Half a croissant, on a plate, with a sign in front of it saying '50c'
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Display Best Speed To Catch Green Light

An LED sign shows you the right speed to go through the next traffic light without stopping.
  (+25, -7)(+25, -7)
(+25, -7)
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Have a digital sign about a half mile or quarter mile from a traffic light showing the driver the right speed to go to make the green light. The speed on the sign change depending on how many seconds the next red light is.

For instance: If the traffic light is red, the sign might tell you to slow down to 30 mph so the light will be green by the time you get up to it. If the traffic light is green, the sign might tell you to go 50 mph to get to the intersection before the light turns red.

The digital sign could have a sensor that sees when the traffic light is green or red and a small computer to time the light to set the speed. This would prevent the need to have wires connect the digital sign to the traffic light.

An added benefit would be to reduce speeders since ignoring the digital sign recommended speed could cause you to have to stop at the traffic light anyway.

Another benefit would be to save energy and gas consumption by having drivers slow down to 30 or 20 mph instead of coming to a complete stop.

hawkins_russ, Jul 30 2007

"Green Wave" system in The Netherlands. http://www.trafficl...a/17/w_04040208.JPG
System already deployed, similar to the proposal. [AllyAl, Aug 04 2007]

[link]






       This is a good idea, but it might be better to have a small display in each vehicle that receives a wireless signal. The signals should be made with information from the computers that control the stop lights. That way it can give you more and better information.
BJS, Jul 30 2007
  

       Welcome to the halfbakery [hawkins_russ], and good idea [+].
acurafan07, Jul 30 2007
  

       ----------------------------- (+)   

       Something like this was implemented in Germany in the 1970ies. Backlit numbers on posts next to large thoroughfares indicated roughly - in 10km/h increments - the speed to use to have traffic lights stay green - the so-called "Green Wave" (Grüne Welle). In the DDR, I read in the German Wikipedia entry on the subject, they had displays near intersections, more as described, in 5km/h increments. The West-German practice was, I'm sad to read, discontinued in most cities because it just didn't do that much (I thought it was really cool, back then); the East-German version was stopped after the reunification to homogenize the traffic systems (sigh). These days, you're more likely to see traffic lights change in reaction to the presence of traffic, not the other way around.
jutta, Jul 30 2007
  

       Roadside sign: "If you can stay within +/-2km/h of 34km/h, not only will you get a green on the next traffic signals but you'll win this toaster too, and have a chance to go for our jackpot draw"
hippo, Jul 30 2007
  

       I also saw a slightly updated version of this in Germany (in Essen I think) in the late 80s / early 90s, which was an LED readout in 1kmh increments. It was very effective, I've often wondered why it never became widespread.
marklar, Jul 30 2007
  

       I have always heard that if you are going exactly the speed limit posted you will get all the green lights. That is provided you got the first one and kept your speed the same.
xandram, Jul 30 2007
  

       Love it, bun it.   

       This saves weeks of observation and calculation and would render even tourists into local driving pros.
elhigh, Jul 30 2007
  

       So what do you do when the idiot in front of you INSISTS on driving two mph slower than the speed needed to get green lights?   

       Sounds like a recipe for road rage.
Galbinus_Caeli, Jul 30 2007
  

       There used to be a series of lights on the way into Manchester from the M6 which were preceeded by the sign: "These lights are timed to go green for drivers travelling at 30mph". And they were. And it worked. Your idea is better, though marginally more complex. [+]
wagster, Jul 30 2007
  

       Further to what Jutta said, well-designed traffic lights should be timed to keep the traffic moving at the legal speed limit. And for on-demand traffic lights (pedestrian crossings, etc.), the light will mostly be green (in theory), so there's not much point in doing this.
DrCurry, Jul 30 2007
  

       Sometimes there will be "no solution", though. E.g. if the light in the distance is green but about to turn red, your sign will display either "250 mph" or "0.1 mph".   

       I guess in these cases the sign just stays blank or says "Stop." (Anyway, make sure that the sign never orders you to break the speed limit.)
phundug, Jul 30 2007
  

       Oh yeah, the system with a camera and timer probably wouldn't work. It would have to be reset for power-outages and in situations where emergency vehicles screw all the light cycles up.   

       //(Anyway, make sure that the sign never orders you to break the speed limit.)// Although I don't know anyone who would mind that.   

       "Sir I pulled you over because you left rubber at the intersection of Abbot and Jenkins and proceeded to go 85 in a 40 zone."   

