BY BILL ADAMS
It is improbable to impossible for an apparatus purchasing committee (APC) to write a purchasing specification for a custom cab and chassis without interfacing with one of the manufacturers that builds them.
When doing so, APCs usually follow a preferred manufacturer’s specification verbiage verbatim for the quantity, type, and location of a cab’s headlights. Maybe they shouldn’t. They don’t have to.
Because of the correlation between headlight and directional light locations, this article continues the lighting discussion (“Apparatus Purchasing: Front Directional Lights”, Fire Apparatus & Emergency Equipment, March 2019) on custom cabs. Although headlights appear to be an innocuous topic, valid questions and concerns have been raised about them. How do they work? What determines their location? Who determines their location? Why are they so bright? How should they be aligned? Some queries are addressed herein.
The Electric Vehicle Company of Hartford, Connecticut, introduced the first electric headlamp in 1898. In the early 1920s, Massachusetts was one of the first states to require headlamps on all motor vehicles. Major innovations since then include sealed-beam headlights in the late 1930s, halogen lamps in the 1960s, and high-intensity discharge (HID) lamps in the early 1990s, followed shortly thereafter by light emitting diode (LED) technology. HID lamps never really caught on. Because purchasers have become enamored with them and many OEMs offer them as standard equipment, only LEDs are discussed herein. However, it must be pointed out that some vendors may offer halogen headlights as a default standard with an LED option. That may be a cost consideration rather than a performance criterion. Halogen headlights are still effective, legal, and desirable by some purchasers.
Sam Massa is the founder, president, and chief technologist of HiViz LED Lighting, the manufacturer behind the FireTech Brand. The HiViz Web site states that its product line includes LED scene lighting ranging from full-width low-profile brow lights to headlights and everything else in between. HiViz does not market warning lights for the public safety industry.
Massa, who is also a volunteer firefighter and an emergency medical technician, authored a very understandable white paper for the Fire Apparatus Manufacturers’ Association (FAMA) titled, “Fire Apparatus Headlights: A Lot to Know” (https://www.fama.org/forum_articles/fire-apparatus-headlights-lot-know/). He agreed to be interviewed for this article and to speak in nontechnical terms. Three of his white paper comments worth pondering are paraphrased below:
- Some million-dollar fire apparatus today still use 1960s-era headlight designs.
- What most firefighters would like changed on a rig’s lighting is the headlights.
- Some apparatus committees specify $40,000 worth of scene lights and $200 worth of archaic glass and halogen headlights.
I consider this Massa comment to be significant, hence, it is verbatim: “A properly designed set of headlights for use on roadways must be designed to comply with an extremely precise set of photometric requirements spelled out in both SAE standards as well as FMVSS108. This set of photometric requirements ensures light from the headlights is sufficiently bright to illuminate the roadway, but more importantly ensures that light from the headlight of your vehicle does not present a hazard to other vehicles sharing the roadway. Just because the truck says ‘FIRE DEPARTMENT’ on it does not exempt it from the law.”
SAE AND DOT
The Society of Automotive Engineers (SAE) is not a regulatory body. According to Massa, “It has no authority to approve headlights or anything else. And, there is no such thing as DOT-approved headlamps, because the Department of Transportation (DOT) does not approve vehicle equipment. The industry has a self-certification system where the maker of a regulated type of vehicle equipment such as a headlamp certifies (basically promises) that the equipment meets the legal requirements. In the case of a headlamp, the lens marking ‘DOT’ counts as the certification. A headlight marked ‘DOT SAE VOR HL P 16’ identifies the test standard, the cutoff angle and how to aim it, the source type, and the year it was certified.” Low-beam lamps are “visually optically aimed” right and are marked VOR or left VOL. High-beam lamps are nondirectional “visually optically aimed” and are marked VO. P designates parking. While the specific markings vary by brand and configuration, a headlight lacking this data does not conform with the requirements in Federal Motor Vehicle Safety Standard (FMVSS) 108 and is not legal for use on roadways in North America.
SHAPES, CHIPS, AND OPTICS
There are various size round and rectangular shaped headlight fixtures (photos 1 and 2). Small-diameter round fixtures are common on buses and stylistic fire chassis similar to Rosenbauer’s Avenger series (photo 3).
