Apparatus Purchasing: Front Directional Lights
BY BILL ADAMS
Are forward-facing directional lights on custom cabs effective when responding at night? It’s doubtful it has been given serious thought. Lacking testing and substantiation, any answer to the question merely reflects individual observation and personal perception of what is, or is not, effective.
Personal opinions and viewpoints can’t be proven right or wrong. However, some are worth discussing. I believe the effectiveness of directional lights at night can be negated by headlight glare. And when flashing headlights are used as an optical warning light, directionals can be rendered useless. I have no scientific proof. Using a search engine for “fire trucks responding at night” generated more than six million hits. Searching for “fire trucks at night” generated more than 93 million hits. Reviewing many of the images and videos supports but doesn’t factually prove my viewpoint. I also believe the various types of directional lights (aka turn signals, directionals, and blinkers) and their physical locations can affect their effectiveness.
Custom cab and chassis manufacturers (OEMs) have standard types and sizes of turn signals, headlights, and lower-level warning lights. Most offer optional types and sizes as well as locations for them. It is unknown if vendors voluntarily inform prospective purchasers of them. They should. Some apparatus purchasing committees (APCs) give little thought to directional lights when writing purchasing specifications. Perhaps they should too. Many rely on the verbiage preferred OEMs suggest. The easy way out, possibly less expensive, isn’t necessarily the best way. I wonder what reasons end users have for purchasing the various light configurations shown in the accompanying photos.
A common arrangement on traditionally styled cabs is a quad-light configuration consisting of dual headlights, a directional, and a warning light on each side. Generic purchasing specifications can be as vague as, “A turn signal and warning light shall be installed above dual headlights on each side.” That’s a lousy specification. It could be more detailed—if it matters. Types, sizes, and manufacturers of lights and lamps and their locations could be specified—again, if it matters. Not all OEMs provide a single fixture to house the lights (photos 1-4). Multiple bezels allow flexibility in mounting locations.
If OEMs offer multiple locations for directional lights because one works “better” than another, perhaps they should inform the fire service. If fire departments specify directional light locations because of proven performance, they also could share their knowledge.
DECIPHERING FEDERAL STANDARDS
By law, OEMs have to meet applicable federal standards when installing chassis lighting for over-the-road use. Commentators, pundits, industry experts, consultants, and OEMs often refer to the myriad, what I call the “alphabet,” agencies when discussing chassis lighting. The Truck-Lite Company of Falconer, New York, has a link at https://bit.ly/2DHOAfA that gives a basic heads up to the federal regulatory agencies for commercial vehicle lighting.
Paraphrasing it, the Department of Transportation (DOT) is the governmental umbrella for everything dealing with transportation, including the National Highway Traffic Safety Administration (NHTSA), which regulates lighting requirements for all new road vehicles. NHTSA regulations take precedence over state regulations. Fire trucks are commercial vehicles that must comply with NHTSA criteria.
Elaborating on the alphabet agencies, NHTSA promulgates Federal Motor Vehicle Safety Standard No. 108 (FMVSS 108), which is the federal code (law) regulating lighting and performance requirements, including the numbers and locations of lights on commercial vehicles. CMVSS 108 is the Canadian version. According to the Government Publishing Office (GPO), at https://bit.ly/2R0s9H1, the Code of Federal Regulations (CFR) is “… the codification of the general and permanent rules published in the Federal Register by the departments and agencies of the Federal Government.” CFR Title 49—Transportation is the section dealing with chassis lighting. Equally confusing, the Federal Motor Carrier Safety Administration (FMCSA) issues the Federal Motor Carrier Safety Regulations (FMCSRs), which are the standards used by most states when inspecting commercial vehicles.
The nine domestic custom cab and chassis manufacturers commonly refer to one or several of the above-mentioned alphabet agencies. Smart ones just say they comply with FMVSS 108 and let it go at that. Purchasing specification writers don’t have to specify federal standards that are required by law. OEMs must comply with federal regulations whether or not a purchaser specifies it. The OEMs agree that federal regulations require front turn signals to be between 15 inches and 83 inches from ground level, amber in color, and located one on each side of the vertical centerline at the same height and as far apart as practicable.
