In an effort to reduce accidents involving large commercial trucks and other vehicles, the application of DOT C2 red and white (silver) reflective tape to trucks was mandated by federal law in 1992. This was a very important step forward in preventing accidents, injuries, and fatalities from collisions between the large trucks and smaller vehicles. Although the red and white (silver) tape is visible in the daytime, its main purpose is to provide increased safety and visibility at night when reflecting back to an oncoming car’s headlights. This increase in visibility allows smaller vehicles more time to react and avoid a potential accident.
To be clear, tractor trailers present a particular danger to smaller cars for two main reasons. First, they are large and relatively immovable, which means that an impact is much more severe than with an object with less mass. Impacting a truck with a small car would be like hitting a brick wall in that the car would absorb almost all of the impact energy. Compare this to hitting a dumpster with your car where the container absorbs roughly the same amount of impact as the car. Secondly, because of their distance off of the road surface, an automobile can easily go under a truck and either sheer off the top portion of the car, or get trapped underneath. So seeing the truck, and stopping in time, is critical.
Shown below is a chart from the MUTCD that outlines how many feet are needed to react and stop a vehicle. It demonstrates the importance of visibility as a component of accident reductions. The farther away a driver can see an object, the more distance they have to stop. And when it comes to large trucks, seeing them from the greatest distance possible is paramount.
Effectiveness of Properly Applied and Cared For DOT C2 Tape – Before we discuss mistakes made in applying and maintaining DOT C2 tape, let’s look at how effective it can be when it is fresh and properly applied. An extensive study was completed by the NHTSA back in 2001 regarding DOT tape. This was 8 years after the law mandating it went into effect. The object of the study was to determine how effective the tape was at preventing accidents and fatalities. The study is older, however it is very relevant since it was done within a decade of the period in which trucks were not required to be marked with reflective tape. It is based on an analysis of 10,959 crash cases involving large trucks. Below is an excerpt from the abstract / summary section of the report.
Quote – The tape is quite effective. It reduced side and rear impacts into trailers, in dark conditions (including “dark- not-lighted,” “dark-lighted,” “dawn,” and “dusk”) by 29 percent. In “dark-not-lighted” conditions, the tape reduced side and rear impact crashes by 41 percent. Tape is especially effective in reducing injury crashes. In dark conditions, it reduced side and rear impacts that resulted in fatalities or injuries to drivers of any vehicle by 44 percent. – End Quote
|Conspicuity – To clearly understand this issue, it is important to remember why trucks are marked with bright alternating colored reflective tape to begin with. To be clear, the object of marking a truck is “Conspicuity”, which is defined as the property of being clearly discernible. The state or quality of being clear or bright; brightness; conspicuousness. In other words, conspicuity goes beyond just being able to see an object. For example, in daylight or with our car headlights, we see a variety of objects all around us or ahead of us. But just because something can be seen, does not necessarily make it conspicuous. To be conspicuous, a particular object must be clearly discernible when compared to other objects around it. Just as camouflage makes an object blend in, conspicuity makes it stand out. Bright, contrasting colors are considered to be conspicuous, especially when there is no competition for visibility. At night, to be seen, these colors would need to also be retro reflective, which means the colors reflect back to the source of light.|
But reflectivity is not necessarily enough at night to make something conspicuous. There must also be contrast of different colors, so that the object you are trying to make conspicuous stands out from other lights or reflective surfaces. An example would be traveling down a city street at night. As you observed what was in front of your vehicle, you would see many white lights from other car headlights, street lights, and street signs. So one more section of white reflective tape on a truck would not necessarily get your attention. But if that section of tape alternated in color from red to white, that would get your attention, because it is different from everything else you are seeing. In other words, your eyes see it, your mind registers it as different from everything else you are seeing, and you take action to avoid it if necessary.