       "Oh... Sorry officer, but that L.E.D sign back there told me to."   

       (Shakes head) "I knew those damn things were a bad idea from the start. Well, drive safely."   

       (Car drives away, officer later realizes that there is no L.E.D sign at the intersection of Abbot and Jenkins.)
acurafan07, Jul 30 2007
  

       299,792,458 m/s should do it, and it holds for red, blue and most other wavelengths as well.
zen_tom, Jul 30 2007
  

       [Xan] I made that same type of comment to an older idea of mine and was told that it only works in one direction. The lights in the reverse direction and cross streets can't all allow the same speed limit flow to work.   

       I liked UB's take on it with Warp and Weft traffic.   

       Foot down and looking hard.
normzone, Jul 31 2007
  

       There was a SoCal town that did this back in the eighties - a lovely place called Upland. It was laughable. They called it "optimum speed" - it was displayed on signs by the side of the road. Every time I drove by it, I was behind a line of cars going half the displayed speed. This is no exaggeration.
globaltourniquet, Jul 31 2007
  

       On the highway in the Netherlands the best speed is displayed and mandatory. It helps prevent traffic jams. everybody drives faster even though you can get a ticket. People just don't understand the concept that when you drive faster you might become the cause of a traffic jam and get there later. +
zeno, Jul 31 2007
  

       In our town you can drive down our (fairly long) main street, through the town square and at least half a dozen lights if you start at the right time and keep up a steady 37MPH.   

       Unfortunately it's a 30MPH limit:-/   

       By the way I *swear* I've seen those signs somewhere - either UK or mainland Europe. And of course the painted fixed speed ones that came first. It'll come back to me eventually where I saw them.
gtoal, Aug 01 2007
  

       Looks good on paper. Not gonna hold in the rigors of traffic. You're an idealist, you are!
k_sra, Aug 02 2007
  

       "If you hold this speed you will get a green light, but unfortunately there is already a queue, so you'll have to stop anyway."
Ling, Aug 03 2007
  

       Exactly my experience in Upland, [Ling], so, baked, and badly.
globaltourniquet, Aug 03 2007
  

       It's approximately 81.2% baked. See the link for an example similar system. This "green wave" system in use in The Netherlands (maybe also in Belgium) does not dynamically indicate the speed, so does not have all the elements in the idea.   

       This system is new and not widely deployed, even in The Netherlands.
AllyAl, Aug 04 2007
  

       This is an ideal idea for places with a one-way system. On a macro scale it would mean cars travelling in parcels around the system, with the inter-parcel gaps being just the right length for the red lights to allow traffic to cross the main one-way system.
vincevincevince, Aug 06 2007
  

       A variation to this idea would be an in-car display in each car which told the driver "If you continue at your present speed, the next light will be this colour when you reach it", taking into account the phasing of the lights and the distance of the car from the lights. It could be integrated into the satnav.
hippo, Aug 09 2007
  

       c

[EDIT] Oops, [zen_tom] beat me to it.
AbsintheWithoutLeave, Aug 09 2007
  

       I like Hippo's idea, but it doesn't tell you what you should do if the light is going to be red; should you speed up or slow down?
A further modification would be a 360 degrees gauge with alternate red and green quadrants. You would need to know if slowing down or speeding up a fraction would suffice. This would be shown by a needle pointing to one side of a red quadrant. To drive the pointer clockwise would require faster driving, and... well, I think that's enough said.
Ling, Aug 09 2007
  

       Ling, does your home planet not use yellow lights? it sounds as if hawkin's home doesn't either. I have learned to gauge the time between yellow to red by using a little mantra "I can stop, I can still stop, now I can't" which I taught my teens to use at intersections.   

       I know it's lame but it works for me.
dentworth, Aug 09 2007
  

       [dentworth], here at Ling'sVille, the duration of the amber light is worthy of a thin line dividing red and green.
Ling, Aug 09 2007
  

       How about a carrying around a bucket of Bose-Einstein condensate to slow down the light?
AbsintheWithoutLeave, Aug 09 2007
  

       //I have learned to gauge the time between yellow to red by using a little mantra "I can stop, I can still stop, now I can't" which I taught my teens to use at intersections.//   

       i have one, too: "i can make it if i floor it!" = )
k_sra, Aug 09 2007
  

       I confess to using that one too.
dentworth, Aug 09 2007
  
      
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