Is there any existing research which shows that yellow tail lights are safer than red tail lights for bicyclists? there's a bill proposed in the nys legislature to allow yellow as an option in our state, and we're trying to respond based on the 'state of the art.' my view has been that if bicycles are to be treated as vehicles, then they should have the same color lighting as vehicles (red); on the other hand, since yellow is more visible under certain conditions, it may be a safety benefit to use this color as an option. I look forward to your response.
Writer and expert consultant on bicycling; Certified Effective Cycling Instructor; Technical writing, translation (German->English, French->English); Mechanical design, acoustics and music.
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I doubt there is any research which has addressed this specific question. Dunlap Associates did some research a few years back comparing various types of conspicuity equipment, but I don't think that this research did a direct comparison of two taillamps identical but for the color. (John Forester has examined the Dunlap research paper and may have insights as to its relevance to this question.)
The central issue in the red vs. yellow (or amber) debate in years past has been brightness. With reflectors, this is a significant issue, since a red reflector of the same size sends back less of the incident light than an amber one does. I think that it does make sense to permit amber rear reflectors, for this reason. Like many bicyclists, I use a large SAE (automotive) amber reflector on the rear of my bicycles. I like the ones shaped like rectangles with rounded ends, which fit nicely within the width of a road-bike rear fender.
With taillamps, color is of less concern than with reflectors as it affects brightness, because even a red taillamp does not have to draw very much power to be of sufficient brightness. I tested a Panasonic generator taillamp about ten years ago when consulting in an accident lawsuit, and it was bright enough, with its 0.5 watts of electrical input, to be seen at distances up to 800 feet with oncoming car headlamps in the next lane. It was, to be sure, one of the best-designed taillamps on the market at that time. For my own battery lighting systems, I use a 2.4 watt generator headlamp bulb in a less optically efficient Union taillamp (the smaller Union taillamp, about 3 cm in diameter), and it is plenty bright. It also gets me in compliance with the law, at least in Massachusetts, since I must by law have a red rear reflector *or* taillamp, and may by our law use additional equipment not specified. (Doug Mink has posted the Mass.law and links to the laws of a number of other states on the massbike web site, in case you want to look them up).
Today's LED technology makes taillamps many times as efficient, and red LED's are the most efficient LED's. For this reason too, I think that the central issue in taillamp standards these days ought to be to standardize adequate brightness, while the central issue in rear-facing conspicuity equipment of any kind is to jettison the CPSC three-panel rear reflector design for something brighter in the direction cars actually come from, and the central issue in nighttime conspicuity is to get the great, uninformed majority of bicyclists to use adequate equipment, overturning the Federal regulation which fools them into thinking that's what they got when they bought their bikes equipped with ten reflectors and no lamps. In this context, legislation to make yellow taillamps legal could be a diversion and accomplish more harm than good, unless its main accomplishment is also to get amber rear reflectors legal, and even that accomplishment is hardly the one we really need.
Many taillamps, and particularly U.S.-made LED lamps, are not nearly as bright as the Panasonic which I tested and, I am quite sure, do not comply with the ISO standards which the late Fred DeLong worked so hard to establish. This is a particularly American phenomenon and is bound up with the U.S. Consumer Product Safety Commission's failure to set standards for bicycle lamps or to adopt the ISO standards. An American bicycle lighting standard may be on the way with the ASTM standards which are under development, though the the CPSC is still infatuated with the all-reflector system.
You will notice that most of the lamps coming in from overseas do comply with ISO standards, and carry the ISO seal of approval on their lenses. (And this means that we are unlikely to see foreign-made taillamps in amber, even if we make that legal. For that matter, we're unlikely to see domestic taillamps in amber just because one state makes that legal.)
There's another, perplexing side to this issue: yellow LED's are being used for front lamps. Should they be legal? If they are, then we won't be able to tell as easily whether bicyclists are coming or going. Here is an e-mail exchange I had recently on the topic of yellow LED headlamps:
***
At 13:25 11/25/96 EST, Schimek, Paul M. (Schimek@volpe2.dot.gov) wrote:
>Do front LED flashing lights perform adequately for urban night riding as a
>sole head light? Do they conform to state laws?
In theory, an LED lamp could have adequate brightness, but the commercial ones I have seen aren't very bright. I think that the manufacturers overstress the long battery life feature at the expense of brightness.
One problem is that a typical (cylindrical, dome-topped, small) LED has its own, built-in directivity pattern, which tends to be quite sharp. One way around this problem is to fan out several LED's so they cover a range of angles.
Another problem is that it becomes increasingly difficult to make LED's as the wavelength decreases. That's a quantum physics problem -- shorter-wavelength photons are more energetic and are generated by larger transitions in the orbits of electrons in the dopant of the diode's semiconductor material, requiring the use of some rather rare chemical elements. Blue LED's are now available, but they are expensive, and, I think, not as efficient as the green or, especially, red ones.
For this reason, current LED bicycle headlamps produce yellow light rather than white light -- yellow light is easy to produce by combining red and green. Some LED's produce both red and green -- one input polarity produces red, the other green, and alternating polarity produces yellow through additive color mixing and persistence of vision.
In France, bicycle headlamps are (or were, last time I was there, in 1989) *required* to be yellow (why? probably so you can tell it's a bicycle approaching, but I don't know -- in any case, this requirement is dumb because it dims an incandescent lamp). In most other countries, a sole front headlamp is required to be white, and so a yellow LED lamp does not comply with the law. I don't see any convincing reason to prohibit a yellow LED lamp as a sole front headlamp, as long as it's bright enough -- with LED's, the tradeoff between brightness and color is the inverse of the one when filtering an incandescent lamp. Remember that submariners wear red goggles to adapt their night vision -- a bright, yellow, orange or red lamp could illuminate the roadway while impairing night vision less than a white lamp.
