Many car safety ideas aim to increase safety by limitation of speed or cessation of movement. The net result is a more boring drive. I don't care what anyone says, speed is fun and I like driving fast.

Before I get hit with the "MFD Rant" tag, I should explain how this relates to the idea. I like driving fast, but I also like driving safely. I don't want to injure myself or anybody else. I believe measures that promote safety by raising driver awareness can do more to increase road safety than restrictions that prevent speeding and the idea is posited with this in mind.

Conventional vehicle brake lights convey only one piece of information when lit: the vehicle's brakes have been applied. Other vehicles cannot tell how rapidly the vehicle is decelerating. If a vehicle is decelerating without brakes applied, there's no indication of this either. There's no indication of acceleration at all.

Speed lights will replace the brake lights and will take the form of six chevrons, three pointed upwards to indicate acceleration and three inverted to indicate deceleration. As well as being differently orientated, the two sets of chevrons will be differently coloured to eliminate the possibility of confusion. An accelerometer measures the rate of acceleration/deceleration of the vehicle. At maximum acceleration, all three accelerator chevrons are lit. With a little less acceleration, two are lit, and when the vehicle is accelerating slowly a single chevron is lit. Similarly when a vehicle is decelerating rapidly all three decelerator chevrons are lit, with moderate deceleration two chevrons are lit and when a vehicle is decelerating gently, a single chevron is lit. Within a given tolerance, no chevrons are lit, indicating that the vehicle's speed is relatively constant.

This system would give valuable advance warning of changes in speed and would be particularly useful in low light conditions when judging distances can be tricky.
-- DocBrown, Nov 25 2005

Smarter Tail Lights for Cars http://novaspivack....marter_tail_li.html
Interesting plug on this idea [skinflaps, Nov 25 2005]

Interesting, although conjures up an image of mass confusion in heavy traffic.[+]
-- skinflaps, Nov 25 2005


I don't think so [skin]. Same as normal, you see a red light, you slow down. You see a...[thinks]...green light, you know the car in front's speeding up. All this does is tell you how heavily to apply the brake if you need to. Could help to reduce panic braking and shunting in crowded conditions, amongst other benefits.
-- DocBrown, Nov 25 2005


Doc: have you checked through Car: Brake Lights to see if this is already halfbaked?
-- st3f, Nov 25 2005


Hey [st3f], I normally check before posting but didn't this time. Just had a look - a few people have done deceleration lights or variable intensity brake lights, but so far as I can see, no one's done this before (both acceleration and deceleration, non-reliant on light intensity).
-- DocBrown, Nov 25 2005


This is a good idea. Graduated accel/decel instead of going/braking. Most drivers already understand the idea of 'more lights means more power'. I would guess the accel lights are green and the decel lights are red?
-- sleeka, Nov 25 2005


That seems the sensible default [sleeka]. I'm sure if this was introduced you'd see the boy racers replacing their acceleration lights with blue chevrons, and probably adding 4th and 5th acceleration chevrons, to indicate that their souped-up crapmobiles are only just sub-sonic. Gotta love those guys!
-- DocBrown, Nov 25 2005


Hey, you don't know how much restraint it took me to not suggest a 4th 'up' chevron for faster vehicles. I actually typed it, but then erased it, fearing the fact that I may be viewed as a youthful speed demon with a fast car.
-- sleeka, Nov 25 2005


Nothing wrong with being a youthful speed demon, so long as this state is tempered by a proper respect and concern for the safety of others. I speak as a youthful speed demon with a slow car.
-- DocBrown, Nov 25 2005


How about a variable screeching tyre sound, louder for more deceleration?

//I like driving fast, but I also like driving safely// But is the feeling of 'fast' relative to the feeling of 'unsafeness'?
-- Ling, Nov 25 2005


//But is the feeling of 'fast' relative to the feeling of 'unsafeness'?//
I suppose it can be [Ling] but that's not such a bad thing in my car, which is old and slow. A speed that would feel boring in a more modern car feels quite exhilirating in mine.
-- DocBrown, Nov 25 2005


A red light represents a point one must not proceed through, whether the light is on a vehicle or a traffic signal. A green light on a traffic signal is a point through which one may proceed.

If a vehicle is accellerating, the chevrons would seem to invite an overtaking vehicle to proceed through it.
-- supercat, Nov 25 2005


I think most people are discerning enough to recognise the distinction between a traffic light and another vehicle. Furthermore, I think those incapable of this simple act make a compelling argument for their removal from the road. I don't see anything wrong with interpreting green as "go" and red as "stop", but if it bothers you [supercat], we could standardise on another colour for the accelerator chevrons. I thought I'd steer clear of blue because of its association with the emergency services. Green/red was a nice contrast but take your pick!
-- DocBrown, Nov 25 2005


Fair enough, Doc. I thought I'd check as there are a load of ideas there. Feel free to dump my anno~s overboard.
-- st3f, Nov 25 2005


I knew what you'd come up with before the third paragraph :) +
-- DesertFox, Nov 25 2005


I've thought of this before, seems like a good idea. I would go with 4 or 5 chevrons though, for more precision. Hell, maybe we can have a digital speedometer on the rear bumper.
-- Bukkakinator, Jun 03 2008


...but what the brake-light is telling you is basically the differential of speed (i.e. a=dv/dt) - I'd suggest that the differential of this (i.e. the rate of change of accelaration, or da/dt) would be useful too. In fact, why not a whole line of brake-lights, each showing successive differentials?
-- hippo, Jun 03 2008


//(i.e. the rate of change of accelaration, or da/dt) //

Also known as jerk, jolt, surge, or lurch. +
-- csea, Jun 03 2008


Hey [lurch], [csea]'s calling you a jerk.
-- coprocephalous, Jun 03 2008


//(i.e. the rate of change of accelaration, or da/dt) would be useful too//

[Hippo] You've got one helluva car if your rate of acceleration is increasing at any meaningful value.

The only time those things would light up is in the negative ... during a wreck.
-- MikeD, Jun 04 2008



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