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Dimmable Warning Lights: Part 2

By Bill Adams

Dimmable Warning Lights” is a misleading title. I originally thought the proposed changes to National Fire Protection Association (NFPA) 1901, Standard for Automotive Fire Apparatus were to allow dimming warning lights in the blocking the right-of-way mode. After reviewing some of them, the proposed changes appear to allow or mandate a second warning light setting in the blocking the right-of-way away mode for use at night. Part 2 is a continuation of my nonscientific, unsubstantiated, and biased opinion on the supposed recommended change(s). Have patience with meandering viewpoints.

You Can’t Fix Stupid
An American comedian’s axiom, “You can’t fix stupid,” ought to be considered when contemplating changing an existing warning light configuration. I interpret stupid behavior as a person doing something irresponsible or reckless or even illegal. I also believe drivers demonstrating such conduct may be the direct cause of the majority of collisions with fire apparatus when parked in the blocking the right of way mode. Some examples include:

  • Activities such as abusing alcohol and drugs (either legal or illegal) to the point that drivers become impaired and lose consciousness have caused accidents.
  • Operators of commercial and passenger vehicles being distracted when texting while driving has caused accidents—to the extent where some states have prohibited texting while driving.
  • Operators of commercial and passenger vehicles who willfully exceed posted speed limits have caused accidents.
  • Operators of commercial and passenger vehicles who drive at speeds excessive for inclement road conditions have caused accidents.

A person driving in a self-induced, highly impaired condition is just as likely to run into a solid brick wall as he is into a fire truck regardless of the type warning lights a rig is equipped with and regardless of the lights’ mode of operation. All four examples above demonstrate not only stupidity but illegal behavior that could be the cause of the majority of collisions with stationary fire apparatus. Has anyone researched the percentage of collisions with fire apparatus in the blocking mode that were caused by impaired drivers or texting drivers or speeding drivers or drivers operating too fast for road conditions? It might be interesting, but it also might ruin a narrative.

It is a possibility—and not an accusation—that safety gurus might be looking for a quick and easy fix to compensate for the illegal behavior of stupid drivers. Warning lights may have become an easy target because society may want to blame someone or something for ineptness in enforcing existing laws. Changing the mode of warning lights when blocking the right-of-way may have little to zero effect on what could be 99 percent of the drivers causing collisions with fire apparatus. Doing something might make some people feel good, however, it may not directly address the problem and undoubtedly will increase the cost of fire apparatus—perhaps needlessly. Has anyone estimated what the cost will be per rig—you know, a true cost benefit analysis?

I don’t think warning lights in any mode of operation will prevent a driver suffering an unexpected medical emergency from crashing into a rig. It is highly unlikely a second mode of operation for warning lights when blocking the right of way will prevent an impaired person from driving, or a driver from speeding, or driving too fast for inclement weather conditions. Stupid people do stupid things regardless if it is day or night.

If research in the form of data and testing can justify the proposed changes, I’m 100 percent for them. If current lighting in the existing blocking mode is being used as an excuse for illegal behavior by stupid people, then I am against them—both the changes and the stupid people.

Perception of High and Slow Warning Lights
People associated with the fire service know what warning lights are signaling and know what they should do when operating civilian vehicles. Firefighters can differentiate between a police car, fire truck, and ambulance coming down the street. Quite a few can even tell what engine company is in front of them and the manufacturer of the rig coming up behind them. Most civilian motorists have no clue and couldn’t care less about what’s coming at them, or behind them, or what’s stopped in front of them. Most would probably like to know what the warning lights want them to do. When discussing “changing modes” could be an appropriate time to address informing the general public what to expect when they see a particular warning light mode or pattern of operation.

As an example, I venture that most motorists approaching slow-flashing stationary red or amber lights are inclined to slow down and prepare to stop. High-mounted, slow-flashing, alternating amber lights usually means one of two things. The first is a school bus is stopping and soon will activate its red flashers. The second is there’s probably something very large up ahead that might not be moving, and its in my best interests to slow down and not hit it. Slow-flashing alternating red lights mounted high means it’s probably a stopped school bus and, by law, I have to stop too. The second thing alternating flashing red lights mean is there’s a railroad crossing ahead with a train approaching. Reasonable people might not want to ram the Midnight Express or let it hit them.

