Stephen F. Austin State University
February 13, 2002
Driving at Night and How it CanBe Safer
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Car accidents are among the leading causes of death in America,and have become increasingly problematic in other countries as well.The National Highway Traffic Safety Administration (NHTSA) revealedthat more than half of the fatalities involved with car wrecks eachyear occur at night (Electronics Now, 1999). Some of these can beattributed to difficulty with visual perception in the dim lightassociated with night. In the dark, drivers must rely solely onartificial light sources, and many individuals have a hard timemaking out shapes such as animals and tire shreds on the side of theroad at night. This can become hazardous if an animal is actually onthe road, or even if it is something like a tire.
Another problem some nighttime drivers encounter is that of unseenroad signs or cautioning information. Some signs may be too hidden toreflect enough light to the driver, or they may just not bereflective enough. Maybe, as the driver passes, they do not have timeto read the sign. Like many drivers who have driven unfamiliar backroads or country roads, a person often will learn that it is verydifficult to navigate the turns while going fifty miles an hour whenyou have not been there before. Road lines may be too faint or notreflective enough, or there may not be anything that lets you know toslow down for a curve ahead. Also, country roads sometimes have odd,unexpected stop signs that can easily be missed, or seen too late.All of these reasons, plus many more, are the cause of nighttimeautomobile wrecks. There has been quite a bit of research done ondrivers' safety, and some done on drivers' safety at night. This hasled to some advances in traffic safety for nighttime drivers, and hascreated even more questions to be researched to further the knowledgeof night vision in relation to driving abilities.
The previous research done on nighttime visual perception hashelped many aspects of road and highway development. Although onlyone-fourth of driving occurs at night, it still represents animportant part of driving as a whole (Electronics Now, 1999). Factorsto make night driving safer must be included when designing roadsigns, traffic lights, caution information, and automobiles. Some ofthe past findings have resulted in reflective lines on the road andsigns, as well as different types of headlights. Retroreflectivematerials, or materials that return reflected rays back towards thesource of illumination, have been studied for use on road lines,signs, and safety clothing for pedestrians and cyclists. The FederalHighway Administration (FHWA) has a Photometric and VisibilityLaboratory in McLean, Virginia where they are able to test possiblesolutions to visual problems associated with driving. Here, theseretroreflective materials are tested to help to ensure that they areseen during dark conditions (Arens & Reilly, 1998). The increasein visibility in dark conditions is due to the extra light photonsbeing reflected onto the retina, allowing not only more colorinformation, but better detail information. The positive results thematerials have received are seen in their large usage in safetyclothing and gear as well as on bikes and road signs. Anotherprecaution that has been taken is to ensure that the materials do notfade and lose the qualities that make them retroreflective. The Labhas therefore tested how long these materials last in the sun andelements before they must be replaced (Arens & Reilly, 1998).
Headlights are another area of study to make night driving safer.The Photometric and Visibility Laboratory has reviewed a few types oflights for possible implementation. Metal-halide lamps, which haverecently been introduced in luxury cars and other high-endautomobiles, have been found to produce a bluish tint, while the moretraditional tungsten-halide lights produce a more reddish color. Thebluish tints that come from the metal-halide headlights make colorsappear more like they would in daylight (Arens & Reilly, 1998).This is helpful with road signs and other driving information thatpeople universally associate with color, as well as seeing moreaccurately what is in the range of vision. Ultraviolet (UV)headlights have shown to be useful when paired with fluorescentmaterials. Signs made of fluorescent material can easily be seenduring the day when the sun provides UV rays, and they can alsoincrease the distance at which they can be detected at night whenpaired with the UV lamps. The UV lamps are used in addition tostandard low-beam headlights. The problem that is found withfluorescent materials is that they do not maintain their propertieswhen exposed to environmental elements. Right now, the materialsbeing researched for this application only last for six months to oneyear without replacement. Replacing the materials so frequently wouldnot be a cost-effective method. Currently, new fluorescent materialswith longer predicted lives are being tested. A useful lifespan wouldbe five or more years. The UV lamps are still being looked into, andthey may be used to create a beam pattern, or light range, much likethat of the high beams now in use (Arens & Reilly, 1998). Onceperfected, the fluorescent and UV combination may be a great successin keeping signs and lines more visible.