The materials used and detailed and possibly proprietary methods of construction are left for the individual headlight and chassis manufacturers to elaborate on, praise, promote, or denigrate—as they see fit. Different than a halogen lamp’s filament, which can burn out, an LED chip is a very small piece of silicone that emits visible light (it glows) when voltage is applied to it or across it. Again, confer with the light manufacturers for techno terms such as photons, electrons, light emitting diodes, and semiconducting material. Most firefighters only care if a headlight is bright enough or too bright.
When asked if the physical size of an LED chip makes a headlight brighter, Massa replies, “Chip size is irrelevant. Effectively, LEDs with a high wattage rating combined with the amount of power sent across the chip determines brightness. All the light (brightness) in the world is useless, if not dangerous, if not properly directed by the optics. Its ALL about where the light falls—not how bright it is.” The optics either concentrate or diffuse the light generated by the chip.
His FAMA white paper notes headlights must meet an “extremely precise set of photometric requirements spelled out in both SAE standards as well as FMVSS108.” Multiple locations called test points or zones are where light measurements are taken. Some simple explanations of the testing follow.
- Some test points have requirements for both maximum and minimum levels of light.
- The locations and values of the test points and zones are specific to the function.
- The level of light from a headlight is measured at certain degrees up, down, to the left, and to the right of dead center.
- A high beam puts its highest intensity straight ahead.
- A low beam puts its highest intensity slightly downward and rightward from dead center.
- There are “seeing light” test points to the right and upward of dead center to allow roadside and overhead signs to be adequately illuminated.
- There are “seeing-light” test points clustered in the region just to the right of center and just below horizontal for maximum down-the-road seeing on your own side of the road.
- There are “glare light” test points to ensure oncoming drivers are not blinded.
In layman’s terms, headlights should simultaneously put light where it’s needed and keep it away from where it’s harmful. Too much light in certain areas is just as dangerous as not enough. And, the optics are what do it. Purchasers should bear in mind that headlights are tested in a lab. The testing and self-certification are similar to what the warning light manufacturers do when testing their products to be in compliance with National Fire Protection Association (NFPA) 1901, Standard for Automotive Fire Apparatus. The light manufacturers test the products themselves and certify they are compliant—when properly installed by the apparatus manufacturer. The same applies to headlights. NFPA 1901 allows purchasers to require testing of warning lights be completed after installation, but that seldom, if ever, happens. I know of no procedures, mandates, or regulations for testing headlights after installation or of any test requirements by the DOT after delivery. Both the warning light and headlight manufacturers are at the mercy of the apparatus manufacturers to install their products “per code.”
End users shouldn’t tie themselves in knots trying to understand the technical data advertised or supplied by light manufacturers. I find it confusing. I believe the headlight manufacturers must complete a “photometric data plot map” showing compliance with DOT testing requirements, but I doubt comparing them would be of use in the field when purchasers evaluate headlamps.
One manufacturer promotes a low beam producing 1,900 lumens with an 18,000-candela output. In reality, it only has 575 effective lumens. Massa says, “Drivers don’t see lumens, but they do see how light is distributed.” Lumens is the overall light output by the LED regardless of its intensity. Lux is the amount of lumens on a particular surface at a given distance from the light. Candela is the intensity of the light. Nick Irwin, vice president of manufacturing for HiViz and the technical innovator behind many of its products, offers a simple explanation. “Lumens is like the volume of water coming out of a fire hose. Candela is like the nozzle pressure—you’re not changing the flow; you’re increasing the intensity (fog pattern or solid stream). And, lux is how much water is hitting the target you’re aiming at.”
Purchasers should have no reason not to believe that a headlight meets DOT requirements. However, I question whether headlights should—at the least—be aligned (aimed) after delivery of a new rig and it is loaded and “settles.” Does the fire department have an obligation or a responsibility to align apparatus headlights after a rig has been in service? How often should it be done? Do state-mandated vehicle safety inspections for commercial vehicles require it?
