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Replace "light" with "sausages" and this may work...

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Illuminated Crossing

Intensely flood the crossing area of a road with bright colour (easily visible even in bright sunlight)
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One of the problems with having a little green man walking, and a little red man legs akimbo, on a thin black post, all the way across the road, is that it represents a tiny visual target which you may not accurately recognise in a busy city environment what with all the other visual road clutter about.

One solution will be to use very high intensity lighting to flood the path of the crossing with appropriate colour and texture (ie, red and crosshatched for don't cross, green and solid bars for cross, thus catering for red-green colourblind people too) (well, not really catering for them, there won't be any cups of tea and sausage rolls or anything).

That way, you don't have to be looking for and at a tiny little area in your field of vision, you just carry on looking at the ground surrounding your smartphone and when it changes colour, you take appropriate action.

Ian Tindale, Apr 28 2011

Not quite the same thing, but similar http://www.artlebed...erything/air-zebra/
[mitxela, Apr 28 2011]

painted ones... http://farm4.static...8876_3c30a8c167.jpg
[xandram, Apr 28 2011]

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       I have noticed that round these and other parts, in winter, the noonday sun can be very low, rendering everything silhouette. Perhaps, then, beaming light onto the tarmac is not going work well enough and we should, instead, be considering flooding each crossing with red or green paint, depending on walk/don't walk status. To aid the colourblind, the stop paint could be lumpy.
calum, Apr 28 2011
  

       the little green man seems to be disappearing from the post across the road and being replaced by one next to you as you wait for the lights to change. I would quite like this though.
po, Apr 28 2011
  

       Knowing something about high intensity lighting, "easily visible even in bright sunlight" is going to be very energy and materiel expensive.
MechE, Apr 28 2011
  

       The crossing area itself should be made from panels, red on one side and green on the other. When you're allowed to cross the road, the panels should rotate, to display the green surface uppermost.
hippo, Apr 28 2011
  

       [po]: The green man is across the road at a Pelican crossing and next to you at a Puffin (the more modern) crossing. I think this is something to do with the sensors Puffin crossings use to tell if people are standing waiting to cross.   

       I took my driving test not long ago and for the theory part I was told to revise crossings. I learnt all these useless facts and to my disappointment not one question came up about it.
mitxela, Apr 28 2011
  

       All this complexity could be avoided by a pair of trebuchets and rope nets, which could operate without affecting traffic flow.
8th of 7, Apr 28 2011
  

       Rope nets might not be strong enough for larger vehicles.
pocmloc, Apr 28 2011
  

       We have some painted all red, but I really like this idea! [+]
xandram, Apr 28 2011
  

       //very energy and materiel expensive// But what's the price of your life?   

       That would have helped a lot once a while back, forgot me glasses, waited at the crossing of the busy road, then saw the green man and wandered across the lanes, until I got close enough to see the green man was in fact a green Xmas decoration in the fag shop window...
not_morrison_rm, Apr 28 2011
  

       Erm, just to be boring, in one country (no names, but it starts with J) the light panels are red and green and the little men are black. Don't ask me why, I have no idea.
not_morrison_rm, Apr 28 2011
  

       // strong enough for larger vehicles //   

       Wire rope…
8th of 7, Apr 28 2011
  

       Rather than illuminating it, it would probably be hugely cheaper and easier to use something like e-paper, but red and green instead of black and white.
mitxela, Apr 28 2011
  

       Yes, but that not only has the disadvantage of being hugely cheaper and easier, it is also ecologically more ethical, which rules it out.
Ian Tindale, Apr 28 2011
  

       How about orthogonal sets of automated rollers to apply alternating contrasting coatings of quick-drying paint?
pocmloc, Apr 28 2011
  

       ////very energy and materiel expensive// But what's the price of your life? //   

       If more people die gathering the raw materials and in manufacturing than are saved by a safety device, it's less than ideal. If it saves just one like is very rarely a realistic argument.
MechE, Apr 28 2011
  

       //high intensity lighting, "easily visible even in bright sunlight" is going to be very energy and materiel expensive.//   

       How about one or a few lasers of the kind used in laser pointers (cheap) raster-scanned to "paint" the crossing with, e.g. solid bars for "cross" and crosshatching for "don't cross." Lasers should be cheap, added electronics likewise, mirror galvanometers not too expensive either.
mouseposture, Apr 28 2011
  

       Full sun intensity is ~1kW/m^2. Given the human eye response to red and green light, you'll need only about that in green, but significantly more (~120x) in red.   

       A high power 100mW red laser pointer will provide this intensity for a spot of .0000008m^2. Even if you choose only to do say two lines, 10cm wide, all the way across a street (6.8m minimum for a two lane road in the US.), you are illuminating 1.36 m^2. That's 1.6 million laser diodes (and scanning doesn't help, you still need to provide that much total illumination, a more intense laser for a shorter time). At a minimum of $20/diode, that's going to add up. More powerful lasers cut the number of units, but don't do much to the cost, as it tends to scale linearly, although you would save a bit on optics.   

       As far as the operating cost, if you use the most efficient light source available (very high end laser diodes, at about 80%), it's going to cost approximately $2000 per crosswalk per year in electricity.
MechE, Apr 29 2011
  

       Note that the above assumes this is reflecting off a bright white diffuse reflective surface. While concrete wouldn't be to much worse, asphalt would require much higher power to be visible.
MechE, Apr 29 2011
  

       Here's how you do it: a giant fresnel lens focuses sunlight through a small filter area, then another giant fresnel lens to straighten it out again. The system is movable to track the sun up to 45 degrees. A mirror can reflect light into the system when the sun is closer to the horizon that that.   

       When the sun goes down, you use an electrically powered light instead.   

       You use some sort of weather control system to make sure you don't have clouds blocking the sun.   

       The filters have to be able to withstand extreme heat and solar radiation. Maybe ruby will do it.
caspian, Apr 29 2011
  

       What is this “sun” of which you speak?
Ian Tindale, Apr 29 2011
  

       Well, the complete lack of this thing you call a sun (I have a photograph of it from my grandfather's time) means it'll work better here in the UK, due to an almost complete lack of competing illumination.   

       Old joke stolen from tv series. The president is talking to his science adviser about the uk. "Mr President, if god had wanted man to live in England, he would have given us gills".
not_morrison_rm, Apr 29 2011
  
      
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