ITE Journal - March 2021 - 33

Curb Markings 

Signal Color Standards

Section 3B.23 of the MUTCD provides guidance for curb
markings. " Local highway agencies may prescribe special
colors for curb markings to supplement standard signs for
parking regulation. " 1
This opens the potential for using colors that are confusing
to colorblind road users, and some cities tend to over-rely on
the curb markings to convey parking regulations. The MUTCD
requires signs as the primary regulatory device, but sometimes
the sign is not in place while the painted curb remains, adding to
the confusion.
Faded red curb markings look like faded grey concrete to
some colorblind drivers seeking a parking space, yet these same
drivers can receive a citation or have their vehicle towed for
parking here. For example, signs in Seattle, WA, USA state, " You
may not park, even temporarily, in a Tow-Away Zone. Vehicles in
a Tow-Away Zone are subject to fines and immediate removal and
impound. " 2

The MUTCD provides details about traffic signal colors in
Chapter 4:1

At signalized intersections, color alone is used to distinguish
between opposing messages. 
Red. A circular red indication means STOP. It is typically
placed on the top of a 3-colored signal, with yellow in the middle
and green at the bottom. Unless it's not.
Yellow.  Officially, the amber/yellow indication conveys
caution for the upcoming red indication. To some, it results in
acceleration through the intersection.
Green. The most complex of the indicators, a green ball
sometimes means GO, but it can also mean other things. If
you're traveling straight, Green Means Go. If you are turning
right, Green Means Yield to adjacent pedestrians who have a
WALK signal at the same time. If you are turning left, green can
mean many different things depending on conditions.
Of course, this assumes all drivers can recognize the
difference between red and green, or at least know that green
is at the bottom location of the signal (unless it's not).

The manual also standardizes the placement of those red,
yellow, and green indications and specifically mentions colorblind
road users! It is helpful to know that the red, yellow, and green
indications should be in different places-red on top, yellow in
the middle, and green on the bottom. As colorblind drivers, we
use the movement of the indication (such as the green-to-yellowto-red phase change occurring up the signal face) as much as the
colors themselves.
However, after providing clear standards and reasoning, the
MUTCD allows for these exceptions:

Horizontal Signal Placement
4D.10 In each horizontally-arranged signal face, all signal
sections that display red signal indications shall be located to
the left of all signal sections that display yellow and green signal
indications.1

Tilemahos Efthimiadis/Flickr Commons

Signalized Intersections

4D.06.05 Each circular signal indication shall emit a single color:
red, yellow, or green. 4D.08. Standardization of the number
and arrangements of signal sections in vehicular traffic control
signal faces enables road users who are color vision deficient to
identify the illuminated color by its position relative to other
signal sections.

What Colorblind Drivers See
The author's personal experience with traffic signals includes the
following issues:
ƒ	 White Means Go? Green signal indications look white to
me-the same color as nearby street lights and lighting of
nearby homes or businesses. Signals mounted on pedestals
at intersection corners (instead of overhead) cause me
problems, especially at night and in downtown areas.
ƒ	 Yellow Means Go? Some versions of LED green and
yellow indications look very similar to me, and to other
colorblind drivers.

Figure 5. Horizontally-mounted signals.
Horizontally-installed signals can make identifying red, yellow,
and green more difficult. The MUTCD requires red to be placed
on the left, but there is not 100 percent adherence. Therefore,
when approaching a horizontal signal, colorblind users must use
additional cues-like other drivers and pedestrians-to make
decisions at the intersection.
w w w .i t e.or g

