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Tuesday, 2 March 2010
Dynamic cycle path lighting
This video, from the fietsberaad, isn't too clear, but what it shows is quite interesting. It's an experiment with dynamic cycle path lighting. The lights remain at about 20% brightness until a cyclist approaches, when they will increase to full brightness as the cyclist passes, reducing again over several minutes if there are no more cyclists nearby.
The idea is to retain a high level of social safety along cycle paths while also reducing the energy usage and light pollution which would result from full brightness lights at all times.
These experiments do, of course, also use LED lighting to further reduce the energy demand, and they are soon to appear more commonly across the country.
There are further stories about lighting, which include some other experimental schemes.
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Interesting. We could do with some of that round here in 'lighttown', where there's altogether too much light blazing away.
Wasn't there a blog about green lights, which don't disturb nocturnal animals?
Anyway, good initiatives.
I wonder how it works... Does it use a thermal sensor (like the one used in alarm systems) to detect movement. Because I could imagine that my velomobile would not show up (or at least has a 'low thermal signature').
Btw. about 1,5 weeks ago I spent the weekend with my parents in Stadskanaal (The Netherlands) and they have a stretch of cyclepath with lights you can activate. This time there is no sensor, just a pole with a button on it. I haven't tried it, because it was light when I went there. But you can see it in the YouTube video in my blogpost (around 2:13).
Will these adjust to ambient light? Under a full or near full moon, especially with snow cover, or with cloudy skies and snow cover in urban areas, eyes can adjust and provide far more depth than any lighting.
(If anyone ever wants to see ridiculous over lighting, visit Prague during the winter... it almost hurts).
Anneke - Assen is planning to bring more light to a recreational area near water, in order to increase safety. So as not to disturb animal life, green LED lights have been tested on the many bats flying around there at night. It was a serious research project by Groningen University. Result: intense white light attracts bats, thus changing their natural behaviour. Green light and no light at all make no difference to the number of bats, that is the researchers counted the same number of bats in the dark and under green light. As the green light is also cheaper than bright white light, Assen will probably install the green lights.
There is one detail I don't really understand: bats seem to be attracted to bright lights. In my opinion they should be, as bright lights primarily attract their prey (moths and all that), so following their prey seems to me utterly normal natural behaviour. But the ecologists will no doubt argue that it is in the bats' best interest not to offer them a concentration of tasty insects.
@ Frits, I happen to know why the lights attract insects, they navigate by the light of the moon, (or sun, depending on what insects)at leats moths, bees, flies etc do. So, bright lights are like a moon to them. Their eyes can detect the angle of the light, and with something as far away as the moon, they can safely navigate. Artificial lights however make them go around in circles till they reach the light, at which point they can no longer navigate at all. Bats have sonar (or whatever the word is in English) so they can always find insects simply by listening. And sure, the insects won't hang around a lightbulb waiting to be eaten, but that won't starve the bats.
Anyway, there are other nocturnal animals that benefit from the green light, right? Owls for example, and badgers etc.
Reducing the light overall is a very good thing. And it's not just nocturnal animals that are affected - not sure how green fairs with Astronomers. I know the current lights are particularly bad for astronomy.
@Anneke: this is turning into a biology lesson :-). True, insects use the sun and the moon as orientation. Owls, and badgers for that matter, are almost colour blind as are most animals except monkeys and apes. Green light to them only means that it is a bit darker outside which for badgers makes no difference as they are so shortsighted that even by daylight they mostly go by their smell and hearing. Owls on the other hand have eyes that are so light sensitive that green light to them is almost as clear as white light is to us; but the species living in our neighbourhood mostly catch their prey by sound. Dogs and cats ditto; dogs are in the badger category, cats more like owls. So essentially, the choice for green lighting is very human-centred. Green light looks good to us; most animals couldn't care less. But as it's alo cheaper in use I'm all for it.
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