Perhaps the reason some purchasers request other-than-standard locations for forward-facing directional lights is because factory-standard locations are not working well. Not working well could be justification for additional (auxiliary) forward-facing directionals. OEMs have varying answers on whether a second set of forward-facing directional lights is legal to install and, if so, if they have to be compliant with DOT regulations. Several vendors were asked if they have added secondary turn signals, in particular on West Coast mirrors (photos 1 and 2). Some say they have. Some say they legally can’t. Some say they can as long as they meet federal requirements. There is no intent to disparage or denigrate any vendor that has a different interpretation of a DOT standard. Because their answers reflect viewpoints and interpretations, their comments are not published. Finding correct answers may be as difficult as proving headlight glare obscures directional lights.
INTERPRETING THE STANDARDS
Because it is not fair to compare one OEM’s opinion with another, I asked an outside source for an interpretation of the standard. Daniel J. Stern, a freelance vehicle lighting consultant based in Vancouver, British Columbia, is known worldwide for his expertise in the field of lighting, light-signaling devices, and systems on motor vehicles (https://bit.ly/2MC80Fv). He is a resource for this article and has been kind enough to explain some regulatory criteria in language understandable to the rank-and-file fire service. He says sometimes regulations are “… written in English words, but they aren’t really in English—often a plain-English reading will mislead the reader.”
I interpret the DOT standard as saying there can be only one set of forward-facing directional lights and asked Stern the question: “If a second set of directional lights is allowed, do they have to follow DOT regulations?” Stern states, “A basic principle of North American vehicle regulations is that anything not explicitly prohibited is permitted, provided it doesn’t impair the effectiveness of any mandatory device, function, or design feature. So, someone saying ‘the regulation doesn’t say I can have auxiliary lights, so that means they’re illegal’ is wrong. It’s not that there ‘may only be’ one directional light, it’s that there ‘must be’ one directional light on each side. That is the requirement. Additional (auxiliary, supplemental) directional lights are permitted as long as they do not impair the effectiveness of any required item or design feature. ‘Impair the effectiveness’ can mean anything from physically blocking a required light to visually drowning it out with a brighter light nearby, to confusing its message with wrong-color auxiliary lights. Other than that, any number of auxiliary turn signals is legal. A manufacturer that claims it’s legally prevented from putting auxiliary front turn signals is mistaken. It should consult someone who knows what the regulations mean.” I find Stern’s comment about “impairing the effectiveness of a light” very interesting. I wonder if a flashing headlight legally renders a directional light ineffective?
TURN SIGNAL LAMP MARKINGS
There can be a misconception that turn signal lamps are required to have identification markings. Some Web sites allude to the Society of American Engineers (SAE) having various categories of markings. Stern says, “SAE markings are not mandatory. In the United States, there are no mandatory markings on any lamps except headlamps.” He continues, “While SAE recognizes six different categories of turn signal lights I, I3, I4, I5, I6, and I7 (“I” is for ‘Indicator’), SAE standards themselves do not carry force of law. It probably isn’t helpful discussing identification numbers given the mismatch between SAE and the regulation itself. Federal Motor Vehicle Safety Standard 108, which does carry force of law, contains the following four classifications:
- A front turn signal that is less than 100 mm from the nearest lit edge of a low beam and/or less than 60 mm from the nearest lit edge of a fog lamp or auxiliary low beam.
- A front turn signal that is 75 to 100 mm from the nearest lit edge of a fog lamp or auxiliary low beam.
- A front turn signal that is 60 to 74 mm from the nearest lit edge of a fog lamp or auxiliary low beam.
- A front turn signal that is more than 100 mm from the nearest lit edge of a low beam, fog lamp, or auxiliary low beam.”
