It Isn't Your Imagination: Taillights Are a Brighter Shade of Red

If you think they have become brighter - they have and if you think there are a lot more bulbs making up your taillights, you're also right.

All of this is due to an electrical device called a light-emitting diode or LED. You're probably most familiar with them as the power lights on your TV set or CD system at home, or maybe even your dishwasher.

They all work the same way. A small electrical current is applied to a special type of diode whose photos get excited with the right voltage application. In some LEDs, if you apply a voltage one way, it will glow green or yellow and if you apply it in reverse, it will glow red.

The real breakthrough for the car industry came with the high-intensity LED. By changing the chemical composition of the diode slightly (it's called doping), scientists were able to make super-bright LEDs. We're not talking little bitty increases in output, but orders of magnitude such that they could become real safety devices.

It would be nice if the auto industry could claim sole responsibility for this change, but it cannot because it is actually a trickle-down from the traffic light industry.

If you remember traffic lights about 10 or 15 years ago, you probably noticed that they had large green or red lenses that seemed to magnify the lights behind the lens. You were right if you noticed them because that is exactly what they did.

This change, in itself, helped the traffic light designers created some very interesting traffic control signals that could be seen by single lanes, rather than a whole intersection so that if one lane had a green light, the rest of the intersection could remain on red. Of course, the drawback with this type of lighting was that unless you were looking directly at the traffic light - at the right angle - then it was tough to see in bright light.

Enter the LED design teams. Experimenting with different doping materials, they were able to increase the yield of yellow and green LEDs at the start. White and red LEDs were apparently trickier and required more testing.

Apparently concentrating on the red LED segment, the design teams were able to finally make the breakthrough they needed by changing the characteristics of the diodes themselves and they became super-bright. They were not visible not only at night, but also in the daytime, which was one of their original criticisms that they washed out during the day, making them practically invisible. So, now they had the tools they needed to create LED-driven traffic lights.

You've no doubt seen them at intersections around. They are the ones that are very bright under all light conditions and they look like they are made up of a lot of little flashlight bulbs. Well, they are not bulbs, they are really LEDs and they do make a difference (not that people who run red lights really care, they still keep running them). But, for those honest folks who stop at red lights ultra-brights are real visual aides, especially during lousy weather.

Now, let's fast forward to about four years ago in the car industry. Starting at the high end - as they usually do - auto designers began to incorporate bright red LEDs into their brake light designs and turn signals, as well. They automatically became part of the emergency flashers.

That's why when you look at a vehicle such as the Caddy CTS from 2004 you notice a bright red LED display, instead of the more standard bulbs. Indeed, they did put the bulbs to shame, as they were much brighter and more noticeable.

It wasn't that the auto industry wasn't trying to improve its safety lighting because it was. They first took care of front-end lighting with the addition of halogen headlights and very bright reflectors. The halogen tubes were separate from the reflectors and required special legislation to make them legal.

The drawback with this type of headlight is sealing. In wet weather, if the weather seal is compromise, it's easy for the lens to fog up and become a lot less useful. That's why you'll find today's front end lighting is actually designed right into the fender design itself. This way it can be shielded and fared correctly to keep the water out.

Next, the industry knew it had a problem with rear lighting. It had thought that the problem was solved in the late 1980s when the third stoplights were added high in the rear window. Insurance Institute for Highway Safety tests at the time showed dramatic changes in rear-end collisions with just the addition of a third high-mounted rear light.

And, it worked in cars at the time, too. When they were added about 1987, high-mounted rear brake lights cut accident rates drastically. However, those rates began to level off about a decade later, probably, some have speculated, because Baby Boomer eyesight was beginning to shift and making it harder to see standard red bulbs at night (it does happen as a natural part of aging).

Looking around, auto industry design teams first tried to use bright multi-mirrored interior lenses for the rear standard brake lights and they did help, but, they were still not as effective as they could be.

Enter the ultra-bright red LED that the auto industry found that traffic light designers had figured out. Just by swapping out the rear taillight assembly and inserting the ultra-brights, car designers and safety experts saw that people could now see brake lights and turn signals again. It was quite a change.

This wasn't an inexpensive change, either because who rear lighting enclosures had to be redesigned to accept the multiple LEDs that were needed to make the system work. Suddenly you had 20 or 30 LEDs firing at the same time - actually not hard to do if they are hooked up right - but they were in a limited space that had to look good. And, in some instances they actually had to strobe from right to left or left to right to indicate the turn more brightly, if you were turning, or they just all had to come on at the same time to show you were stopping.

For the auto industry, the ultra-bright LED taillight is a mixed blessing. Yes, it was expensive to design around, but, on the other hand, the average lifespan of any LED is somewhere around a lifetime or longer. All they actually are is a piece of doped silicon that is excited by a voltage that is applied to one of the legs with the correct voltage drop.

The nice thing about this is that you can actually cut down on the power requirements of the rear lights because each LED only sinks between .7 and 1.25 volts to make them work, as opposed to the old-fashioned 13-volt light bulb that had a limited lifetime and required more voltage to run.

The last area to see the change to ultra-brights is the front end of top-end cars such as the Bentley or the Audi line. You'll see a line of about 14 or 15 ultra-bright whites outlining the headlight assembly. These lights make these vehicles far more visible at dusk or in heavy weather. They should start to trickle down through the industry in the next few years especially as designers hit the wall with the amount of voltage available from hybrid or all-electric systems. These LEDs will sure help out because of their lower electrical requirements.

So, the next time you think you're seeing things when the car ahead of you hits its brakes, you are not, you are seeing a brighter shade of red.