At night, it's very dangerous for you to drive with one headlight. Do you know why? It's primarily not because you can't see as well, although that does make it slightly more hazardous, especially if you drive too fast. At any speed much over 100 km/hr, you are driving 'beyond your headlights'. This means that, even if you have an excellent reaction time and good brakes, you will not be able to stop in time to avoid hitting anything that appears in your headlights; your vehicle is moving too fast to come to a stop in the distance illuminated by them. That's one reason more deer are hit at night; if you drive too fast, when you see the deer it's too late to stop. Having only one headlight doesn't decrease this distance, but it does illuminate less of the road, making it less likely you'll see that deer. No, the real reason why having only one headlight can be deadly for you is a little more insidious. It has a lot to do with the way your brain perceives things it can't make out clearly. For example, suppose you're driving at night, and you see this light on the road in the distance: >>> Being a good driver with lots of experience, your brain has become conditioned to 'understand' what this is ... it's a vehicle approaching you. The vehicle is far off in the distance, because the two headlights appear as a single light source. Your eyes aren't good enough to distinguish two lights, so your brain assumes they're there, and you unconciously think 'this car is still far away'. Not a problem, as long as it's what you expect. As the car gets closer, your eyes will confirm what your brain 'expected'; the lights will spread apart, revealing a car getting closer and closer. Now lets look at a different situation. Here's a similar light in the distance: >>> Your brain assumes it's a car far in the distance. But it's not! It's actually a car with one headlight, and it's much closer than your brain assumes. The danger lies in the fact that your brain interprets the single headlight as a pair of headlights much farther away. As a result, you will assume that you have plenty of time ... for example, to make a left turn, should you need to. In reality, the oncoming car is much closer than it 'appears', and if you were to stop and turn, you could very easily be hit. So why is driving with one headlight dangerous for you? Well, every driver that comes toward you will be misjudging the distance between your vehicle and his, every time! Only one of these oncoming vehicles needs to misjudge the distance while making a left turn, and both of you will become a statistic! So get that headlight fixed, O.K.? Resources HTML, graphics & design by Bill Willis 2023