3 ms·

Probably because including two unused bulbs is cheaper than custom-making a single-bulb traffic light. (Also, people who are used to seeing a set of three bulb

Probably because including two unused bulbs is cheaper than custom-making a single-bulb traffic light. (Also, people who are used to seeing a set of three bulbs might not recognize a single red light as being a traffic light at all.)

kuschku 10y ago
Actually, it’s not that easy. German traffic lights are a modular design, and ones with only two or one bulb are common. (You can stick as many modules together as you wish, or remove them)
- pluma 10y ago
  That doesn't sound entirely true. I've only seen one-bulb versions for flashing yellow lights (which are sometimes used on crossings to indicate "pedestrians are crossing" at difficult crossings, typically when more than two roads meet and the pedestrians could easily be overlooked). I've only seen two-light versions for pedestrians (i.e. red and green). I think I've seen other one and two bulb versions on non-public roads (e.g. industrial sites) but that's about it. I've never seen a version with four bulbs. And you make them sound more modular than they are: while the part containing the bulb seems to be generally modular the case containing these modules is generally fixed for a certain size. So adding or removing modules after they are deployed is not as straightforward (except maybe for temporary traffic lights). I've actually seen the auditory clue box (whatever it's called -- the ticking thing at crossings to help blind pedestrians cross safely) replace one of the bulbs (on three-bulb lights where there is a redundant second red bulb) instead of being added below the traffic light.
  - kuschku 10y ago
    Actually, I’ve got a few intersections right near me with such examples. There’s a traffic light for the lane straight forward. Directly next to it is one for those turning right. The forward light has Red, Yellow and Green, the turn lane’s light has only Yellow and Green (both with the arrow overlay). At another one, there’s lights for busses added below or at the side of the existing light, adding one, or two modules (below or at the side).
    - pluma 10y ago
      Where in Germany are you? I forgot about turn lanes (they often omit the red light when the red phase would be shared with the regular traffic light) but I've never seen bus lights. Might be a regional thing.
deleted 10y ago
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labster 10y ago
In California, I've seen single-socket traffic lights in all three colors. So it wouldn't have to be custom-made. The green ones usually have a directional arrow forward (amber and red usually blink) so they could probably accomplish the same effect with stock parts: red arrow pointing right in a single socket.
iopq 10y ago
Just don't put in new bulbs, then

kuschku 10y ago

Actually, it’s not that easy. German traffic lights are a modular design, and ones with only two or one bulb are common. (You can stick as many modules together as you wish, or remove them)

pluma 10y ago
That doesn't sound entirely true. I've only seen one-bulb versions for flashing yellow lights (which are sometimes used on crossings to indicate "pedestrians are crossing" at difficult crossings, typically when more than two roads meet and the pedestrians could easily be overlooked). I've only seen two-light versions for pedestrians (i.e. red and green). I think I've seen other one and two bulb versions on non-public roads (e.g. industrial sites) but that's about it. I've never seen a version with four bulbs. And you make them sound more modular than they are: while the part containing the bulb seems to be generally modular the case containing these modules is generally fixed for a certain size. So adding or removing modules after they are deployed is not as straightforward (except maybe for temporary traffic lights). I've actually seen the auditory clue box (whatever it's called -- the ticking thing at crossings to help blind pedestrians cross safely) replace one of the bulbs (on three-bulb lights where there is a redundant second red bulb) instead of being added below the traffic light.
- kuschku 10y ago
  Actually, I’ve got a few intersections right near me with such examples. There’s a traffic light for the lane straight forward. Directly next to it is one for those turning right. The forward light has Red, Yellow and Green, the turn lane’s light has only Yellow and Green (both with the arrow overlay). At another one, there’s lights for busses added below or at the side of the existing light, adding one, or two modules (below or at the side).
  - pluma 10y ago
    Where in Germany are you? I forgot about turn lanes (they often omit the red light when the red phase would be shared with the regular traffic light) but I've never seen bus lights. Might be a regional thing.

deleted 10y ago

[deleted]

labster 10y ago

In California, I've seen single-socket traffic lights in all three colors. So it wouldn't have to be custom-made. The green ones usually have a directional arrow forward (amber and red usually blink) so they could probably accomplish the same effect with stock parts: red arrow pointing right in a single socket.

iopq 10y ago

Just don't put in new bulbs, then