Our aspiring off-road driver, Bud, has always marvelled at the way some people mounted the dazzling arrays of auxiliary driving lights on their 4WD vehicles, and although it seemed to him that some of these vehicles were meant for nothing else but night driving judging by the sheer number of auxiliary lights some was carrying, he had the feeling that some installations bordered on the ridiculous. However, the only off-road driving experience Bud had were the few hours of basic instruction at his off-road club training area, and he knew next to nothing about auxiliary driving lights.
Nonetheless, Bud was nothing if not eager to learn; therefore, he was particularly pleased when the first of the lectures he was attending at an official training day at the club was about auxiliary driving lights and night driving in general. However, Bud was two minutes late and only caught the Instructor’s second or third sentence, which started thus:
“Nobody likes driving at night because of the fact that we can only see around 5% of what we can see in daylight, and while this is not much of a problem in the urban setting because we have more artificial light and therefore more visual information in the form of street lights, shop signs, road markings, the lights of other vehicles, and even traffic lights available to us, off-road driving at night is something else altogether.”
“In the off-road situation in Africa, whether South Africa or the larger Southern African region, you only have the lights fitted to your 4×4, and sometimes moonlight, which may or may not be enough to let you see where you are going. But then again, you should never be in the bush by yourself, and especially not when you are driving at night. It is not safe because anything can happen: you can fall into a ditch you did not see, or run into a large animal like for instance, a hippo if you are near water, a herd of sleeping elephants, or a pride of lions. Admittedly, lions do not usually attack 4WD vehicles at night, but it has been known to happen, and especially by lone males out patrolling their ranges.”
“However, being attacked by wild animals is not your biggest problem; your single biggest problem is that you just cannot see where you are going. If we ignore just for the moment the fact that you should not be out driving at night in the bush, and especially not by yourself except in a dire emergency, you should remember that the human eye is not adapted for night vision; you cannot see colour for instance, which could be important to determine the types of obstacle you may suddenly come across. A case in point would be the fact that a wet saltpan, like the ones you get in the Kgalagadi, or the Kalahari Dessert, as it is also known, would be virtually indistinguishable from a bare patch of smooth wet sand if you saw both at night in only the headlights of your 4×4. Smooth sand may not be much of a problem, but a wet saltpan could have you sunk up to your floor plates in two seconds flat.”
“Apart from losing your ability to see colour, your depth perception is also severely degraded. This means that you cannot perceive relative distances at night as well as you can during daylight. “What this means in practice is that you might seriously misjudge the distance you need to stop in an emergency, however, that is not all; at night you also lose much of your peripheral vision, which means you lose much of the vision from the corners of your eyes. In practical terms, all of this means that if you were barreling down a two-wheel track at night at 50 km/h, you would not be able to see the colour of the ground, accurately judge the distance to the elephant or hippo on the track, or see what might be lurking between the trees as you pass them, such as animals that could jump into the road in front of you, as for instance, kudus are fond of doing.”
“Driving at night might not leave you blind, but the cumulative effect of degraded depth perception, loss of colour and peripheral vision, as well as the several types and degrees of night blindness you might suffer from without knowing it might make it too dangerous to drive at night; especially if you are alone and do not have the benefit of being able to follow the lights of a second vehicle.”
Auxiliary driving lights
“Of course, there are ways to get around much of the effects of reduced vision at night. You could for instance not drive at night, or you could fit one or more types of auxiliary driving lights. However, the most common mistake many off-road drivers make is the fact that they fit auxiliary lights that look good, instead of fitting lights that work well.”
• Fog lights:
“Fog, or mist, is a common problem in Southern Africa, but driving in mist requires a special type of light. Mist is composed of fine water droplets that reflect much of the light emitted by ordinary white driving lights back at the light source. This is why using spotlights makes the mist seem denser than it really is, and especially in low ambient light conditions. What you need is a light that does not cause as much glare, and fog lights do this by not spreading the light beam throughout the mist cloud, and not, as you may have been led to believe, because the lenses are yellow.”
“Not all fog lights are yellow: in fact, lens colours range from clear to yellow to amber, all the way to red. Nor are all coloured lights fog lights: what makes a particular light more suitable for fog driving than any other has more to do with the shape, or pattern of the light beam than anything else does. You may have the best fog lights in the world but if you mounted them at the height of the headlights, you may have as much glare as using white spotlights, so this is where the pattern of the light beam comes in.”
“Normal headlights have a cone-like pattern that spreads out to nearly the same height as its width, with the result that the light beam is driven right into the fog. Fog lights on the other hand, are flat on top, meaning the reflector does not allow the light beam to propagate upwards. This means that when the fog lights are mounted as close to the ground as is practicable, the beam sort of “pushes” in under the fog. The result is that the road is lit up under the mist, where it is the least dense, thus, because the beam does not penetrate the fog upwards, glare is reduced, making the light beam effective in both mist and dusty conditions.”
• Spot lights:
“Whatever kind of light you use for normal head lighting, always bear in mind that the object of effective lighting is to enable you to see as far ahead down the road as you can. Good spotlights should always have a tightly focused beam that lights up the road straight ahead for as far as you can get them to light up the road. You can always fit a second set of lights that are angled towards the sides of the road, but the problem with this is that it might distract or blind oncoming drivers, but that should not be an issue in the bush.”
“However, you will not always be in the bush; you might be driving on public roads at night, so make sure all your auxiliary driving lights conform to the law in respect of how they are controlled, as well as their mounting positions. Headlights are generally subject to laws that regulate their height above the ground as well as how far apart they can be. The same thing goes for auxiliary lights; how you fit them might light up the area around your 4×4 for miles around, but they could also blind oncoming drivers for miles around. Therefore, whatever lights you fit, first make sure they conform to the law in all the countries of Southern Africa, because as you go off-road driving in Africa, you will find that what is legal in one country is illegal in another, so make sure your lighting conforms to the law in all the countries you plan to visit, or travel through.”
Night Driving: Auxiliary Driving Lights or Not?
“Nonetheless, standard lighting is often sufficient for most conditions in South Africa as well as most of Southern Arica. Standard headlights are designed to provide the best possible combination of light spread, luminosity, and reach, all of which are functions of their placement and construction. Modern headlights are several orders of magnitude better than what was available even just ten years ago, so the question should not be so much do we need auxiliary lights, but do we want to run the risk of developing electrical issues and problems because of them? Properly installed driving lights should not cause issues, but are they really worth the hassle, since you should not be doing any off-road driving after dark anyway?”
“Notwithstanding anything you may have seen in off-road magazines and in shopping mall parking lots, many of the ridiculously overdone auxiliary lighting installations are illegal, because they blind oncoming drivers, and since you will not be doing much off-road road driving at night because it is dangerous, you may have to be content with one set of auxiliary driving lights for both dust and mist conditions during daylight, and then not to see all the way to the other side of the dust or mist cloud, but to make yourself more visible to other road users, irrespective of where in Africa you might find yourselves.”
