Transcript Slayt 1

Signalization Safety and Driver Behavior Study
with Flashing Green and Amber Time
at Signalized Intersections in Istanbul
Authors:
Ersoy Pehlivan, Sencer Oktav, Rahime Gunay
ISBAK Inc. Istanbul,Turkey
CONTENT
 Starting Point
 Signalization in Istanbul
 Purpose of the Study
 Methods & Research
 Application
 Conclusions
ISTANBUL in BRIEF
8th Largest city
:
5.4 sqkm
Population (2010)
: ~ 12,6 Million
Daily Trip
: ~ 21 M. T
Total Vehicle
: ~ 2,6 M.
Total Active Vehicle
:
Daily Addition
: ~ 400 veh. /day
Total Road Network
: 25.000 Km
1,7-1,9 M.
Daily Trips between two continents
: ~ 1.3 M.
SIGNALIZATION in ISTANBUL
STARTING POINT
A basic e-mail (tkm.ibb.gov.tr):
“….Yellow time is too short in Red Light Enforcement System (2 sec.)
I don't have enough time to stop my car. That is why, must be green
flashing application at all junctions which are equipped with Enforcement
System.”
Another phone call (44 44 154):
“…When the green starting to flash should I ready to stop? or opposite;
accelerate and pass the intersection? How the drivers will deal with this
uncertainty? “
STARTING POINT
At the beginning,
there was a difference of opinion between the Metropolitan
Municipality transportation department officials working on
road safety, signalization and enforcement systems.
“…Flashing Green, is it a sufficient way to preventing
violations? Or else the drivers will step on the gas?”
SIGNALIZATION in ISTANBUL
NO AMBER
or
NO RED+AMBER
between
RED to GREEN
in ISTANBUL
>>>
LESS STARTING
LOST TIME
SUSPECT 
PURPOSE OF THE STUDY
To examine drivers' behavior
when the signal is operated
with and without the flashing green application
as well as
when the duration of the yellow change interval is extended
at signalized intersections in Istanbul Metropoliten Area.
METHODS & RESEARCH
We know that
the approaching speed and distance to the intersection are the 2 most
important things that affect the driver’s behavior.
In addition,
The other studies showed the effects of the yellow change interval and
flashing green on stopping time at the stop line when
the drivers proceed at a constant speed.
METHODS & RESEARCH
In Austria (since 1969) , same as Israel and Cuba:
Green>Green Flashing>Amber>Red>Amber+Red>
In Spain: instead of flashing green: “Yellow+Green” is used together.
In Austria, Canada, Turkey, Mexico, Russia, Slovenia, Lithuania,
Israel
THE MESSAGE: “a flashing green light is used in intersections to indicate
that signal is going to change from green to red soon.”
In USA, France, Italy, France, Belgium and some other EU countries
Yellow+Red signal before the green was abandoned (same as Istanbul
but not as other Turkish cities).
MUTCD 2009: Chapter 4D, item D of paragraph-3 states specifically,
"A flashing green signal indication has no meaning and shall not be
used."
METHODS & RESEARCH
The drivers in Austria tend to stop earlier. Some 3% stop already during the period
covered by the flashing green and 70-80% by end of the amber (7-8 s period is
included due to the one approach in Linz with a four second amber duration).
In Germany & Switzerland only about half as large (28-35% during the 2-3 s
potential green interval).
This response leads to a longer interval during which a following car driver
cannot be sure, how the car driver in front will decide.
(H Köll, M Bader and KW Axhausen, 2002)
METHODS & RESEARCH
With Reference to Köll, Bader and Axhausen (2002):
The flashing green in Austria
is associated with a substantial increase of early stops,
produces a large option zone, where drivers can both safely stop & pass.
the dilemma zone is minimised. This large option zone generates a period
of uncertainty, where a driver following cannot easily predict, if the car in front
will stop or cross.
the choice models highlighted higher speeds and lower distances to the
stop line reduce the likelihood to stop.
