Transportation -
Flashing Lights - Do They Really Slow
Traffic?
Flashing beacons (commonly called flashers or flashing lights) are frequently requested by
communities in the belief that they will reduce vehicle speeds. Unfortunately, this is not
necessarily the case. The following discussion of flashing beacons is offered in the
interest of broader public understanding of what flashers can do and what factors must be
considered before they should be installed.
Contact Transportation at 480-644-2160
for a Flashing Lights brochure.
A flasher is generally installed at an intersection or in conjunction with a warning sign
in advance of an area requiring greater than normal care by the average driver. Flashing
beacons serve a useful purpose where the flashing yellow is used to alert drivers to unusual
conditions that are not readily apparent, such as: obstructions in the roadway,
uncommon roadway conditions, narrow bridges, or unusual conditions hidden from the
motorists' view. One of the more common locations where a flasher can be used effectively is at a
signalized intersection located just beyond a vertical or a horizontal curve, when the
intersection is hidden from the view of approaching motorists.For any flasher to be effective, it must command the respect of the motoring public.
In other words, immediately after seeing a flasher, the driver must consistently
see an unusual condition which is being singled out for attention. Furthermore, the
condition that the motorist sees must be viewed by the motorist as serious enough
to justify his having been alerted.
When flashers are used improperly and installed at locations where they are not warranted,
they soon lose much of their effectiveness. They simply cease to command the respect of
the drivers. What happens is that after continually being alerted to a condition which
seldom, if ever, appears to be truly unusual, drivers actually stop "seeing" the
flasher. When this happens, flashers which are truly needed may well be disregarded by
drivers who have become conditioned to believe that flashers are just "window
dressing." Because of this normal human reaction, even one improper use greatly
reduces the effectiveness of essential flashers.
Quite often, community requests for flashers are emotional responses to symptoms, rather
than attempts to solve underlying problems. To put this into perspective, let's use an
appropriate analogy: the case of measles. Obviously, to cure a patient who has measles,
the disease itself (measles) must be treated not the symptom (rash). In traffic control,
it is not uncommon for public responses to be directed at treating symptoms. For example,
in cases where concerned parents are requesting flashers on pedestrian warning signs, a
traffic investigation all too frequently reveals that:
- There is no "safe route to school" plan in the community.
- There is no pedestrian safety program in the schools.
- Very young children are allowed to wander to school by whatever route their youthful
minds prefer.
- Parents are willing to abdicate their responsibilities by placing the entire burden for
pedestrian safety on a traffic control device.
- Local law enforcement officials turn a blind eye to youthful pedestrian traffic
violations.
Where traffic laws are enforced by conscientious law enforcement officials, outraged
parents explain away the irresponsible behavior of their children by claiming that the
fault lies in inadequate traffic control devices, not in their children.
Flashers that are installed when these conditions exist result in the following:
- The flasher soon becomes part of the normal driving environment and is ignored.
- Parents continue to ignore their responsibilities to their children.
- The community continues to avoid treating the real problem.
- Other flashers, which are justified, are frequently disregarded by motorists conditioned
to believe that flashers can be safely disregarded.
In summary, when flashers are properly located, they serve a useful function. When they
are used improperly and installed in locations where they are not warranted, they soon
lose much, if not all, of their effectiveness. More seriously, improper use greatly
reduces the effectiveness of other flashers installed in areas where there is a real need.
Above all, it is essential to prove that there is a problem which can be solved through
the installation of a flasher before actually employing one. Too often, flashers are
installed when someone assumes there is, or is going to be, a problem. It is of the utmost
importance that flasher installation be held to a minimum in order to maintain a high
degree of respect for the flasher installations that are truly needed.
This discussion was written by the Arizona Department of Transportation with the express
intent that it be distributed freely.
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