Orange halogen street lamps - do they decrease night vision for drivers?

Question

Since blue mercury vapor lamps have been replaced it seems harder to make out the pavement, curb, parked cars ahead etc in the dark. Anyone else? I'm not the only one. If concrete is yellowish and so is the light, it tends to wash out the object. For example yellow filters are used by skiers to better make out bluish shadow detail in the snow. Anyone have ideas or information?

Answer 1

yellow colored lights are actually high pressure sodium lights. They do have a tendancy to mask objects of the same color but the output is greater than metal haleid.

Answer 2

funny, the way i was always told it was both:

a/ sodium vapour was the most efficient choice, especially important as most of these lights were put in as replacements during the oil crisis or something (replacing older incandescent and gas lamps). don't know if that's true, but getting the greatest light output per watt input is a compelling argument when you're illuminating many miles of road, some of which may not actually get used worth a damn for several hours of the lit period.

b/ it's actually beneficial for nightvision; red would be an even better choice, but both drown out tail (+ brake, stop) lights and probably have rather unpleasant mental effects on anyone subjected to it for too long! a dim orange glow allows you to still see quite effectively (the fact you can actually detect the colour shows it's still fairly bright and you're not yet using the more sensitive, but lower-resolution and long reaction-time monochromatic "rod" cells in the retina) but doesn't have the same effect on night vision that, say, a blue light of similar intensity would have on your ability to see in the near-dark (moonlight, starlight) --- again, important particularly e.g. at the edge of town where you may be going from sodium-lit roads to unlit roads and need to have your night sight operating efficiently.
(my own road, and it's sidestreets, still seem to use old mercury vapour bulbs, or something similar, in their classic-style lamps, whereas the main roads they join onto all have "normal" sodium lamps that start off a pretty pink colour when warming up then move into mechanical orange)

This is why france and some other european countries specified pure yellow headlight bulbs for all vehicles for a very long time (i have in my not-so-distant childhood taken roadtrips to france where we had to put temporary yellow dye on our british car's headlamp visors) and I personally think that HIDs, whilst looking pretty cool with their high-powered "daylight effect" beams, are a terrible idea so far as overall road safety is concerned. It's probably also why tail lights, brake lights and fog lamps are red in the first place.

PS never mind skiers having yellow lensed glasses - did you never see those magazine adverts for similarly hued "anti glare" drivers' sunglasses? The idea is probably universal, not merely because of the slight blueishness of snow, but cutting out blue rays in general that are more piercing and glaring. My own drivers glasses are wierd... they do crazy things to colour... not yellow lensed, but they appear greenish-brown whilst deepening (therefore darkening?) blues and greens, and enhancing reds, oranges and yellows to a startling degree, without having a great effect on whites. I'm tempted to see what happens if I wear them at night.

Answer 3

Those are not Halogen lamps in the street lights.
They are sodium vapor lamps.

Most areas have changed to the sodium vapor lamps from the mercury vapor due to the risk of mercury pollution in the environment.

The other choice for them to change the lamps to was Metal Halide lamps (blue white) which are not polluting. The problem with changing to those is that you have to change all of the electrical circuitry that drives the lamp. That is why they chose sodium vapor it takes the same circuitry as the old mercury vapor.

Answer 4

-- Orange 'halogen' street lamps. It is a sodium (Na) filled lamp.
-- The human eye is not equal sensitive for every color. It is (almost) maximal sensitive for the sodium lamp. So the choice is very good.
-- The lamp is monochromatic, so you see all the visible objects in one orange color with different brightness.

Answer 5

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