ITE Journal - March 2021 - 36

Kentucky Transportation Center

Signal Solutions. Engineers following the MUTCD's primary
guidance that " Each circular signal indication shall emit a single
color " is a good start, and that basic standard can be enhanced with
a few other strategies.1 
Reflective Backplates. One helpful treatment at traffic signals
is the retroreflective backplate-a strip of material placed around
the signal that provides a detailed indication of its location and the
signal indicators. This is one of many examples where improving a
traffic control device for colorblind road users also provides a safety
benefit to all users, as indicated by research showing a 15 percent
reduction in all crashes at urban intersections with this treatment.

Figure 15. Dual red indications in Quebec, Canada.

Conclusion
Kentucky Transportation Center

Approximately 4 to 5 percent of all road users navigate the transportation system with color vision deficiency. As an industry,
the needs of the colorblind have largely been ignored or not
acknowledged, using color as a single indicator of important traffic
control information. There are numerous ways to make the system
more accessible for colorblind travelers. By doing so, we can make
transportation safer and more efficient for all users. itej

References
Figure 13. Signalized intersection with reflective backplates.

Kentucky Transportation Center

Dual Red Lights. The application depicted in Figure 13 in
Kentucky, USA creates a " Red T " at the top of the signal head.
Its main purpose is to double the visibility of the red light, and it
provides a backup in the case of a burned-out LED or other failure.
For colorblind drivers, it provides additional clarity that it is-in
fact-the red indication.

Figure 14. Dual red light signal indications.
In Quebec, the signal has two red indications, one on each side.
All other indications (green and yellow balls, and any arrows) have
a single indication. This could introduce some confusion regarding
the yellow and green phases, as users might not know where to
expect each to show up.
36

Ma rch 2021

ite j o u rn al

1.	 Federal Highway Administration. Manual on Uniform Traffic Control
Devices with Revisions 1 and 2, May 2012. https://mutcd.fhwa.dot.gov/
kno_2009r1r2.htm (Accessed January 27, 2021).
2.	 Seattle Department of Transportation, Tow-Away Zones https://www.
seattle.gov/transportation/projects-and-programs/programs/parkingprogram/parking-regulations/tow-away-zones (Accessed January 27,
2021).
3.	 Ian Hamilton via Twitter. https://twitter.com/ianhamilton_ (Accessed
June 21, 2020).
4.	 Purcell, Brian. Brian's Guide to Getting around Germany. http://
www.gettingaroundgermany.info/zeichen2.shtml#mark (Accessed
January 27, 2021).

Brian Chandler, PE, PTOE, RSP2IB (M) is the national
director for Transportation Safety at DKS Associates in
Seattle, WA, USA. He serves nationally on the ITE
Transportation Safety Council Executive Committee
and locally on the ITE Washington Section Safety
Committee. Brian's original Grey Means Go article series provides
additional details and more examples. It can be accessed at www.
linkedin.com/in/brianchandler.


http://www.cmfclearinghouse.org/study_detail.cfm?stid=85 http://www.cmfclearinghouse.org/study_detail.cfm?stid=85 https://mutcd.fhwa.dot.gov/kno_2009r1r2.htm https://mutcd.fhwa.dot.gov/kno_2009r1r2.htm https://www.seattle.gov/transportation/projects-and-programs/programs/parking-program/parking-regulations/tow-away-zones https://www.seattle.gov/transportation/projects-and-programs/programs/parking-program/parking-regulations/tow-away-zones https://www.seattle.gov/transportation/projects-and-programs/programs/parking-program/parking-regulations/tow-away-zones https://www.twitter.com/ianhamilton_ http://www.gettingaroundgermany.info/zeichen2.shtml#mark http://www.gettingaroundgermany.info/zeichen2.shtml#mark https://www.linkedin.com/in/brianchandler https://www.linkedin.com/in/brianchandler

ITE Journal - March 2021

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

ITE Journal - March 2021 - 1
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