A lamp does not comply with the law, and is useless for illumination, if it flashes. Granted, the flashing of LED's is less annoying than that of strobe lamps -- the LED's are actually on for a considerable part of the cycle, so you can actually determine the position of a flashing LED lamp ahead of you. But on the other hand, LED lamps do not have to flash -- some Vistalite models have the option of turning off the flashing, and Dave Wittenberg, who commutes locally, has built a powerful (and very efficient) non-flashing red LED taillamp. Many of the rear-window brake lamps on cars are strings of LED lamps now, and they don't flash either. You can identify them by the deep, pure crimson color which makes filtered incandescent red lamps look orange by comparison.
LED's are a technology still under development, and considerable improvements can be expected. Within ten years or so, it should be possible to have the LED equivalent of a present 10-watt halogen hedalamp, but which draws only 1 watt. That will be a major improvement.
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I would stop and drag my feet before endorsing the concept of yellow taillights wholesale. Reason: familiarity breeds recognition. If every vehicle's taillights are red, and bright enough to be seen, then we have a better idea what they are.
I realize that the driving environment is chock-full of exceptions to this consistency concept, but that doesn't mean that we should stop trying to keep the visual cues of the driving environment consistent.
I also wonder aloud whether brightness and detectability are the big issues or not. Sure, at some point they were, but we can sometimes become like generals fighting the last war, forgetting that there are bigger questions at stake. My point here is that if the red lights can be shown to be bright enough already, then the disadvantages of switching to yellow taillights loom larger.
Statistically, we know some people get struck from behind despite having today's red taillights. Is it because the taillights aren't bright enough?
It might not be. It might be that if we were to look at these accidents systematically, we'd find other causes were dominant (driver is in la-la land, driver is drunk, high beams blinded the driver, very lousy sight distances around a sharp curve, etc.).
Blomberg's research from 1986 showed the best detection distances came from leg lights and Belt Beacons, both of which were dim, dim, dim. So under his test conditions, brightness wasn't necessary for detection.
That said, I kind of like the idea of a bike having a steady red taillight for recognition ***and*** a flashing yellow LED light taillight for detection. This also bears some resemblence to a slow motor vehicle using its four-way flashers.
As for ASTM and lighting, lighting is on ASTM's back burner. Maybe some work will begin next year. It's not the top priority of the attendees.
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A couple of thoughts regarding yellow tail lights. Red sends a clear unmistakable message to motorists that they are coming up on the back of an object, where yellow is reserved for side and turn signals....so some confusion can result.
Yellow is the best color for detection, because it is in the middle of the color spectrum, so most people have no difficulty seeing it.......it works for longer distances, and for all ages, etc. I would suggest that your law not be changed to replace red, but to suggest that yellow can be used to enhance a red tail light or red reflector....especially a blinking yellow light.
Editor, The Bicycle News Agency, Dansk Cyklist Forbund, Roemersgade 7, 1362 Copenhagen K, Denmark. Phone: +45 - 33 32 31 21 web site: http://webhotel.uni-c.dk/dcf
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I read a bit about the yellow rear lights, and just wanted to tell you, that it's very likely that the Danish Authorities will allow blinking red rear-lights for cyclists from some time next year. Previously blinking lights have been reserved for emergency vehicles and extrodinary slow vihicles (trucks with wide or heavy loads or maintenance vehicles).
But as we got a law a couple of years ago which made lights on automobiles mandatory 24 hours a day, it is as if cyclists need more "power" to make them visible. Anyway - allthough I am not a great fan of this "ocean of lights" I must admit I feel safer with a blinking red (rear) light.
Member: Mid-Hudson Bicycle Club, League of American Wheelmen, Adventure Cycling, 14 Sherwood Place, Hyde Park, NY 12538, 914 229-6551
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We ask to be allowed to use yellow tail lights. The bill has been introduced in the NYS Senate as S00623. The legislature has previously passed law, but it will be reintroduced.
The misunderstood component of this discussion is color blindness. Based on a study done during WWII, approximately 10 percent of all males have some degree of diminished red vision. Red blindness. What does red blindness do?
These men do not see red as a bright or warning color. A few have never seen the color as anything other than black or dark brown. Like all human beings, they adapt to their disability, and since they adapted so early in life, most are not aware they have diminished red vision. They stop for green lights where the bulb has burned out. They leave more room between their car and the one in front. They turn on red arrows. And on rare instances, they run the invisible red lights.
Since the demise of the authoritarian SAE (Society of Automotive Engineers), color specifications for traffic lights appear to have been lost. NYS DOT mounts red traffic signals that even I cannot see with my car parked in front of them. (I had been driving through a red turn arrow for months when a friend noticed, told me about the arrow and I figured out the combination of lights that allow me to legally make the turn. This light probably met a DOT specification.)
Bicycles at night without lights are dangerous. For ten percent of the male population, specifying a red light is equivalent to specifying no lights at all, whether or not the light flashes (ala Denmark).
Some know red is a poor color: New York State DOT paints their trucks bright yellow for visibility to others, not red. Their workers wear bright orange for visibility to others, not red. NYS requires hunters to wear bright orange for visibility to others, not red. The insurance industry asks fire department to paint their equipment lime-green or yellow for visibility to others, not red. Even NYS DOT has begun using laser-like strobes in some traffic lights for visibility. (The strobes are super.)
Should bicyclists ask for less visibility?
Twenty years from now, the public will understand the wisdom. Automobile seat belts and bicycle helmets took decades for public acceptance. We must embrace a long educational process. That process begins with New York State permission to use yellow tail lights.
I urge your support of the yellow tail light legislation for bicyclists.
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