I believe the high and slow theory is generally accepted because if it isn’t actually law, it is commonly accepted nationwide for school buses and railroad crossings. What’s good for the goose might be good for the gander. Bear in mind that when contemplating a change in the blocking mode on fire apparatus, it has to be done on all four sides of the vehicle as there is no guarantee the rear end will always be facing the lane being blocked.

It appears school buses are starting to use LED technology. School buses may be changing their lighting to LED for financial savings in maintenance, durability, and longer life and not because of inadequate performance of incandescent or halogen lighting technology. Did anyone think to inquire? If slow-flashing incandescent or halogen red lights work well and are legal for school buses and railroad crossings, they might work well for fire trucks in the blocking the right-of-way mode. After all, I believe they have in the past. Imagine a nationwide framework (to use the British term) where on public highways slow alternating flashing red lights of a minimum size with a maximum flash rate and a maximum intensity means to STOP. It is an interesting concept even doable with LED technology. Current NFPA criteria could be modified, perhaps with a temporary interim amendment (TIA), to implement the same with red and/or amber lights on fire apparatus in the blocking mode. It could be used as a “trial balloon” rather than changing the standard—until accurate and detailed research can be completed.

Minimum or Maximum
Supposedly the NFPA 1901 warning light technical requirements were established decades ago with the technology available at that time. The requirements deserve a look-see and reevaluation. One item to point out is that the Optical Power Requirements in Tables and are minimum requirements established long before LED technology became popular. Depending on the vendors asked, today’s LED warning lights are anywhere from 5 to 80 times brighter (to loosely use the terminology) than previous lights. If previous Optical Power Requirements were adequate before, it seems plausible to keep the current power requirement tables and call them the “maximum” allowable. LED technology could still be provided without allowing lighting so intense it burns eyebrows and causes permanent optical damage.

Define and Prove It
Some of the so-called problems with the existing NFPA 1901 lighting standard identified in part 1 were that LED warning lights allowed in the existing blocking mode are too bright, too hazardous, too confusing, too irritating, too blinding, too fast, too intense, not properly synchronized, and too dazzling. If the above conditions can be too much, then what is just enough, or what is acceptable? A condition should be identified scientifically or statistically as should its high end of acceptability before it can be claimed the condition has been exceeded. Identify what the condition is, explain how it is exceeded, and then propose how to fix it. That isn’t asking too much.

NFPA 1901 has an established standard in place for warning lights. There should be a valid reason to modify or eliminate any existing requirement. An excellent reason is the existing one is not working. I agree. Just prove it.

I am not disparaging the educated—especially those well-versed in the “lighting” arena. When advocates are making their case to the masses who may not be as well educated, it would be beneficial if the language used is explained in understandable terms. Brightness, intensity, and ambient light conditions can be as confusing as lux, lumens, and candela-seconds/minute.

Would it be blasphemy to suggest the NFPA may not be the appropriate or best venue to mandate criteria for emergency vehicle warning lights in blocking the right-of-way on public highways? There’s more coming.

BILL ADAMS is a member of the Fire Apparatus & Emergency Equipment Editorial Advisory Board, a former fire apparatus salesman, and a past chief of the East Rochester (NY) Fire Department. He has 50 years of experience in the volunteer fire service.


  1. I have said for years that the school bus lighting is probably the most effective. High, slow with some burn time of the light. Also bring back the Beacon Ray light. The slow rotator draws the eye to the hazard just like the beacon at an airport or the lighthouse on the coastline. The Las Vegas effect of dozens of flashing lights can be confusing especially at night or in foggy conditions.

    Also the traffic director lights are useless because they are so small. Check out the size of the traffic director lights the highway department use. They are bigger than a sheet of plywood, size does matter, and here again slow flash.

    I’m no expert on anything, but just because the NFPA says so……… doesn’t mean it is so.

