You’ve got your normal, run of the mill traffic lights. They work fine and dandy. But… every now and then, you run across one of those worthless traffic lights that look as if the light is bouncing off a mirror before you see it. Instead of the light cover being textured, it looks like a smooth fish-eye glass lens. You can only see these things from certain angles, and as a result, you sometimes don’t know what color the light is until you are just about on the line of demarcation at the intersection. What in the world is the advantage of these lights supposed to be? Why would a government think that using these traffic lights was a good idea?
Just a WAG, but they probably use less power: If you’ve got the same amount of light coming out the front, and less off to the sides, it’s cheaper to run it. Of course, they’re theoretically designed to be seen from an appropriate distance, but I don’t doubt that there’s a number that are messed up.
I’ve only seen them used for left turn signals. Specifically, a red “no left turn” light. If the straight-through traffic could see it, it would be confusing, so it’s designed to be only visible from the left turn lane.
I’ve only seen them in the US though. In Japan, if straight traffic is allowed but right turns are not, it will be indicated by a green upward (“forward”) arrow. A plain round green light means you can go forward, left or right. The American system is more sensitive to alignment and positioning, but requires less thinking on the part of the driver. (Typical, isn’t it?)
These lights are especially hard to see when the sun is low in the sky, or when the wind is whipping the lights around. I find that moving my head around so I can see it from different angles usually helps. Of course it makes me feel like an idiot. “Pay no attention to the strange man who thinks he’s an owl, Jimmy. Don’t get too close!” Luckily, these lights are (so far) rare in my area.
I do see these primarily as left turn lights, but the one that got under my skin today was for general use. The city of Houston just annexed the area I was in, and whaddayaknow, they done come in and “improved” things… typical. :rolleyes:
I think the purpose of these lights is to reduce confusion at intersections where the lights for one direction could otherwise be seen by other directions or too far away. They seem to be commonly used at Y intersections or other intersections at acute angles. There’s also a place near me where there are two lights within about 200 feet of each other, and they have this type of light for the further traffic light, presumably to keep people from fixating on that light and running the previous one.
OK, if they’re not for left turns, I’m inclined to agree with Chronos - it requires less power. And there may still be nearby streets which can get confused - e.g. a road that crosses the main road at a shallow angle. I can’t think of any other advantages over standard lights. Still, if you couldn’t see it well before you got very close, it must have been misaligned. Driving slower might help though!
Actually I think Mr. Freely got it. I once run a red light because another light 100 feet farther down the road was green. No accident that time, and I’ve been careful ever since, but a directional light would have pevented it.
I don’t think we’re talking about LED lights here, though those can be made very directional as well. For some reason I’ve only seen LED signals used on railways and railway crossings (level crossings). I wonder why?
In my hometown in suburban Boston, there were several of these lights installed around the town. Usually, they were at intersections where there was only a single set of lights (no left-turn-only lights). They could be seen from either a long distance away, or when you were right underneath them. Annoying as hell, as everyone had to come to a near-stop because nobody could tell what color the signal was.
I could never decide if it was because of some half-wit bureaucrat whose brother-in-law built these things in his garage, or because of some self-appointed expert who decided to solve all the problems we townsfolk were too ignorant to know we even had.
I’ve seen both the LED lights and the smooth-looking ones the OP is asking about. Most often, with the LEDs, only the red is LED while the other two are regular-- Presumably, this is because red LEDs are cheaper, for the hardware at least. As for the funny, smooth ones, I’ve seen them at perfectly ordinary, well-spaced, perpendicular intersections, too, so either the “don’t confuse other drivers” explanation isn’t quite on the money, or someone who installs them isn’t.
Neutron, they’ve decided to start installing these buggers in my area now. The red ones are fine. The green ones suck the big turkey! They have to be the most disgustingly bright lights I’ve ever seen!
This is one area where the French (who should’ve thot it ?) are way ahead of any other country I know. They have added the charming feature of a miniature repeater light in eye height for a motorist in an average European car.
Very civilized, especially if you’re first in line.
I’ve seen these as main lights, not just turn lane lights. And of all things, they were on multi-lane highways where the speed limits are 45-55 mph (70-90 liters/hour). But you can’t tell the color until you’re right at the point where you should be braking if it’s red.
OK, it’s a power saving device. Does that matter to the poor schmo who got sideswiped because he accidentally ran a red light?
I think you’re all wrong. They ARE introducing a lot of LED traffic lights, and they DO use less power an last longer. But in my experience you can see the LED traffic lights over a large range of angles. The OP is complaining about lights that you can only see from a very narow range of angles, and that’s something different.
I’ve seen these lights , too. They seem to be traffic lights with a Fresnel len in them. Fresnel lenses are lightweight large aperture lenses that are very flat. They used to be very popular fr the rear windows of VW buses and the like. They are easily fabricated out of plastic, and are very thin and lightweight. You can get them from Edmund Scientific and other such specialty suppliers.
The interior of such a light almost certainly has a light placed at the focus of the Fresnel lens, and either the fresnel lens itself is made of colored plastic, or has a colored plastic filter behind it. The advantage of this system is that it is very efficient at sending most of the light directly forward. The disadvantage is that very little of the light goes anywhere else, is if you aren’t directly in front of it you don’t see it. Such system clearly saves energy in the long run. It is a pain in the neck if you want to see the signal and you aren’t in front, but that’s the price of progress.
We’ve got at least one set of these damn lights where I live in Frederick, MD. it’s along US rt 40 a very main road and it’s used as the main set of lights. even going 45 you can’t see them very well. what’s really screwy is I can see the next light down the road BEFORE I can see the one I’m coming too. the good thing is that our lights are pretty well timed so if I can see one is red the other one probably is too. and yes the worst time to drive there is during rush hour when the sun is setting. dumb people.
