(ok, I know this resembles the "speed varifier" idea, posted by [stinkycheese], but I had this idea before I read it, so it was not inspired by that idea, and this is more practical)

Basically, this idea entails (no pun intended) tail lights that change colors depending on your speed. For instance, if you're travelling between 1-10 mph (or kph) the tail lights will be red. If you're travelling 11-20, they're orange; 21-30, they're yellow; 31-40, they're green; 41-50, they're deep blue; 51-60, light blue, etc...

This would help solve the problem of accidents caused by low visibility, such as heavy rain or fog. You see the lights in front of you, match your speed to the color, so if the driver in front of you hits the brakes (which would be a different color) you have a good idea of how hard you need to brake yourself to avoid hitting the driver in front of you. This could be combined with the 'Rate-of-Deceleration Lights" for optimum results.
-- 21 Quest, Mar 06 2006

The Aforementioned Idea http://www.halfbake...ea/speed_20varifier
A pedant's worst nightmaire [hidden truths, Mar 06 2006]

The way I drive, you're looking at my ultraviolet tail lights shooting past you.
-- normzone, Mar 06 2006


I fail to see how this is more practical than the idea you mention. It also would be useless and possibly dangerous to the colourblind.
-- hidden truths, Mar 06 2006


Well for one thing, a digital speed display is not visible unless you happen to be close, or if it was it would be comically large. Another reason this is more practical is that a simple numerical display would simply appear as a huge glare in fog or rain.

Colored tail lights mean that that glare (which can be quite visible but is often mistaken for brake lights, which in many cars are the same color, just different brightness) amplifies the effect, making your speed that much more easily determined in low-visiblity conditions.

Another benefit of this is that police can more easily determine how fast you are going. If his speed gun is programmed to take a photograph of anything that crosses its path at a certain speed, the photograph of your ultraviolet taillights makes denial (or claiming gun malfunction) pointless.
-- 21 Quest, Mar 06 2006


X rays.
-- normzone, Mar 06 2006


perhaps just a single blueish (or other unassociated color) light on the back that glows when you touch the accelerater would be less radical. (in other words, it would be triggered the same way as the brake light, when you push down the pedal)
-- gizmosteve, Mar 06 2006


Hmm... that could work, too gizmo.
-- 21 Quest, Mar 07 2006


Many public buses have this sort of light. When the driver is accelerating or going at a constant speed no lights are on. When the driver takes his foot off the gas pedal there is a yellow light that goes on. (I can't recall if it is flashing or solid.) When the driver brakes the standard red brake light goes on along with the yellow light. You're able to tell when the driver is slowing down, coasting, or speeding up depending on what you see.
-- rfl717, Oct 21 2008


Cars which are travelling very fast relative to you are already red-shifted or blue-shifted depending on their direction of travel, but not by very much.

As relative speed is more interesting to you (as a driver) than the other cars' absolute speed, a better approach would be for your car to 'colour in' the other cars in various colours by overlaying a rectangle of colour over these cars on your head-up display.
-- hippo, Oct 22 2008



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