ITE Journal January 2018 - 44

Variable Driver Responses
to Yellow Indications:

An Operational Challenge and Safety Concern
By Hameed Aswad Mohammed, David S. Hurwitz, Ph.D.,
and Edward Smaglik, Ph.D., P.E.

I

shutterstock/Sorranop

SAFETY

ntersections require a variety of crossing and turning maneuvers resulting
in potential conflicts between vehicles, pedestrians, and bicycles that can
contribute to crash outcomes. Although intersections represent a small portion of the
roadway network, they are overrepresented in crash statistics.1 The National Highway

Traffic Safety Administration reported in 2014 that 32,675 people died and 2,338,000 people were
injured in motor vehicle crashes in the United States, and at signalized intersections, there were
4,825 fatal crashes and 855,000 injury crashes.2
Section 4D.26 of the Manual on Uniform Traffic Control Devices
(MUTCD) explains that the Circular Yellow (CY) indication is used
to warn drivers that the Circular Green (CG) indication has ended
and that the Circular Red (CR) indication will be presented next.
Additionally, it states that the yellow change interval should have a
duration between 3-6 seconds with longer intervals used on higher
speed approaches.3 Yellow change intervals have been identified as
potential challenges for both drivers and traffic engineers because
at the CY onset, drivers must choose to slow down and stop at the
stop line, or to proceed through the intersection.4 This decision
can be difficult as the duration of yellow change intervals are not
determined in a consistent manner, the laws governing driver
response to CY indications vary across states, and because drivers'
judgement of speed and distance are imperfect.5
In 2013, the National Coalition for Safer Roads reported 697
people were killed and an estimated 127,000 people were injured in
red-light running (RLR) crashes. Extensive research on signalized
intersection safety in different countries has been performed and
much of this work has considered driver's decisions to stop or
proceed through an intersection during the yellow change or red
clearance interval.6-11
44

J a n uar y 2018

it e jo u rn al

Background
Van der Horst and Wilmink (1986) suggested that the tendency
of drivers to stop on yellow is based on driver behavior, the consequences of stopping, and the consequences of not stopping.12 Driver
decision making at the onset of the CY is complicated and affected
by several variables including travel time, speed, type of intersection
control, headway, coordination, approach grade, and yellow change
interval duration. The consequences of stopping abruptly at the onset
of the CY are most commonly associated with the threat of a rear-end
crash (especially at higher deceleration rates in closely spaced traffic)
and delay, while the consequences of not stopping relate to the threat
of right-angle crash (if the driver proceeds through the intersection
when there is not adequate time to clear the intersection before
conflicting movements are released) and of citation.13
One of the fundamental problems at a signalized intersection is
the dilemma zone. There are two general classes of dilemma zone
conflicts, Type I and Type II. The Type I dilemma zone describes the
possibility that a motorist presented with CY while approaching a
signalized intersection may not be able to safely go through the intersection or stop before the stop line. Several factors can contribute to
creating this scenario: intersection design, errors in signal timing,



Table of Contents for the Digital Edition of ITE Journal January 2018

President’s Message
Director’s Message
Introducing the 2018 ITE International Board of Direction
Introducing the 2018 LeadershipITE Class
Your ITE Councils: An Overview of the ITE Councils in 2018
People in the Profession
ITE News
Member to Member: Congratulations to ITE’s Three New Honorary Members
Where in the World?
Calendar
Industry News
New Products
ITE Adopts 2018–2020 Strategic Plan
Finding the Courage to Lead the Way
Providing Vehicular Cyclists with Routine Accommodation in the United States as Part of Complete Streets
Variable Driver Responses to Yellow Indications: An Operational Challenge and Safety Concern
Professional Services Directory
ITE Journal January 2018 - 1
ITE Journal January 2018 - 2
ITE Journal January 2018 - 3
ITE Journal January 2018 - President’s Message
ITE Journal January 2018 - 5
ITE Journal January 2018 - Director’s Message
ITE Journal January 2018 - 7
ITE Journal January 2018 - Introducing the 2018 ITE International Board of Direction
ITE Journal January 2018 - 9
ITE Journal January 2018 - 10
ITE Journal January 2018 - 11
ITE Journal January 2018 - Introducing the 2018 LeadershipITE Class
ITE Journal January 2018 - 13
ITE Journal January 2018 - 14
ITE Journal January 2018 - 15
ITE Journal January 2018 - 16
ITE Journal January 2018 - 17
ITE Journal January 2018 - Your ITE Councils: An Overview of the ITE Councils in 2018
ITE Journal January 2018 - 19
ITE Journal January 2018 - People in the Profession
ITE Journal January 2018 - ITE News
ITE Journal January 2018 - Member to Member: Congratulations to ITE’s Three New Honorary Members
ITE Journal January 2018 - 23
ITE Journal January 2018 - 24
ITE Journal January 2018 - 25
ITE Journal January 2018 - 26
ITE Journal January 2018 - 27
ITE Journal January 2018 - Calendar
ITE Journal January 2018 - New Products
ITE Journal January 2018 - 30
ITE Journal January 2018 - 31
ITE Journal January 2018 - ITE Adopts 2018–2020 Strategic Plan
ITE Journal January 2018 - 33
ITE Journal January 2018 - 34
ITE Journal January 2018 - Finding the Courage to Lead the Way
ITE Journal January 2018 - 36
ITE Journal January 2018 - 37
ITE Journal January 2018 - Providing Vehicular Cyclists with Routine Accommodation in the United States as Part of Complete Streets
ITE Journal January 2018 - 39
ITE Journal January 2018 - 40
ITE Journal January 2018 - 41
ITE Journal January 2018 - 42
ITE Journal January 2018 - 43
ITE Journal January 2018 - Variable Driver Responses to Yellow Indications: An Operational Challenge and Safety Concern
ITE Journal January 2018 - 45
ITE Journal January 2018 - 46
ITE Journal January 2018 - 47
ITE Journal January 2018 - 48
ITE Journal January 2018 - 49
ITE Journal January 2018 - Professional Services Directory
ITE Journal January 2018 - 51
ITE Journal January 2018 - 52
ITE Journal January 2018 - Outsert1
ITE Journal January 2018 - Outsert2
ITE Journal January 2018 - Outsert3
ITE Journal January 2018 - Outsert4
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