One of the newest answers to nighttime vision problems is theCadillac's new Night Vision technology. This new system is designedto allow the driver to see objects in the dark, by using infrared(IR) wavelength rays, or thermal imaging (TI). Night Vision has beenfound to allow the driver to see three to five times farther than thetraditional low beams, by viewing a monochromatic virtual imagedisplay at the bottom part of the windshield. In the periphery of thedriver the images are displayed above the dashboard, so as not tointerfere with the driver's vision. One of the most important aspectsthat the creators included is that the virtual objects appear thesame size as they would while looking out of the window, so not onlydo the drivers not have refocus their eyes, but they are better ableto judge distances. The field of view for the device is four degreesvertically, and eleven degrees horizontally, and the hotter objectsin the range appear as white. The technology allows a driver not onlyto see animals and pedestrians at longer distances, but also to seepast the glare of an oncoming vehicle (Electronics Now, 1999; Smiley,2000/2001). Generally such glare renders some people temporarilyblind, but with Night Vision they can now see objects through theglare by simply looking down a bit. There are some criticisms that,because people continuously adapt to new situations, they will adaptto this system and feel overly confident about driving inlow-visibility conditions (Akerstedt & Kecklund, 2001). Long-termtesting of this product will provide more useful information aboutsuch technology as the infrared screen.
In another area of research, Peter Hall (1999) suggests that apossible concern with reading the road signs at night is due to theirlettering. This is because most road signs are printed in all capitalletters, while most of what people read everyday is mixed case.Meeker and Associates discovered that the typeface in use now is moredifficult to read, while a new font called Clearview is much morevisible at night, as well as easier to read quickly. This new fontwould include upper and lower-case, because people are used to themin every day life, which would benefit from top-down processing(Hall, 1999). This would help distinguish between words as well as beuseful for word recognition. The ability to more clearly understandthe immediate surroundings and read road signs should lead to a saferdriving atmosphere.
In order to make drivers more aware of the driving conditionsahead, a few European countries have worked on testing "blinkinglights", which are miles upon miles of light-emitting diode flashersset upon posts along side the road. The diodes can be manipulated tochange blinking patterns, change colors, or even change intensitiesof light. They are expected to warn drivers of any conditions ahead,such as traffic buildup, construction, or wrecks. The theory behindthis is that earlier warning provides longer available reaction timefor drivers (Moran, 1999). The flashing diodes would add a changingstimulus to the repetitiveness of the road when necessary, whichwould better attract the attention of the driver. The lights wouldremain constant and therefore would not be a distraction, unlesssomething important lies ahead. The key to this is to avoid overuse.As found by Enns, Austen, Di Lollo, Rauschenberger, and Yantis(2001), a change in contrast captures attention much as a newstimulus, so that would be a good aspect to research. Only a fewcolors and patterns of the diodes would be used, so as to minimizeconfusion and distraction. The results from the European studies sofar show that the general speed declines as the patience of thedrivers increases (Moran, 1999). More research should be done priorto bringing this "blinking light" technology to the UnitedStates.
There have been a great number of ideas researched as well asactual advances made in safety for night driving, but there are manymore to come. Research has just begun on new materials such aspaints, signs, and other reflective materials important fordetection. A continuation of the current research on fluorescentmaterials coupled with the UV headlights could possibly providedrivers with a great aid in seeing at night. As for the researchersfor Cadillac, further research and study can determine if NightVision technology will provide an important tool for driving in thefuture. "Blinking light" results from the European trials will allowfor greater knowledge as to what to implement in America for earlierwarnings. There are multiple areas of research going to helpnighttime drivers, but nothing can improve safety if the drivers arenot cautious and educated about the higher difficulty of visualperception at night.
Akerstedt, T. and Kecklund, G. (2001). Age, gender, and earlymorning highway accidents. Journal of Sleep Research, 10,105-120.
Arens, J. and Reilly, M. (1998). FHWA's photometric and visibilitylab (Federal Highway Administration). Public Roads, 61, (4),16-20.
Enns, J., Austen, E., Di Lollo, V., Rauschenberger, R., andYantis, S. (2001). New objects dominate luminance transients insetting attentional priority. Journal of Experimental Psychology:Human Perception and Performance, 27, 1287-1303.
Hall, P. (1999) Signs of the times (new typefaces for road signs).I.D., 46, 124.
Moran, T. (1999). Blinking lights offer freeway clue to drivers.Automotive News, 74, 321.
Night vision for your car. (1999, June). Electronics Now, p31-32.
Smiley, A. (2000/2001). Auto safety and human adaptation. Issuesin Science and Technology, 17 (2), 70-77.