Why Do Most Ambulance grille Lights Flash Simultaneously Instead Of Alternate?

[AshSkip]

Quick question for all of you Garus and Light Lovers...I should actually know the answer since I worked EMS for some time. I have noticed on every unit we had at the station, that the grille lights always flashed simultaneous instead of alternately. Even recently on new rigs with modern LED lighting, I still see this. Im not sure if I've ever even seen an ambulance with grille lights that dont flash together come to think of it.


Since I see most people say that grille lights are more effective on patterns that alternate or dont flash at same time, My question is, what is the reason for this on ambulances; if there is a reason at all? I have been curious about this for some time, but never took the time to ask. I thought who better to ask than the ELB board.

 

[Squad-6]

Good ? also I never see em with HLF

 

[dmathieu]

Regulating authority approved flash pattern, along with top corner, all sides, and center front whit lights.


You guys who really know, and have the approval numbers chime in.

 

[NJEMT]

My ambulances for one ambulance company have alternating grill lights. All have headlight flashers. One ambulance at another company has headlight flashers but we turn them off because the ambulance manufacture didn't bypass the clicker on the truck, so every time the headlights flash you hear the clicking and it is annoying so we turn it off.

 

[nerdly_dood]

My ambulances for one ambulance company have alternating grill lights. All have headlight flashers. One ambulance at another company has headlight flashers but we turn them off because the ambulance manufacture didn't bypass the clicker on the truck, so every time the headlights flash you hear the clicking and it is annoying so we turn it off.

The headlight flasher module IS the clicker. The truck's turn signal flasher is a separate clicking entity. They click because it's a mechanical action opening and closing the circuit, except on some newer cars where they do it with the car's stereo.

 

[lite-em-up]

I'm pretty sure that it's the KKK spec pattern. Grill lights on with white center light, alternating with red outer box lights.

 

[nerdly_dood]

I'm pretty sure that it's the KKK spec pattern. Grill lights on with white center light, alternating with red outer box lights.

BTW this title comes from some government drone. No actual human being came up with the idea "Hey, let's pick an awful name for this set of rules we came up with!"


BEEP BOOP previous section called KKJ these are in alphabetical order the next one is KKK BEEP BEEP BOOP previous section called KKK these are in alphabetical order the next one is KKL BOOP BEEP

 

[HILO]

The Ambulances in Grand Prairie have HLF's Dodge and Ford. Both GP an Dallas FD have alternating grill/bumper lights. Most of the various city units in my area have alternating grill lights.

 

[pdk9]

I'm not sure I agree with the OP that grill lights seem to flash simultaneously a lot; I think it might just be a local trend. Overall in the US, I honestly think that most ambulances being produced these days do have alternating patterns for the grill lights (I think that the simultaneously-flashing grill lights was mostly with halogen grill lights and with the setups of few departments, at least from what I've personally seen). To be honest, I actually like it when 2 grill lights flash together IF there is a HLF being used (in smaller grills, IMHO, some of the smaller grill lights get drowned out at night by HLFs, but that flashing simultaneously improves their competition against the high beam's power, ie I've seen a bunch of E-series vanbulances with Lin3 grill lights and they're nearly invisible when the headlights are on or flashing in a wigwag pattern)...on the other hand, FDNY's grill lights alternating with box lights look great IMO, and the larger grill lights flashing simultaneously do not get washed out

 

[Eric1249]

We have 2 ambos. Older one has strobes in the grille and they alternate and the other has gen 1 leds and they are not synced. Both have strobes in the headlights.

 

[tnems7]

For you history buffs, a fellow human being actually did select the lighting pattern - his name - Mel Globerman. Mel was an electrical and automotive engineer with the Federal Supply Agency (General Services Administration) who helped develop the original and next four editions of the Federal Specification for Star of Life Ambulances, aka, KKK-A-1822. A lot of the original research was devoted to creating a unique flash pattern for ambulances, and the simultaneous flashing grille lights alternated with the Upper Level box lights. The grille lights were on when the Upper level center white was flashing, along with the side facing intersection lights. When these were sealed beam lights, flashing box lights and grille lights in this manner meant the electrical load was balanced. This became less necessary as strobe, and the now state of the art LED lights, became available.