Because apparatus manufacturers provide multiple locations for directional lights and because of the propensity of some purchasers to specify lighting by a preferred supplier and model number, both should be aware of what applicable regulations mean and require. Stern cautions, “Intensity requirements are 2.5 times higher for turn signals located within 100 mm to a low beam or 60 mm to a fog lamp or an auxiliary low beam. You can use a high-intensity turn signal no matter where it’s placed, but you must use a high-intensity turn signal if it’s within the specified distances, or the vehicle will be noncompliant, and the turn signal won’t necessarily be adequately conspicuous.” (Underlining is mine for emphasis.)
Make sure what you are specifying and what a manufacturer is proposing are compliant. One could presuppose a manufacturer will provide the proper lamp on its own even if it is not in a department’s purchasing specification. But then again, I maintain that if something is not in writing in a purchasing specification, it does not exist. Inquire. Reputable apparatus vendors should know. Additionally, domestic manufacturers of quality lighting products for heavy-duty vehicles in North America have knowledgeable engineers on staff who can correctly and dependably answer compliance and application questions. Stern notes that purchasers should keep in mind the difference between price (paid upfront) and cost (paid out over time) and to buy good lights from a reputable maker.
SIGNAL LIGHT EVOLUTION
The December 1985 issue of Popular Mechanics states that the Protex Safety Signal Company introduced flashing turn signals in 1920. Edgar A. Walz Jr. patented the first modern turn signal in 1925 and tried to market it to major car manufacturers. It is unknown when the fire apparatus industry adopted them; however, apparatus were delivered without them well into the 1950s. According to Stern, front directional lights were not required on commercial vehicles (including fire trucks) until 1968 when FMVSS 108 took effect. Prior to 1968, some states had their own requirements.
In the 1980s and 1990s, many custom chassis manufacturers including Duplex, Spartan, Hendrickson, Pemfab, Grumman, Crown, and Hahn featured “guide arrow” directional lights similar to the one in photo 16. Guide arrows, whose fixtures were arrow-shaped, were usually mounted between the headlights and the lower part of the windshields well away from warning and headlights. I believe the location made the directional more visible at night. But, it couldn’t be proven then and probably can’t be today.
The current quad-style light configuration with integral directionals is probably easier to install and less expensive. The downside is the directional might be compromised by the headlights. It is unknown why some manufacturers today have begun separating front fascia lighting.
I asked an apparatus manufacturer that does not build a cab and chassis and an apparatus dealer for input about directional light locations and types. Joe Messmer, owner of Summit Fire Apparatus, says he prefers a four-inch by six-inch LED amber directional light separate from the quad-light cluster “because it makes it more noticeable. We really think having them separate makes them more visible. Having them in the cluster is like we are meeting the requirement, but sometimes we all have to think beyond just meeting the requirements.” He adds that his customers “prefer turn signal lights as we recommend them, but sometimes the additional cost keeps them from doing it.” One warning light manufacturer offers two models of front turn signal lights. One model features six-by-four-, nine-by-seven-, and four-by-three-inch sizes. Another features six-by-four- and nine-by-seven-inch sizes. Most light manufacturers’ literature does not mention the lights’ specifics, usually just stating they’re available with incandescent, halogen, and LED lamps.
Mark Aswad, owner of Firehouse Apparatus, Inc., a 4 Guys and HME-Ahrens Fox dealer, adds, “I prefer to suggest to my customers to locate turn signals higher above emergency warning lights. By having the directional positioned by itself up higher, oncoming traffic will recognize it quicker. Common requests we get from customers are to make sure we utilize good quality LED lights. Sequential-style flashing LED lights work well, but as long as they stand alone and are LED, they appear to fit the bill.”
TEST AND VERIFY
It would be beneficial to test the effectiveness of directional lights—at night with headlights and all warning lights activated. Perhaps it could be something as simple as determining if a directional light is visible at a certain distance from the apparatus. Another possibility could be requiring that directional light “intensity” (however that is determined) be greater than other lighting mounted within a certain distance from the directional. Lighting manufacturers will probably explain test results using techno terms such as goniometers, integrating photometers, candela-seconds/minute, optical power requirements, and hemispherical light sensors. OEMs, whether they be apparatus or light manufacturers, could make life simple by informing fire departments in understandable terms what directional lights work best and the best places to locate them. It would help.
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.