M a rch 2021

33


http://www.ite.org

ITE Journal - March 2021

Table of Contents for the Digital Edition of ITE Journal - March 2021

ITE Journal - March 2021 - 1
ITE Journal - March 2021 - 2
ITE Journal - March 2021 - 3
ITE Journal - March 2021 - 4
ITE Journal - March 2021 - 5
ITE Journal - March 2021 - 6
ITE Journal - March 2021 - 7
ITE Journal - March 2021 - 8
ITE Journal - March 2021 - 9
ITE Journal - March 2021 - 10
ITE Journal - March 2021 - 11
ITE Journal - March 2021 - 12
ITE Journal - March 2021 - 13
ITE Journal - March 2021 - 14
ITE Journal - March 2021 - 15
ITE Journal - March 2021 - 16
ITE Journal - March 2021 - 17
ITE Journal - March 2021 - 18
ITE Journal - March 2021 - 19
ITE Journal - March 2021 - 20
ITE Journal - March 2021 - 21
ITE Journal - March 2021 - 22
ITE Journal - March 2021 - 23
ITE Journal - March 2021 - 24
ITE Journal - March 2021 - 25
ITE Journal - March 2021 - 26
ITE Journal - March 2021 - 27
ITE Journal - March 2021 - 28
ITE Journal - March 2021 - 29
ITE Journal - March 2021 - 30
ITE Journal - March 2021 - 31
ITE Journal - March 2021 - 32
ITE Journal - March 2021 - 33
ITE Journal - March 2021 - 34
ITE Journal - March 2021 - 35
ITE Journal - March 2021 - 36
ITE Journal - March 2021 - 37
ITE Journal - March 2021 - 38
ITE Journal - March 2021 - 39
ITE Journal - March 2021 - 40
ITE Journal - March 2021 - 41
ITE Journal - March 2021 - 42
ITE Journal - March 2021 - 43
ITE Journal - March 2021 - 44
ITE Journal - March 2021 - 45
ITE Journal - March 2021 - 46
ITE Journal - March 2021 - 47
ITE Journal - March 2021 - 48
ITE Journal - March 2021 - 49
ITE Journal - March 2021 - 50
ITE Journal - March 2021 - 51
ITE Journal - March 2021 - 52
https://www.nxtbook.com/ygsreprints/ITE/ite-journal-july-2021
https://www.nxtbook.com/ygsreprints/ITE/ite-journal-june-2021
https://www.nxtbook.com/ygsreprints/ITE/ite-journal-may-2021
https://www.nxtbook.com/ygsreprints/ITE/ite-journal-april-2021
https://www.nxtbook.com/ygsreprints/ITE/ITE_Mar2021
https://www.nxtbook.com/ygsreprints/ITE/ITE_Jan2021
https://www.nxtbook.com/ygsreprints/ITE/ITE_Dec2020
https://www.nxtbook.com/ygsreprints/ITE/ITE_Nov2020
https://www.nxtbook.com/ygsreprints/ITE/ITE_Oct2020
https://www.nxtbook.com/ygsreprints/ITE/ITE_Sept2020
https://www.nxtbook.com/ygsreprints/ITE/ITE_Aug2020
https://www.nxtbook.com/ygsreprints/ITE/ITE_July2020
https://www.nxtbook.com/ygsreprints/ITE/ITE_June2020
https://www.nxtbook.com/ygsreprints/ITE/ITE_May2020
https://www.nxtbook.com/ygsreprints/ITE/ITE_April2020
https://www.nxtbook.com/ygsreprints/ITE/ITE_March2020
https://www.nxtbook.com/ygsreprints/ITE/ITE_February2020
https://www.nxtbook.com/ygsreprints/ITE/ITE_January2020
https://www.nxtbook.com/ygsreprints/ITE/ITE_December2019
https://www.nxtbook.com/ygsreprints/ITE/G110939_ITE_November2019
https://www.nxtbook.com/ygsreprints/ITE/G110110_ITE_October2019
https://www.nxtbook.com/ygsreprints/ITE/G110109_ITE_September2019
https://www.nxtbook.com/ygsreprints/ITE/G108559_ITE_August2019
https://www.nxtbook.com/ygsreprints/ITE/G108250_ITE_July2019
https://www.nxtbook.com/ygsreprints/ITE/G107225_ITE_June2019
https://www.nxtbook.com/ygsreprints/ITE/G104039_ITE_May2019
https://www.nxtbook.com/ygsreprints/ITE/G104038_ITE_April2019
https://www.nxtbook.com/ygsreprints/ITE/G104036_ITE_March2019
https://www.nxtbook.com/ygsreprints/ITE/G103582_ITE_February2019
https://www.nxtbook.com/ygsreprints/ITE/G102868_ITE_January2019
https://www.nxtbook.com/ygsreprints/ITE/G100155_ITE_December2018
https://www.nxtbook.com/ygsreprints/ITE/G100154_ITE_November2018
https://www.nxtbook.com/ygsreprints/ITE/G99495_ITE_October2018
https://www.nxtbook.com/ygsreprints/ITE/G98028_ITE_September2018
https://www.nxtbook.com/ygsreprints/ITE/G97366_ITE_August2018
https://www.nxtbook.com/ygsreprints/ITE/G96287_ITE_July2018
https://www.nxtbook.com/ygsreprints/ITE/G94315_ITE_June2018
https://www.nxtbook.com/ygsreprints/ITE/G93877_ITE_May2018
https://www.nxtbook.com/ygsreprints/ITE/G93065_ITE_Apr2018
https://www.nxtbook.com/ygsreprints/ITE/G91484_ITE_Mar2018
https://www.nxtbook.com/ygsreprints/ITE/G89434_ITE_Feb2018
https://www.nxtbook.com/ygsreprints/ITE/G86608_ITE_Jan2018
https://www.nxtbookmedia.com