FHWA-SA-21-039
Backplates with
Retroreflective Borders
Backplates added to a traffic signal head improve the visibility of the illuminated face of the signal by introducing a controlled-contrast background. The improved visibility of a signal head with a backplate is made even more conspicuous by framing it with a 1- to 3-inch yellow retroreflective border. Signal heads that have backplates equipped with retroreflective borders are more visible and conspicuous in both daytime and nighttime conditions.
This treatment is recognized as a
human factors enhancement of
traffic signal visibility, conspicuity,
and orientation for both older
and color vision deficient drivers.
This countermeasure is also
advantageous during periods of
power outages when the signals
would otherwise be dark, providing a
visible cue for motorists to stop at the
intersection ahead.
Considerations
Transportation agencies should
consider backplates with
retroreflective borders as part
of their efforts to systematically
improve safety performance at
signalized intersections. Adding a
retroreflective border to an existing
signal backplate is a very low-cost
safety treatment. This can be done
by either adding retroreflective
tape to an existing backplate or
purchasing a new backplate with
a retroreflective border already
incorporated. The most efficient
means of implementing this proven
safety countermeasure is to adopt
it as a standard treatment for
signalized intersections across a
jurisdiction or State.
Implementation challenges
include minimizing installation time,
accessing existing signal heads, and
structural limitations due to added
wind load in instances where an
entire backplate is added. Agencies
should consider the design of the
existing signal support structure to
determine if the design is sufficient to
support the added wind load.
15%
reduction in total crashes.1
Safety Benefits:
Retroreflective Border
Signal Backplate
Signal backplate framed with a
retroreflective border. Source: FHWA
Retroreflective borders are highly
visible during the night. Source: South
Carolina DOT
1 (CMF ID: 1410) Sayed, T., Leur, P., and Pump, J., “Safety Impact of Increased Traffic Signal Backboards Conspicuity.” 2005 TRB 84th Annual Meeting: Compendium of Papers CD-ROM, Vol. TRB#05-16, Washington, D.C., (2005).
OFFICE OF SAFETY
Proven Safety
Countermeasures
For more information on this
and other FHWA Proven Safety
Countermeasures, please visit
https://highways.dot.gov/
safety/proven-safety-counter
measures and https://rosap.
ntl.bts.gov/view/dot/42807.
Attachment 7