Hi all,

Bob Sutterfield wrote:

>>>Can anyone point me to studies of safety comparing blinking with
solid
bicycle lighting?<<

You got several excellent replies, but I have a study to add.
(Executive summary: The study supports Michael Poplawski's comments
that a flashing light is easily detected but not good for determining
position.)

My favoreite study on this subject is:

Blomberg, Richard D.; Hale, Allen; Preusser, David F., Experimental
Evaluation of Alternative Conspicuity-Enhancement Techniques for
Pedestrians and Bicyclists, Journal of Safety Research, Vol. 17, pp
1-12, 1986, copyright 1986 National Safety Council and Pergamon Press
Ltd.

In this study, the researchers used an 8.5-mile closed-course road
system on a military base and measured motorists' detection and
recognition distances from barricades, Belt Beacons (the non-LED
flashing light of the 1970s, which flashed at 40 to 90 x per minute,
depending on which model you bought), leg lights, a fanny bumper,
reflective dangle tags, a dark pedestrian for a baseline, and some
other conspicuity treatments for pedestrians, bicyclists, and fixed
objects. The Belt Beacon was compared with the fixed object items.

Despite the Belt Beacon's dim and infrequent flashes, it cold-cocked
other gizmos for detection distance: 1,341 feet, compared with 473
feet for traffic cones, 1,201 feet for the strobe light, 1,039 feet for
the reflective arrow, 1119 for a barricade.

But the Belt Beacon stunk on recognition distance: 24 feet, versus 617
for the aforementioned barricade.

The leg light was superior: 1,303 feet detection distance and 481 feet
recognition distance.

Of course, on the rare occasions when the government funds a good study
like this, it takes heaps of time and money (which is why we look at
21-year-old studies) and there are dozens of permutations we wish they
would have tried.

My opinion is that a blinking LED light, either red or yellow, combined
with a steady red light and reflector, would be a rear-facing treatment
that would test well for detection, recognition, and ability to locate.
(The more points of light, the easier to locate.) The LED light is
usually more convenient than the leg light, and I doubt leg lights will
ever make a comeback, even though I like them myself.

I think the comparison with strobe lights in discos is somewhat
irrelevant because LED lights are too dim and too far away to be as
distracting as disco strobes. I also repeat my preference for
combinging the blinking light with a steady light.

When riding a paceline at night, it is common courtesy to have no
flashing lights. LED flashing lights _are_ distracting when they are
that close.

On the subject of front lighting, different governments have different
requirements. Pennsylvania law specifically requires a light that is
designed to illuminate the road surface. Washington DC law
specifically allows leg lights, which do not illuminate the road
surface.

A front light's main job is to alert others to the bicyclist's
presence. This is important because about 3/4 of all night car/bike
collisions involve a car coming from the bicyclist's front. While I'm
mindful of the drawbacks of front strobes, I suspect front strobes
would be sufficient to alert the motorist to the bicyclist's presence
in the vast majority of these collision situations. I do not expect
we'll ever see a study that would compare the effectiveness of front
strobes and steady front headlights.

Some state laws specifically allow blinking lights on bicycles. In
general, the products in the marketplace have evolved much faster than
the legislatures have.

John Schubert

P.S. Darrell, you can cite me anytime.



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