Amber warning lights are always a concern. What type of warning are you providing? Is it adequate? Will your lighting interfere with the drivers of the vehicles trying to pass around your truck? There are several solutions, but the main concerns are: providing the right warning, not interfering with passing traffic, keeping the traffic moving around your truck safely and not increasing maintenance costs.
Solution-seeking maintenance directors must be aware of how the product provides warning and how the light disperses from the lighting fixture. The automotive industry’s Society of Automotive Engineers has developed a great procedure to test warning light fixtures. They have classified the lights into three categories for light intensity: SAE Class I, the brightest; Class II, the middle intensity; and Class III, the dimmest. There are several other requirements established by SAE for warning lights, which pertain to moisture, dust, vibration, voltage and electronic standard. We want to address the light output and direction of that light for this article. Note that no matter what the light source—LED, halogen, incandescent or strobe—the test is the same.
What you want to address is how the light is warning oncoming traffic. This is the base of what SAE’s light intensity classification provides. This standard addresses the intensity of the light and the spread of the light coming from the warning device. With this knowledge you are able to assure yourself that you are sending out a warning signal that is providing the proper warning. The standard calls out test measurements from the light source at five different angles, at a distance of 100 feet. These angles are: horizontal/vertical point, which is the center point of the lens, both vertical and horizontal; 2.5 degrees up from that HV point; five degrees up from that HV point; 2.5 degrees down from that HV point and five degrees down from that HV point. These measurements are used for all three intensities of the SAE classifications: Class I, Class II and Class III. In interpreting these intensity measurements, it is clear that the more light you have, the stronger the signal to the oncoming traffic.
Intensity tells us how far we are reaching out with the light. The angles provide us the location of where we are sending the light and its impact to the oncoming vehicles. The intensity is measured in candela. This dispersion is very narrow, with only a 10-degree spread at the light. A majority of the light is at the HV point. For a Class I amber light the test point measurements are: HV 8100 candela; for the 2.5 degrees up and down, only 4050 candela; and for the five degrees up and down, 900 candela.
This is very interesting. As you can see, the 2.5 degrees up and down is half of the value of the HV. There is even a greater reduction in intensity at the five-degree test points, with about 12 percent of the HV test value. The value in this requirement is that, at a distance the light provides a bright warning. But as you approach the vehicle with the warning light, the flash appears to get dimmer. This is because you are passing through the bright light spread provided by the HV point and entering into the 2.5- and eventually the five degree test points. With the light mounted on the vehicle above or below the average passenger car windshield, the oncoming driver will get out of the warning light’s brightest intensity points and not lose sight of the perimeter of the vehicle with the warning light.
You must also take into consideration the speed of the vehicle to which the warning light is attached. A general rule of thumb is to compare the vehicle’s function. If the vehicle is not moving in traffic but parked alongside the roadway, a Class III light may be adequate. For vehicles moving with the traffic but not at the speed of the traffic, a Class II may be adequate. On vehicles moving at the speed of the traffic, a Class I should be used. The Class I light is, in most cases, the default lamp of choice. Many fleets and some states are requiring a Class I light be used on all road construction vehicles. Knowing the value in having a SAE-approved warning light that meets the light spread and intensity required by the standard is important. It is not the type of LED, the number of LEDs or any other marketing-made specification that matters. The key question is, does the light meet the standard for light output in each of the five angles?
Fleet directors assured of the light’s ability to meet SAE standards can now focus on durability and ease of installation.
Durability is having a light that is suited to the vehicle’s application. Minimum requirements are: how the circuit board and lamp compounds are protected from moisture, vibration, shock, voltage surges and current draw; and other product features that meet the fleet’s requirements.
Regarding the installation: Ask yourself, does it require extra effort or special need to install? Is it adaptable to current installations? Is the size suitable for the vehicle on which it is being installed? Is it user friendly? Is special training required to install it? Does it require special training to operate?
Information provided by Star Lighting Products Inc., Cleveland, Ohio (800) 392-3552