When I helped revise the Tennessee Ambulance Specifications and lighting regulations in 1988, the Whelen strobe ambulance strobe power unit was around $2100. Three four pack stobe supplies were around $1200. If the strobe cables were laid along side each set in the loom, these lights tended to auto-synchronize, so you still got the upper and lower switching. If not, we didn't see any reason to get so bent out of shape if the strobes didn't sequence properly in strict KKK patterns. The KKK standards were also written to begin to recognize the amount of light output from each presenting side, or "face" of the vehicle, just as the current NFPA standards are written. Ambulances in KY and TN also began to place more than one amber lighthead to the rear, so we just required the center amber to the rear as a minimum. We also allowed Traffic Clearing Lights in white to count as the front white light, and to allow the white light to be incorporated in light bars.


So my friends, there was reason for the madness, and the existing practices are due in part to the tradition and distinction of ambulance lighting more than to modern standards for emergency warning display.

 

[AshSkip]

We have 2 ambos. Older one has strobes in the grille and they alternate and the other has gen 1 leds and they are not synced. Both have strobes in the headlights.

Im glad some are going to alternate. The new rig (less than a month old) at our station has led's in grille but they flash together.

 

[JohnMarcson]

If you follow federal KKK ambulance specs 100% that is what is called for.

 

[Solvarex]

Folks should pay closer attention to the KKK specs. They haven't changed in decades for good reason - THEY WORK.


When every manufacturer came out with qua flash, quint flash, hyper flash, and all other manner of seizure-inducing patterns, everyone fell for it and figured these new patterns were "attention getting" and "good". In our quests to be individually different we didn't want to have some plain old boring flash pattern, we wanted distinct, flashy, and random.


The problem is those might look good up close, but if you only wanted to produce a signal for the drivers 10 feet in front of you we would need only a couple of dash lights and a 30 watt siren. Random blues look like garbage from a hundred feet out. Lack of synchronicity hurts a signal more than anything.


That's not even getting into split lightheads, the dumbest idea to come along in lighting in decades. Nothing quite like paying hundreds of dollars on a high end box light and then HALVING its effectiveness by flashing only 50% of its LEDs at any given time.


My vehicles use flash patterns no faster than 75 FPM and I sync as much as possible. From ten feet out or a thousand the signal is clear and highly visible, and certaint distinct when everyone else is doing the random blur nonsense.

 

[JPolston]

My guess is it's just up to the dept. or service the ambulance is used for. Our ambulance has its grill lights set to a alternating quad flash. Our sister town also has it set alternating. Some of a close cities are alternating, some of them they have flash together.

 

[HILO]

What we, the collective of ELB, have to remember, is that maybe a quarter of EV operators pay attnetion or otherwise care about the lights. The majority of EV operators pay little attention. I have DPD friends that refer to a Liberty as a Visabar, because that is what they started out with. They are happy if the lights flash. This is even more evident with fleet managers, purchase departments, or other decision makers. When DPD started using Liberties, a few of us started changing the patters. Brass issued a directive that patterns will not be changed. Then they had every liberty set at the same pattern. Engines, trucks, and Ambulances usually run with whatever pattern is set from the manufacture. Heck, most Ambulance operators have no idea why there are two levels of lights.

 

[Muxlow]

Its the same deal in Ontario here. Today i saw a EMS truck going down the road code 4, roof lights on, HLF going and 2 red grille lights, both lights flashed at the same time. On some other trucks here iv seen them alternate red/red splits.


Some other EMS services around here had the same setups, solid colour flashing at the same time in the grille and other trucks split red/red.


The same question came to mind.. why are both these nice grille lights flashing at the same time and not alternating. With the HLF it looked a little... odd from a distance

 

[Solvarex]

The same question came to mind.. why are both these nice grille lights flashing at the same time and not alternating. With the HLF it looked a little... odd from a distance

It obviously caught your attention. Mission accomplished.

 

[SafetyLighting]

As previously mentioned, the location and flash patterns, duty cycle, etc are per Federal KKK spec. Not every state cares about the spec but certain states, ie RI, require an ambulance to meet the KKK spec. Furthermore, if an ambulance doesn't meet the spec, it's a good way to lose a lawsuit if involved in an accident. Long before the NFPA starting suggesting that the white lighting on fire apparatus should be shut off on scene, the KKK spec required it on ambulances.

