Use low beam headlights  - Illustration copyright: whilerests

Proper Use of High Beam and Low Beam Headlights

Why is it important to know when to use high beams and when to use low beam headlights? Well, most of your driving tasks depend on vision and visibility. That is why driving at night and during inclement weather always poses a challenge and becomes more dangerous.

Your ability to see other vehicles, pedestrians, bicyclists, wild animals, or any other obstacles on the road is essential for safe driving.

A description of how to use of headlights properly is included in your driver handbook. It will also (most likely) be one of the items that pop up on your driver license or permit test. So, it is a good idea to study the below.

But learning the proper use of your headlights is also very important for your future and daily driving. In fact, improper use may have serious consequences.

Improper Use of Headlights

A study in Michigan (Insurance Institute for Highway Safety) showed that many drivers don’t turn on their high beams on dark roads, even when they should.

Other drivers may forget that they are driving with their high beams on and fail to the dim the lights when they overtake or meet another vehicle.

Both are equally dangerous. I will explain why.

How Much of the Road Can You See Ahead?

Your high beam headlights let you see about 350-400 feet a head. Low beam headlights illuminate the road for about 200 feet. You should always adjust your speed based on how far ahead you can see. If you your stopping distance becomes farther than you can see with your headlights, you are over-driving your headlights. If you overdrive your headlights, you will not be able to stop in time if there is an obstacle in your way.

When you travel 35 mph at night it takes roughly 200 feet to bring your car to a full stop on a dry pavement. If you travel faster on a dark road with your low beams on, you are basically driving blind and risk a serious crash. Even if you react quickly and hard braking slows your vehicle, hitting a pedestrian at 25 mph is likely to get the pedestrian killed or seriously injured.

If you want to drive faster on a rural road with no oncoming traffic, you must turn on your high beams (read more about when to use high beams here).

Why Can’t You Use High Beams All the Time?

It would, of course, be ideal if you could drive with your high beams on at all times, since they let you see farther ahead.

So, why can’t you? The reason you cannot do this is glare.

Glare is caused by bright light in your field of view. It can reduce your ability to see, create an intense feeling of discomfort, or both. When driving at night glare is often caused by viewing headlights from oncoming vehicles or headlights in your rear view mirrors.

When your eyes are exposed to glare, it becomes harder to see ahead. This means that your reaction time is increased when you are exposed to glare – but also some time after you were exposed. The glare has a lasting effect on your eyes since it takes time for your eyes to recover their ability to see normally.

Compare high beams - lowbeams. Adaption by driversprep. Original photo by andreiuc88

When You Must Dim Your Headlights

Keeping your headlights on high beam when you meet oncoming vehicles or approach another vehicle from behind cause glare and may blind other drivers.

This is why the law requires you to dim your high beam headlights at a certain distance from other drivers. The distance is usually set to 500 feet when you meet an oncoming vehicle and to 300 feet when you are approaching another vehicle from behind. The distance is based on how far high beams and low beam headlights reach and when they may become a problem for others.

High beam headlights are basically designed to be used in dark areas and when traveling at higher speeds. They are usually not needed when you drive in cities and towns.

It is a good idea to dim your headlights when you are driving in a city or other lighted areas with pedestrians, bicyclists, and other vehicles around. Just make sure you adjust your speed so you are able to stop within the distance you can see ahead.

Blinding Yourself with Your Own Headlights

High beams also create a problem when driving in bad weather, such as rain, snow, or fog.

When light strikes the water drops, only some of the light passes through while the rest scatters. Some also reflects back your eyes. This reflection of your own headlights reduces contrast of everything in your field of view and creates a glare, which will impair your vision.

If you turn on your low beams, it will reduce the scatter and the reflection, causing less glare. In most cases, this will also let you see the road better.

How to Use Low Beam Headlights Properly – a Summary

The light from beam headlights may cause glare. That is why you must use low beam headlights when you meet oncoming vehicles or approach another vehicle from behind. You should also use low beams in lighted areas, such as cities. To avoid blinding yourself you should also use low beams when driving in fog, heavy rain, or snow.

Remember to Slow Down

Remember, when you drive in bad weather and/or only your low beam headlights turned on, you must slow down. You must also increase the following distance since you cannot stop quickly.

Never overdrive your headlights and always keep a safe following distance.

Top illustration copyright: whilerests, second illustration adaption by driver’s Prep based on a photo by andreiuc88