilemma zone; (4) Number of
crossing after yellow onset noticeably
increased from 196 to 251; (5)
Number of red light violation
noticeably decreased from 26 to 3.
Appendix 5. Characteristics of the included studies (Continued)
Study
Study design
DCT type
Sharma et al. (2012)
Observational study,
CCT
before and after
analysis
Data collection
Study site: One intersection
before and after timer switching
on in Chennai, India
Time of day for observation: 11
am to 12 pm for 10 days (five
days with timer on and five days
with timer off) Subject vehicle
type: car, bus, two-wheeler, and
auto-rickshaw Sample size: 4,914
cars, 174 buses, 7,276
two-wheelers, and 1,438
auto-rickshaws under with timer
condition; 4,311 cars, 192 buses,
6,800 two-wheelers, and 1,431
auto-rickshaws under without
timer condition
5
Outcome measures
(1) Discharge headway; (2)
Propensity of red light
violation; (3) Intensity of
red light violation; (4)
Number of red light
violation
Findings
(1) Significant change in the queue
discharge models when timer being
presented; (2) Headway of
two-wheeler significantly decreased
for first 10s of green; (3) Propensity
of red light violation decreased from
59 to 31 percent at red start, but
increased from 12 to 75 percent at red
end; (4) Intensity of red light violation
dropped from 3.32 to 2.30 vehicles at
red start and from 8.52 to 85.60
vehicles at red end; (5) CCT resulted
in an overall increase in propensity
(from 64 to 85 percent) and intensity
(from 4.69 to 5.74 vehicles) of red
light violation; (6) Number of red
light violation for two-wheelers and
cars significantly increased at red
start; (7) Number of red light
violation for two-wheelers,
auto-rickshaws and cars significantly
increased at red end.
Appendix 5. Characteristics of the included studies (Continued)
Study
Study design
DCT type
Liu et al. (2012)
Observational study,
CCT
with and without
analysis
Lum and Halim (2006)
Observational study,
before and after
analysis
GSCT
(without the
inclusion of
yellow
interval)
Data collection
Study site: Nine intersection
approaches with timer and four
without timer in Jiangshu
Province, China
Time of day for observation:
weekday peak periods Subject
vehicle type: NA Sample size:
n=6758
Outcome measures
(1) Saturation headway;
(2) Start-up lost time; (3)
discharge headway
compression
Study site: One intersection
before and after timer installation
in Singapore Time of day for
observation: four continuous
days from Sunday to Wednesday
before-GSCT installation and at
1.5-month, 4.5- month, and
7.5-month after-GSCT installation
Subject vehicle type: NA
Sample size: 74,814 vehicles
before-GSCT installation, 77,131
vehicles at 1.5-month after-GSCT
installation, 73,390 vehicles at
4.5- month after-GSCT
installation, and 78,672 vehicles
at 7.5-month after-GSCT
installation
(1) Number of red light
violation; (2) Number of
red stopping action
6
Findings
(1) Mean saturation headway for
protected left-turn movements
increased from 2.15 to 2.26 s, but
without statistical significance; (2)
Mean saturation headway for through
movements significantly increased
from 2.20 to 2.35 s; (3) Mean start-up
lost time for protected left-turn
movements significantly dropped
from 3.55 to 2.95 s; (4) Mean start-up
lost time for through movements
significantly reduced from 4.72 to
2.47 s; (5) For protected left-turn
movements, headway compression
began when 5 s remain in the left-turn
green time; (6) For through
movements, headway compression
began when 15 s remain in the
through green time.
(1) Number of red light violation
significantly reduced at 1.5-month
after GSCT installation; (2) Impact of
GSCT on the reduction in red light
violation tended to dissipate over
time, but the number of red light
violation was still below the original
value; (3) Number of red stopping
action significantly increased over the
longer term.
Appendix 5. Characteristics of the included studies (Continued)
Study
Study design
DCT type
Rijavec et al. (2013)
Observational study,
CCT
on-off-on analysis
Raksuntorn (2012)
Observational study, on
and off analysis
RSCT
Data collection
Study site: One intersection
(before and after timer turning
off, then turning on again) in
Liubljana, Slovenia Time of day
for observation: Afternoon hours
on Aug. 12 and Aug. 16-17, 2010
(timer on), Aug. 18-19 and Aug.
23-24, 2010 (timer off), and Aug.
26 , 2010 ( timer on again)
Subject vehicle type: passenger
car Sample size: NA
Outcome measures
(1) Saturation headway;
(2) Start-up lost time; (3)
Proportion of signal light
violation
Study site: Thirty intersections
before and after timer turning off
in Bangkok, Thailand Time of
day for observation: During
sunny days Subject vehicle type:
passenger car Sample size: NA
(1) Saturation headway;
(2) start-up lost time
7
Findings
(1) No significant differences in mean
saturation headway were found across
before and after timer turning off or
before and after timer truing on again;
(2) No significant differences in mean
start-up lost time were found across
before and after timer turning off or
before and after timer truing on again;
(3) Proportion of signal lights (yellow,
red, and red/yellow) increased after
timer turning off, but bounced back to
original values after subsequent
turning on, however, these differences
were not verified by statistical
significance test.
(1) No significant difference in
average saturation headway was
found before and after timer turning
off; (2) Start-up lost time significantly
decreased from 4.3 to 2.9 s, when
timer was in use.