The purpose of this article is to call to attention circumstances that can prevent DOT C2 reflective truck tape from accomplishing its intended purpose. Or rather, mistakes that can be made by trucking companies or drivers that can lead to unnecessary accidents, injuries, or fatalities. Some of these involve placement, and some relate to the age, condition, or type of tape. By understanding how these issues affect performance and visibility, they can be avoided so that all drivers are safer.
Old, Dirty or Delaminated Tape – tape that is delaminated or old and hazy reflects less than new tape. A tape that reflects 600 candela’s when new, can slip to 400 candelas just from age. Dirt and grime on the tape further reduce its reflectivity. Delamination is also an issue with air backed prismatic tapes that have been impacted. Once a tape begins to come apart, water, dirt, and grime find their way behind the tape, and when this happens, the tape performs poorly in those areas. It may still reflect, however, the maximum sight distance for the film will diminish greatly, depending on how old, hazy, or delaminated the tape is. And with only part of the tape reflecting, it can confuse a driver. Versus a long, continuous run of bright alternating red and white reflective. The image of the truck below is a perfect example of dirty tape that reflects at almost zero candelas and provide almost zero protection. Also note that on this truck the tape that is applied is old, and applied so high, most cars headlights will not hit it. To make matters worse, this is a tanker truck carrying hazardous materials, making it one of the most dangerous classes of vehicles on the road.
Tape Placed Too High on a Truck – automobile headlights in standard driving mode purposefully shine low to keep from blinding other drivers. Because of this, DOT tape needs to be placed as low as possible. And even when placed low, drivers often only get full reflectivity from far back, since their headlights have widened over distance. (see diagram) Up close, lights almost always hit under the tape, which produces very little return of light. Because of this phenomenon, the opportunity to see the tape is normally when a car is out at least 300 feet away or further. So if tape is applied too high, say on the side of a tanker, it is possible that approaching drivers would never see the tape reflect at all. Low as possible placement is critical to prevent collisions. Note – there are areas on the truck that are lower, where additional DOT tape can be installed, this would greatly increase visibility for lower passenger and sports cars.
Note – As an example, in the picture below, tape has been applied to the machine that hangs off the back of the truck. If you look closely, you will notice how it is brighter than the tape on the side of the truck bed. This is because it is lower, and more in the line of the headlights of a car. So as previously stated, the lower the tape, the better it can be seen by approaching cars. And when cars and other trucks see it, accidents are avoided. Also on the truck below, notice that there are other places that tape could be placed. Below the drivers door, and on the frame of the truck below the existing bed tape. These applications would make the truck much safer at night. And the cost would be less than $20.
Tape Placed at an Angle Versus a Proper Vertical Application – DOT C2 tape reflects best when it is perpendicular to a light source. A perfect perpendicular beam would be considered a zero entrance angle and would produce the highest return of light to the source. When a tape is angled to a light source, it performs less efficiently. It will still reflect, but at lower percentages. For example, a DOT C2 tape on a tractor trailer rig that is placed at a 30 degree angle, will lose about 20% in reflectivity for the red, and 40% for the white portion of the tape. It will still reflect, and may still appear bright, but from a long distance, it will be diminished in brightness. So if it gets an approaching drivers attention at 1000 feet when installed properly, this may reduce to 700 feet when installed improperly. This difference may not seem significant, but when you consider that it takes about 820 feet for a car traveling 75 miles per hour to stop, it can be catastrophic. If you combine an improper application with a dirty or weathered tape, conspicuity is reduced even further.