No other variable had a significant impact
the specific measurement locations.
which could be separated from
METHODS & RESEARCH
AS a CONTINUING STUDY (to follow Köll, Bader and Axhausen):
8 signalized intersections on the main road (Kennedy Street)
of the Eastern part of the Peninsula in Istanbul were chosen as test
sites in both upstream (sectionB) and downstream (sectionA) directions
according to the assigned scenarios.
3 scenarios are discussed:
METHODS & RESEARCH
METHODS & RESEARCH
METHODS & RESEARCH
APPLICATION PHASE
According to the resolution:
Implemented in 1860 signalized intersections in 3 weeks.
 Flashing green was terminated and the duration of yellow
change interval is extended to minimum 4 seconds.
 Yellow change interval time was extended from a minimum
of 2 seconds to 3 seconds.
 Duration of the yellow change interval was increased from
3 seconds to 4 seconds where the "Red Light Enforcement"
application was used.
APPLICATION PHASE
APPLICATION PHASE
Eng. version:
Screen Savers
Turkish version:
CONCLUSIONS-1
experimental field results have shown that;
 NO NEGATIVE EFFECTS of TERMINATING the GREEN
FLASH on CAPACITY of INTERSECTIONS
 NO SIGNIFICANT DECREASE in nr of VEHICLES
PASSING THROUGH DURING the GREEN PERIOD and
CONVERSELY, INCREASE from 1-5 %.
CONCLUSIONS-2
experimental field results have shown that;
RED-LIGHT VIOLATIONS DECREASED from about 0.52% to about 0-0.7%.
VEHICLES PASSING DURING the YELLOW-CHANGE
INTERVAL INCREASE from 0.5 to 2%
PROPORTIONALLY with the EXTENSION of the YELLOW
CHANGE INTERVAL.
CONCLUSIONS
CATEGORY
SAFETY
CRASHING RESULTS
INTERSECTION CAPACITY
UTILIZATION
DRIVER COMFORT
DRIVER BEHAVIOUR
USE with ENFORCEMENT
SYSTEM
BENEFIT
LOSS
DECREASE a nr of RIGHT-ANGLE
ACCIDENTS
DECREASE A NR of REAR-END
ACCIDENTS (1)
DECREASE the ACCIDENTS
with DEATH & INJURY
NA
NA
REDUCTION USE of GREEN TIME (2)
INCREASE the DURING of
DECISION-MAKING
DIFFICULTY of PREDICTION of FRONT
DRIVER's STOP/PASS DECISION
INCREASE the PREPERATION TIME
to STOP (good driver)
INCREASE APPROACHING SPEED
(bad driver)
DECREASE the VIOLATIONS
INCREASE VIOLATIONS
in OTHER INTERSECTIONS
(*1) A nr of rear-end accidents increases a nr of more dangerous right-angle accidents.
(*2) Because of tendency to postpone.
CONCLUSIONS
:(
No complaints (zero) has been reported.
@
A descriptive e-mail has been written out for the
citizens who have a complained about this issue.
TAXI
Discussed with the taxi drivers working near the study
area. Positive feedbacks are noted about increasing
of yellow time. They agreed that the benefits of green
flashing are exaggerated.
Dissemination: Final Report was sent to the other
transportation departments.
This study has been proven that the extension of the
yellow time is much more effective on drivers than
the flashing green.
Thank You,
Goshinsetsu Ni Arigatoo
Ersoy Pehlivan
www.isbak.com.tr
References:
•“Driver Behavior under the Green Signal Countdown Information”. http://ir.lib.ncku.edu.tw/bitstream/.pdf
•“H Köll, M Bader and KW Axhausen ,2002, Driver behavior during flashing green before amber: A comparative study”.
http://ecollection.library.ethz.ch/eserv/eth:25449/eth-25449-01.pdf , Zurich, Swiss
•“Non-motorized Vehicle Drivers Behavior with Flashing Green and Green Countdown at Intersections: A Comparative
Study”. //ftp.hsrc.unc.edu/pub/TRB2011/data/papers/11-4220.pdf.
• MUTCD, 2009, FHWA, USA