Glare, also defined as brightness, brilliance, and shine, is an ambiguous term. To nighttime drivers, glare is an undesired result of light being shined into the eyes to the point that vision may be impaired. Regardless of DOT-required “compliance” with glare testing, I believe personal observation and opinion determine the level of glare acceptable in the field. In the early 1920s, the Illuminating Engineering Society (IES) developed a standard that required a headlight beam to produce specific amounts of light aimed in specific directions. That standard was followed and adopted by some individual states. The federal government took over all motor vehicle standards in 1968 with the adoption of FMVSS108. It legally superseded all state regulations.
It appears that the 1921 IES criteria was the first attempt at reducing or regulating headlight glare. A 2012 Boston Globe article attributed headlight glare to the newer (at the time) halogen light technology. NFPA 1901 states that warning lights should be placed to maintain the “maximum possible separation from the headlights.” The NFPA has not addressed directional light proximity to headlights, perhaps believing directional lights and headlights are the domain of FMVSS108 and the chassis manufacturers.
With a general concern that today’s LED warning lights on fire apparatus may be “too bright” when in the blocking-the-right-of-way mode, perhaps headlight glare is something that should be considered by a purchasing committee. Are today’s LED headlights “too bright”? Massa says, “If a headlight actually meets the photometric requirements of FMVSS108, it should not produce glare in the eyes of oncoming traffic.” Perhaps headlight glare is a subjective determination and not one substantiated by hard facts. Because almost all custom cab and chassis manufacturers are willing to locate headlights in multiple locations indicates that some fire departments or apparatus manufacturers have already individually or regionally addressed the issue. Their reasoning should be shared.
Front bumpers on custom apparatus have valuable real estate most fire departments want to use. When doing so, they may be inadvertently obscuring or outright blocking headlights as well as warning and directional lights. The flat surface between the cab fascia and bumper is a deck usually of aluminum treadplate that’s also called an apron and sometimes a gravel shield. It’s about 30 inches from ground level depending on the tires, suspension, and chassis design features such as a low-profile cab or an all-wheel-drive chassis. Purchasers must be cognizant of the angles tilt cabs require in the raised position. Some accessories have been mounted on bumper compartment covers that must be tilted to raise the cab. Ditto for equipment stored upright such as fire extinguishers.
A mechanical siren is 10½ inches tall, the eagles on some decorative bells are 18 inches high, and some swiveling suction elbows can be up to 18 inches from the deck. At recent trade shows, informal measurements taken from the deck to the centerline of the headlights on a dozen custom cabs ranged from 12 to 22 inches.
Obscuring headlights is a concern. There may also be an upward glare at night or in inclement weather from headlight beams reflecting off a chromed suction elbow, bell, or siren. Glare isn’t easily perceptible when you are sitting in the cab at a trade show.
Despite headlights having to comply with the photometric requirements spelled out in both SAE standards as well as FMVSS108, most apparatus manufacturers and headlight manufacturers do not reference them. In-the-field vendors normally say they meet FMVSS108 and DOT and are done with it. “Why confuse the general populace?” must be the mantra. Besides, more than likely, many purchasers couldn’t decipher the technical statistics, charts, and graphs. They can, however, tell the difference if a headlight drowns out a warning or directional light. They can also tell how well the apparatus driver can see down the road when the headlight is in one location or another. Has anyone done any testing to justify specifying a headlight location? Although subjective, it could be the reasons OEMs have so many varied headlight locations. Ask.
Some apparatus manufacturers offer both LED and halogen headlights from multiple manufacturers. Massa states, “It is not true that headlamps using new LED or HID technology are necessarily better than headlamps using older halogen technology. It’s often true because the newer technology eliminates certain kinds of performance constraints that existed with the older technology. There are some excellent halogen headlamps, and there are some lousy LED and HID headlamps. However, while any headlamp certified to meet DOT criteria may be legally equivalent to any other headlamp certified to meet DOT criteria, that does not mean it is all functionally equivalent. That is very important and a good reason to purchase from a reputable manufacturer.” He ends with, “There are a variety of options to choose from when specifying headlights on a fire apparatus. Some are very low cost, some more expensive, but nevertheless, it is important to keep in mind that the headlight selection you make for your apparatus can have a tremendous impact on your ability to answer the call safely at night. Many headlight manufacturers are willing to offer demo sets or have sales teams who can sit down with your committee to explain the differences in headlight options and types.”
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.