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12-18-2004, 02:53 PM

Frank Krygowski wrote:
> > 2. Always use some steady light along with a flashing light, so that
> > the flashing light is perceived as having a coherent position in space.
> > It needn't be a bright steady light, but use something steady.
>
> The tracking of a flashing light can be a problem, but only if the "off"
> portion of the cycle is very long relative to the "on" portion. Most
> LED lights have a fast enough "twinkle" cycle that there is no problem
> tracking their position.
>
> Redundancy is good, but one needn't be paranoid about this. I mentioned
> the other day a study of visibility treatments of cyclists and
> pedestrians. A bike with only CPSC reflectors (no lights) was detected
> by drivers at 844 feet. When a simple, low-power leg lamp was added,
> the bike was detected at 1,300 feet! Even at a closing speed of 40 mph,
> this gives the driver over 20 seconds to react.
>
> Start counting 20 seconds now. You'll see there's no great need for fear.

The condition you have to work for is the one where there are other competing lights,
and the idea is to impress on the driver that he has to do something unusual to
avoid you, like give you lane clearance.

A bike alone on a dark road is okay but not the worst case. In a busy area he's
not seeing you any 20 seconds ahead.
--
Ron Hardin
rhhardin@mindspring.com

On the internet, nobody knows you're a jerk.

12-18-2004, 02:53 PM	#45 (permalink)
Ron Hardin Guest Posts: n/a	Re: OGC Optik7 Flashing LED Warning Frank Krygowski wrote: > > 2. Always use some steady light along with a flashing light, so that > > the flashing light is perceived as having a coherent position in space. > > It needn't be a bright steady light, but use something steady. > > The tracking of a flashing light can be a problem, but only if the "off" > portion of the cycle is very long relative to the "on" portion. Most > LED lights have a fast enough "twinkle" cycle that there is no problem > tracking their position. > > Redundancy is good, but one needn't be paranoid about this. I mentioned > the other day a study of visibility treatments of cyclists and > pedestrians. A bike with only CPSC reflectors (no lights) was detected > by drivers at 844 feet. When a simple, low-power leg lamp was added, > the bike was detected at 1,300 feet! Even at a closing speed of 40 mph, > this gives the driver over 20 seconds to react. > > Start counting 20 seconds now. You'll see there's no great need for fear. The condition you have to work for is the one where there are other competing lights, and the idea is to impress on the driver that he has to do something unusual to avoid you, like give you lane clearance. A bike alone on a dark road is okay but not the worst case. In a busy area he's not seeing you any 20 seconds ahead. -- Ron Hardin rhhardin@mindspring.com On the internet, nobody knows you're a jerk.