 

[spoda81]

I was told that KKK specs were set so the flasher switch had 2 settings, primary and secondary so that an ambulance could be identified comming toward you with the center white light and grille lights flahing alternaling with the the 2 outer reds, when the ambulance was parked at a scene the driver would flip the flasher switch to secondary position to shut the white and grille lights off but its a pain in the a## to rembember to do that Just put in park and get to work

 

[foxtrot5]

I was told that KKK specs were set so the flasher switch had 2 settings, primary and secondary so that an ambulance could be identified comming toward you with the center white light and grille lights flahing alternaling with the the 2 outer reds, when the ambulance was parked at a scene the driver would flip the flasher switch to secondary position to shut the white and grille lights off but its a pain in the a## to rembember to do that Just put in park and get to work

IDK if KKK adressed switching options specifically but yes, there is supposed to be a way to disable the flashing white when not "requesting right of way."


Now, ask me how many EMTs/Paramedics I've seen actually turn off the flashing white while on scene... or drive to the hospital with the side flood lights on... or, well you get the point. :duh:

 

[Solvarex]

I believe most manufacturers of ambulances and fire rigs now wire the lighting so white automatically shuts off when the vehicle is put in park.

 

[emtanderson51]

I used the manual switch for Primary/Secondary all the time at night in the snow. KKK is one of the most effective patterns out there. I cringe when the grill lights alternate.....awful. Same with the box lights. You get some yahoo in the dept that thinks they know better and start messing with the flasher and you end up with a mess.

 

[firebuff17]

So my question is why is there a primary/secondary switch? The ambulances I ride in meet the KKK spec and have said switch. While switching from primary (everything on) to secondary (reds on box and single amber in rear) does kill the white center, it also kills the red grill and red front fender. Doing so also breaks the 2 levels of lighting to help define size and location of vehicle. While 90% of the time I park in driveways and turn all warning lights off, There are times where I need to park in traffic and having grill and (probably more so) fender lights would be beneficial. So having that switch does not make sense to me. Can someone inform me what it's designed purpose is for?

 

[Eric1249]

personally I think alternating in better then simultaneous. There can be that one second when someone looks and it could that time when they are both off because they are simultaneous. Then again they should see all the other lights.

 

[tnems7]

firebuff17,


Here is the answer to your question yoy presented.


Besides switching off the upper level white front warning lamp - indicating the vehicle is parked and no longer requesting right-of-way, the major reason why the grille and side lights switch off are attributable to "vehicle electrical load management". When a typical ambulance is parked vs. moving, the alternator output drops substantially. While there is an electrical idle control module, the current at idle is still much less than when the vehicle is in motion at road speed. Add engine compartment heat with a parked vehicle, and alternator performance decreases even more. (Old timers, remember when we raised the hoods of our emergency vehicles while parked and idling on-scene. I still see police vehicles doing it today.)


Also, fog will bounce back grille lights or HLF, the same reason the white lamp may be switched off while the vehicle is in motion. The specifications were not written specifically for LED lighting. While the current consumption of the warning system is now much less with LEDs, many ambulance services prefer to maintain the original KKK-A-1822 light patterns.

 

[Torpedo]

I always thought front flashers pair flash because it is easier to see which turn signal is on if turning. Now that I think about it that's pretty stupid on my part. I chose it on my resto because I didn't want it to look like a stopped school bus alternating pattern. That and more is more, meaning if both sealed beams are burning there's more of a chance of being seen, hypothetically speaking. Very good question and reply chain.

 

[HILO]

firebuff17,
Here is the answer to your question yoy presented.


the major reason why the grille and side lights switch off are attributable to "vehicle electrical load management". When a typical ambulance is parked vs. moving, the alternator output drops substantially. While there is an electrical idle control module, the current at idle is still much less than when the vehicle is in motion at road speed. Add engine compartment heat with a parked vehicle, and alternator performance decreases even more. (Old timers, remember when we raised the hoods of our emergency vehicles while parked and idling on-scene. I still see police vehicles doing it today.)

Uh...not really. Most modern Ambulances are diesel and come equipped with PTO from the factory. Press the parking brake and the PTO rises the engine RPM to boost the larger or dual alternators. Gas engine Ambulances have a simular set up.


As far as engine heat goes, that is what the chrome exhaust vents on the hoods are for. CHP figured out that opening the hood all the way does not help displace heat, as the fan pushes the heat towards the hood, which directs the air flow back to the front of the engine, which recirculates back from the fan. The more effective way is to open the hood about a foot or so, usually propped up with a liter sized bottle of water. That allows fresh air to come in, and all the hot air to be pushed away underneath the car from the back of the engine bay. CHP started putting louvers on the hoods of K9 and other units.