Comments on: LED street lighting: Not as good as you think.

by: Popup

Tue, 06 Jan 2009 19:17:47 +0000

Talking about R-G-B LED configurations... Have you seen the Philips 'living colors' lights? (There are plenty of youtube videos around) A set of powerful R-G-B LED's in a cool package. (Comes in transparent or glossy black or white orbs. I think I've even seen it with an ipod dock.) You can control intensity and color with the wireless remote.
The only drawback is the price. (It's around USD100-USD300 depending on size.) I can't wait for a cheap knock-off at dealextreme. (And if possible, with a USB interface to control the LEDs from an computer!)

by: Chris L

Thu, 01 Jan 2009 02:29:13 +0000

Do you know anything about "induction" street lighting? My town is in the middle of replacing the nasty orange sodium lamps with them, and they do look nice and white, and are supposed to pay for themselves. They are supplied by this company: http://www.luxlite.com/

by: jeroen8

Wed, 31 Dec 2008 07:35:43 +0000

The lumen/watt values mentioned here are more the theoretical values which have been measured in optimum conditions without taking in account the loses reflection. On the renewable energy OliNo.org website they have measured the real lumen output of both a Low-pressure sodium lamp and a new state-of-the-art LED street lamp. This LED street lamp is using the newest Cree 100 lumen/watt LEDs. Look here for the results: The Low-pressure sodium Indal Industria Aurora Streetlamp Measured value: 67 lumen/watt The LED Streetlight Lioris Aduro 52 Measured value: 64 lumen/watt As you can the see the real measured values are a lot lower than the theoretical values. The LED street lamp has almost the same efficiency as the low-pressure sodium lamp. The advantages of the LED lamp compared to the low-pressure sodium lamp: - The light of the LED lamp more evenly spread on the road when multiple lamps are combined together with a fixed distance between them (no hotspots). - The light of the LED has a wider colour spectrum, so objects are better visible.

by: awollangk

Wed, 31 Dec 2008 00:25:59 +0000

Two things--

Thing the first:

The main flaw in TwoHedWlf's arguments are that the shape of the lights are not the only clues that indicate traffic lights to drivers. If they went to a single light that just changed color from green to yellow to red (There are individual LEDs more than capable of doing exactly that) his argument would have more merit that it might not be interpreted as a stop light. Any arrangement of three lights with a lit red light on top, a lit yellow light in the middle or a lit green light on the bottom will most likely be interpreted as a stoplight. Also moderating this is the fact that people tend to look for traffic indicators when approaching an intersection. The only times I don't actively look for indicators is when I've been through the intersection enough times that I know exactly where to look. In both of these situations if the lights are square instead of round (or even if there is just one light that changes color) I am unlikely to be thrown. I'll notice the difference, sure, but it won't create an unsafe situation.

Thing the second:

Luxim has come up with a light that has achieved 140 Lumens per Watt (http://news.zdnet.com/2422-13748_22-192842.html?tag=nl.e539) and they're promoting it as if it's a pretty big deal. It's not an LED, but the hoopla is pretty convincing and the bulb is REALLY small. About 16mm long by 8mm round. They were running the one they had at about 250 Watts which suggests it was putting out about 35,000 Lumens. They had it side by side with a 400 Watt street lamp and it was significantly brighter.

by: Changes

Tue, 30 Dec 2008 10:37:23 +0000

Your argument isn't without sense, but I've seen some square traffic lights already (can't really remember where, but maybe it was in Zagreb, Croatia), and there weren't pieces of glass and metal everywhere, so I can only assume the end result is pretty much che same.

by: TwoHedWlf

Mon, 29 Dec 2008 11:17:49 +0000

Sure, eventually. But the way your brain works while driving is that you don't look closely at much at all. You drive along glancing towards important areas and it's a matter of pattern recognition to alert you to anything important while ignoring anything that isn't. In this case you're likely to get a lot of people glancing towards the intersection and their brain instead of going "Round things! Traffic lights! Stop!" it'll go "Square things! Irrelevant."

Now if it would mean a couple minor crashes and handful of panic stops at intersections over the first couple months or dozens fatal crashes, I don't know.

by: Changes

Mon, 29 Dec 2008 08:07:48 +0000

Never let it be said that I trust humanity's intelligence, but I think even the dumbest people of our species would behave the same whether the lamp was square or round...

by: TwoHedWlf

Mon, 29 Dec 2008 04:09:47 +0000

I'd say they're still round because all others are still round. I don't think it would be a very good idea to just slowly change them over, you'd want at least consistency of shape within a city. People might not immediately notice square lights when they're used to round for example and end up running through them. So you'd have to replace an entire city worth of lights simultaneously...Imagine the chaos that would cause.

by: phrantic

Sun, 28 Dec 2008 17:15:33 +0000

And why are they still round? Art Lebedev has proposed square traffic lights that seem to make more sense. More surface area for the same amount of space.

by: Changes

Sun, 28 Dec 2008 08:45:58 +0000

I hate incandescents with a passion and I'm a huge fan of LEDs, CCFLs and really any other illumination method, but there is one good thing about having hideously inefficient incandescent bulbs in traffic lights: if snow blocks the window, the heat from the filament will eventually melt it off.