Green light in private ambulance light bars! (Not IC)

[StonedChipmunk]

Saw many, many emergency vehicles on a drive from a clay trap shooting range back to school today. Strobes, LED's, rotating, all sorts of different colors. All working (duh).
Must have been some big emergency down here.
Anyways, my analysis concluded with these results:

Color ranking during broad daylight:
Yellow
Green
Blue
Red (light was shining on red causing it to not show as well)

Light type visibility during broad daylight:
Stobe
Rotating
LED
(Note: I say LED worst because the lightbar was one of those superthin ones... couldn't see it until actually next to it).

I also think that the flash pattern efficiency depends on the speed of the vehicle. If the vehicle is moving quickly, a barrage of strobes won't do much effect, since it will seem just like glare or something. On the other hand, synchronized strobes are less efficient while at a standstill, because a barrage of strobes catches the eye better because of the brightness, while synchronized strobes dont do much better.

[Robert Gift]

Fantastic stuff, Jim and Chip. Thank you very much.

Wonder why human eye is most sensitive to green and yellow.
Are we meanto be vegetarians who flee tigers?

Shucks, Monk.
I was gettin hot for LEDs. You burst my balloon.
I recall that 360s were "hotter" than early strobes for a while.

Our Code 3 light bar had two pods each side, each holding red, blue and white PAR36 bulbs.
When I coordinated the pods on their common rubber belt, it was much more effective.

The bar also had two PAR56 round headlight bulbs which I wired to the wigwag I built. So headlights and bar lights were coordinated.
(Maybe THAT was what waso effective.)
/o O o [ = ] o O o\

But all the 360s were in a row, so from thend you saw only one light flashing.

Our present Street Hawk has the inside rotators forward and outside rearward, so from the side you see two lights flashing.

[Jim_Ferer]

I think it's the design of the LED bar that Chip saw that made it less visible. The LED bars I've seen have universally been the best I've ever looked at. My amber LED arrow stick is far better than any other we've got.

What seems to set LEDs apart is the richness and intensity of the colors. The red, blue and amber are strong and unmistakable. White LEDs seem superfluous and can be mistaken for blue at a distance; I wouldn't use white in an LED array.

If it's true that the elements of visibility are intensity, color, and time (how long the signal is on) , then there's probably a difference between how the factors compare in daytime vs. night time. I would think intensity would be more important in daytime and color and time more important at night. So I'd try slowing down the flash rate at night and simplifying the patterns so that my vehicle looks like a stopped vehicle and not like a disco ball. I think my best pattern at night (and the array on my car has too many choices, if anything) is 4-4 right and left, not too fast. If I'm forming part of a lane closure or something then I'm doing whatever my part is.

If I had an emergency vehicle, I'd want to set it up with amber and my emergency color in the rear, let's say red. There would be two rear facing lights with a lot of area that would wig-wag while I was on the run but would change to steady-burn as soon as I put the vehicle in Park. The ambers would keep flashing. One advantage of this would be that it would be easy to distinguish moving from stopped from the rear.

[Robert Gift]

...vehicle looks like a stopped vehicle and not like a disco ball.

Ha! Goodescription.

I think my best pattern at night (and the array on my car has too many choices, if anything) is 4-4 right and left, not too fast. If I'm forming part of a lane closure or something then I'm doing whatever my part is.[/quote]

I don't understand.

...There would be two rear red facing lights with a lot of area that would wig-wag while I was on the run but would change to steady-burn as soon as I put the vehicle in Park. The ambers would keep flashing. One advantage of this would be that it would be easy to distinguish moving from stopped from the rear.

That is a great idea! Everyone should adopthat.

[Jim_Ferer]

Jim:I think my best pattern at night (and the array on my car has too many choices, if anything) is 4-4 right and left, not too fast. If I'm forming part of a lane closure or something then I'm doing whatever my part is.

Robert: I don't understand.

My light stick has eight segments. One of the options is for the four right and four left to wig-wag. It's the most intense warning choice on my stick.

When I'm forming part of a lane closure (we've go the right lane out, for example) I may be using the left directional pattern on the stick to keep people to the lane left of us. Remember, I'm in civil construction, so we're frequently doing lane closures and other diversions on bridges and highways. These closures are planned out, sometimes weeks in advance, and I know where I'll be.

[StonedChipmunk]

I take that back on the LED lightbars, they are the best. Saw one today, it nearly blinded me. It was, also, a few rows of LEDs instead of 1. By the way. the LED lightbar I saw yesterday was the 911EP Galaxy (just IDed it a few mins ago). Thats probably why visibility was terrible.

[q2bman]

Some leds stink while others rock. Design is important. I love the leds. They are in a league of their own. I also know that red halogen and strobe were brighter during the day and blue was brighter at night than red. But with leds, blue stings hard day and night! That is an intense color produced by an led. Red is bright as well day or night. LEDS are on my favorite list!!!

Strobe had to be randome to gather attention but the instant on and off of an LED make even the most simple alternateing pattern effective!


ROCK ON LEDS!!!!!

[zetronist]

ROCK ON LEDS!!!!!

I absolutely agree!!

[Daniel]

Here is my personal opinion on lights. This is not based on anything scientific, except my observations and preferences. All emergency vehicles, whether police, fire, or medical, should have 180 FPM blue rotors and blue halogen or LED flashers with a fast wig-wag pattern. Xenon strobes are less reliable and have too brief of a flash. Police should have all blue, fire would have blue with red, and medical would have blue with amber. Construction and non-emergency vehicles should have amber only. The US Forest Service gets the green lights ; their fire services can have blue, red, and green, and their law enforcement could use blue and green. Purple is interesting if there is some ultraviolet content (not magenta) and as an experiment, it could be integrated with blue for state police/highway patrol use, due to the visibility of UV-range purple over long distances.

[zetronist]

What is really needed is some kind of *federal* standard (I'm talking the Government here, not Federal Signal ) for emergency vehicle lighting.

What is confusing are all of the different state laws on the matter of lighting color and other requirements (like CA's steady burn to the front/flashing amber to the rear).

In one state, blue is for law enforcement and you have to pull over. In another state (i.e. mine, NY) blue is for volunteer fire fighters and it is a courtesy light, not an emergency light. So you don't have to pull over.

Someone from say, Florida, comes to NY and is driving through a town where there are volunteers responding to an alarm, and it is confusing for them.

There are some federal standards in place already. For instance the Federal DOT specs for ambulances REQUIRE an amber light to the rear on all ambulances in the USA.

Standardizing the light colors and other requirements would be a good idea.

John