  2. A couple things, why do you have to diffrentiate commercial and passenger vehicles in the same sentence when the sentence topic does not. A driver is a driver however your points make to seem that ALL commercial drivers are like this, while maybe only a few passenger vehicle drivers are.

    As a commercial driver, and and ex volunteer firefighter,(in a a somewhat rural area, not a large city), I can say that all emergency service lights have gotten to the point where they are so bright, especially at nite, in the rain and other inclement weather, you can’t see anything ahead. U cannot see fire trucks, or police cars, or ambulances. OR the personel. All u see is 4 million led strobe lights flashing away at 6 billion candle power, and 10 sets of super bright white headlights flipping away on the wig wags. I don’t see any reason why there can’t be a ‘parked’ setting that dims down the brightness by 1/3, or even better 1/2. Shut the headlight wig wags off. I can understand the see and be seen theory, but passing traffic, through a emergency scene needs to be able to see where theyre going as well. I have been through scenes where I can’t even tell traffic is being diverted. I was parked for almost 10 minutes once until a police officer came up and asked why I was holding up traffic. The firefighter directing traffic was positioned in the front corner of the fire truck and without vehicles ahead of me to follow, I just thought the road was closed. Could not see even a glimpse of him. The policeman could not see him either, and had him reposition further back where he could be seen.

  3. I have always felt that lighting needs to be purposeful. That is to say it should indicate what it’s intent is. In response mode that is pretty easy, get out of the way ! When blocking a lane it is very different. The lighting must say here I am, I am an emergency vehicle and you must slow, stop, go around or whatever. I agree with the high, slow flashing idea. Couple that with an arrow board and you have purposeful lights. Add some cones and better yet a police officer directing traffic and wow, a much safer work area. Dazzling high output lights, in my opinion, are attention grabbers but once drivers recognize what they are approaching, they need direction they can see and understand. That is what makes a scene safer. Blinding barrages of emergency light flashiness? Not so much.

  4. I agree that high and slow may be a good alternative, and that too many drivers are not driving appropriately. It would be good for all if there was more enforcement and stiffer penalties for distracted, impaired and reckless/careless driving.

    One thing I noticed recently was a newer school bus with LED lighting that had a very fast flash rate, much like we see on emergency vehicle light bars.

  5. As a really old guy, I remember when one of our newly delivered ambulances came with our fleet’s first LED warning lights. I was the first to drive that vehicle Code 3 and we were on duty for a weekend in the mountains. Going around curvy roads with hills around us, the high intensity of the strobes flashed back off the sides of the hills and blinded us (God knows what it did to drivers of other vehicles who were getting the light full on). We called the manufacturer and found out there was a switch on the control box that lowered the intensity of the lights which we used and it solved our problems. LED lights can be exceptionally bright (my little Fenix flashlight puts out 10,000 lumens!), and can blind other drivers which is exactly the opposite of what we’re trying to achieve. We want to make the movement of our vehicles through traffic and on scene safer, and using super bright flashing lights of any type may be self-defeating.

  6. We have used amber lighting in both upper C & D quadrants for over 20 years with no apparent ill effects. First they were all halogen & now all LEDs. I must agree, the issue is not in the Fire Service rather with the motoring public who are too distracted, too impaired or just too what-ever. No document be it NFPA, OSHA or State Regulation will force the driving public to be better drivers. Please let’s not have some “knee-jerk” reaction that may or may not have any impact.

  7. Mr. Adams, you might find an article titled “Situational Based Emergency Lighting Systems Aid Officer Safety On The Road” (in the most recent issue of Law Enforcement Technology) not only interesting but highly relevant to your preference for “research in the form of data and testing.”

    The article is as quick a read as yours, and is available on-line at:

  8. too many and too bright – I was a State Trooper and in 1970s we had ONE beacon ray on the roof and we never got hit parked in the middle of the road or on the side. The more lights they added the more cars got hit. Then we put amber lights on the rear of the light bar and shut down the rotating lights when parked – No cars ever got hit doing that. The ones who left everything on got hit? So they added more lights – people drive where they look and when you set up a carnival the will drive into it….

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