Below is an excerpt from a study that was done by SAE International, analyzing the performance of reflective tape at different entrance angles.
|From the current study, it was determined that the entrance angle and the observation angle affected the performance of all of the retroreflective tapes, with lower performance at higher entrance angles and/or observation angles. It was also determined that the white retroreflective tape had higher performance than the red retroreflective tape for every tape type tested. Finally, it was determined that the performance of the tape decreased when measured through the windshield of the vehicle, versus from outside of the vehicle.|
Counterfeit DOT Tape that is not compliant with NHTSA / FMCSA Requirements – Online marketplaces sell DOT made in other countries that is often quite a bit cheaper than tapes made in the USA. This can present a problem in that many of these tapes are not truly DOT C2 compliant. They are counterfeit or knock off tapes. Often these tapes are not bright enough to comply with photometric requirements, which means that even when brand new, the tapes do not reflect bright enough to provide conspicuity. In other words, non compliant tape that just says DOT C2 tape may look official, but it does not perform like it should. What this can mean is that a car approaching a truck outfitted with counterfeit tape may not see the tape in time to avoid an accident. Picture what would happen if a car is approaching a stalled truck that is partially blocking a highway at a speed of 70 miles per hour. If the DOT tape on that truck is not compliant, and does not meet photometric requirements, the car’s driver may not see the truck until he is 300 or fewer feet away. Since it takes a car traveling 70 miles per hour approximately 700 feet to stop, the outcome would be catastrophic.
Skipped Area of a Truck (no DOT tape in required areas) – one common error is to skip certain areas of a truck thinking that enough tape has been applied, or that that area is not important. To be clear, all areas required by law to be marked should be marked. Failure to do so leave that particular area vulnerable to accidents. The picture below shows a truck with no tape whatsoever on the Mansfield Bar or Under-ride bar. This is especially important since it is meant to reduce rear end collision fatalities and injury. To explain, this bar is meant to prevent cars from going underneath the truck in the event of a collision. Its low placement also provides an excellent location for reflective tape in that it is in line with car headlights. The tape placed higher up tends to disappear from view as cars get in close, but the tape on the lower bar would not. So having it completely missing from the truck creates an unnecessary hazard. See our article in the Science category above for more information on entrance and observation angles.
Another common issue with missing tape is not marking the sides of the truck with enough DOT C2 red and white tape. 50% is the minimum. (100% is optimal) Often when striping the sides of trucks, installers come across rivets or seams that make it applying the tape more time consuming, so they simply skip these areas. Or, in an effort to save money and time, they use less tape than what is required. Doing this creates blind spots for drivers at night that approach the vehicle. It also returns far less light to the drivers eyes than a fully marked truck. As the less conspicuous an object is at night, the higher the probability of an impact.
Going Above and Beyond Minimum Requirements
Most trucking companies choose to only meet the minimum requirements when it comes to reflective safety for their trucks. This is fine, just remember to keep your tape clean and in good condition so that it does not fall below standards and put others in danger. However, if you choose to go beyond the minimum requirements, there are some options.
First, DOT C2 simply means dot tape that is 2 inches wide. DOT C3 and C4 are also available and provide 50% or 100% more return of light. In some areas this width fits fine, and in other areas only a 2″ will fit. But wherever wider certified tape is used, visibility increases.
Also, certified tape can be placed in lower areas and even under the truck box. This provides a better entrance and observation angle for approaching cars. You don’t have to use a great deal of tape, but anything helps.
Reflective graphics are often used as both a safety measure, and advertising. This lights up a large portion of the side and/or the back of the truck trailer and/or cab. Definitely gets other drivers attention.
Outlining the Truck
One very effective measure that takes just a little more effort is to outline the silhouette of a large truck with reflective tape. This allows an oncoming driver to correctly identify the object he is seeing in the distance very quickly, often twice as fast. The tape used to out line the truck can be the same prismatic grade tape as the red / white DOT C2 tape used, or a less expensive type. It does not have to be the red white alternating pattern. And does not have to be a solid outline. Just a block of tape every few feet will work.
For more information on analyzing and preventing truck accidents, go to reflectivex.com
Steven Cole (Economics, MBA – University of West Florida , Business & Innovation – Stanford University) 25 years of experience in the reflective safety business. Specializing in vehicle accident and rear end collision reduction through increased visibility.