Driving when visibility is reduced, be it from weather conditions or low light, brings two main challenges to the driver; the ability to see where you are going and the ability to be seen by other road users. Car headlights have two settings: high beam and low beam. What do these two settings do, and when should you use each setting?
High beams are brighter and project a symmetrical beam to illuminate the road ahead for a longer distance. The low beam uses an asymmetrical beam to illuminate a shorter distance of the road ahead. Low beam is for city driving where there are streetlights; high beams are for dark roads.
Motor vehicle headlights have come a long way from the days of an oil lamp in a lantern with a reflector, but the advancements come with a need to understand how the modern headlight works. There are many different types of headlights, but the main headlights will always have the same minimum functions. Low beam and high beam are required features to make the vehicle roadworthy. Let’s take a look at these two features, how they work and when to use them.
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What’s The Difference Between High And Low Beam?
High beam and low beam are sometimes known by different terminologies, depending on where you come from. High beams are sometimes referred to as main beam, full beam, brights, or driving beam. Low beam is sometimes known as passing beam, dipped beam, dims, or meeting beam.
Many people believe that the difference between the high and low beam setting on motor vehicle headlights is simply a difference in brightness. There is somewhat more to the difference between the two settings than this.
The main differences between high beam and low beam include the following.
Brightness
The high beam is significantly brighter than the low beam.
Distance
A high beam illuminates the road for a longer distance than high beams, allowing you to see further ahead. Low beams illuminate a shorter distance of the road ahead.
Field of view
The low beam illuminates a wider angle than the high beam, which lights up more of the peripheral aspects of the road than the distance ahead. High beams are a narrower beam that gives better distance, but less peripheral illumination.
Symmetrical illumination
High beams provide a symmetrical illumination of the road ahead, meaning that both sides of the road, as well as the distance ahead, are illuminated. Low beams illuminate the road asymmetrically, meaning the side of the road for oncoming traffic is illuminated less, but the road in your lane is illuminated as well as the edge of the road on your side.
These are the main variances between the two types of headlight beam, but you still need to be aware of when it is appropriate to use each beam type on the road. Some circumstances and road conditions will influence your choice of which beam to use. Road safety is a key aspect in your choice of beam, not only for your own driving safety but also for the safety of other road users.
When To Use Low Beam
Low beam is a low intensity, dipped, asymmetrical setting on the headlights of a car. Knowing when to use this setting is paramount for your own visibility of the road and the safety of other road users.
Low beams should be used for city driving where the road is well lit by streetlights. Low beams should also be used when coming up behind a car ahead of you and when an oncoming vehicle is noticed. Bad visibility conditions such as fog, rain, smoke, dust, or snow require the use of low beam.
City streets
City streets that are lit by streetlights provide good overall lighting of the road and the verge, which means that low beam is appropriate for these conditions. The low beam is more to make you visible to other road users. Even on dimly lit city streets, there is usually enough ambient light on the streets to make low beam sufficient for safe driving. Darker roads may require the occasion high beam for better visibility, but it should not be kept on permanently, but only as needed.
Coming up behind another vehicle
Many new drivers forget about this circumstance, but high beams approaching a vehicle from behind will reflect in the rearview mirror of the car ahead and dazzle or blind the driver of the vehicle in front of you. If your lights are on high beam and you come up behind another vehicle, you should always switch to low beam.
Oncoming traffic
When traffic is approaching you in the opposite lane, high beam will be shining directly in their eyes, making it difficult for them to see clearly. You should switch your lights to low beam when oncoming traffic approaches you, which will dim your lights and direct the beam away from the oncoming driver.
Low visibility conditions
Low beams are the best setting to use when there is low visibility on the road caused by rain, fog, smoke, dust, or snow. The low beam will illuminate the road at a lower level without reflecting the beam back at you and is thus the better headlight setting in these conditions.
When To Use High Beam
High beam is the high intensity, bright, symmetrical setting on the headlights of a car. Knowing when to use this setting is important to give you a sufficient view of the road ahead without causing visibility and safety issues for other road users.
High beams should be used for rural or country road driving or stretches of highways that are not well lit. They can also be used with discretion in city driving where the road is dark, and lighting is minimal. The use of high beams should always be done with the consideration of other road users in mind.
The high beam setting on your headlights is intended for use on dark roads where there are no streetlights and very little ambient lighting from surrounding structures and dwellings. High beam gives you a good distance view of dark roads or highways.
High beam gives you a clearer view of the road ahead, including obstacles in the road, the condition of the road surface, and other potential dangers. Because the high beam shines far ahead, it gives you enough time to take the appropriate action for any dangers that are encountered.
When Not To Use High Beam
There are certain circumstances on the road where the use of high beam is not appropriate, even if the road is dark and not well illuminated.
High beams should not be used when coming up behind traffic in front of you or when oncoming vehicles in the opposite lane are approaching you. High beams are also not suitable where visibility on the road is reduced due to fog, rain, snow, dust, or smoke.
If you are coming up from behind on slower traffic in front of you, you must switch your headlights to low beam. High beam will reflect in the rearview mirror of the driver ahead and can dazzle them, causing them to lose visibility and potentially result in an accident.
When traveling on a dark road and oncoming traffic approaches you, you must switch your headlights to low beam to avoid temporarily blinding the oncoming driver with your high beams.
Bad road visibility conditions that result in particles in the air are not good circumstances for the use of high beams. These conditions include rain, mist or fog, snow, dust, and smoke.
One may think that the high beam would be able to penetrate the particles in the air better than low beam and give better visibility through the particles, but this is not the case.
The particles in the air scatter the bright beam, and some of the particles will reflect the light directly back toward you. This has the effect of dazzling you and reducing your visibility. Low beam that illuminates at a lower level reflects less of the light back towards you and gives you better visibility in these conditions.
How To Use High Beams
The use of the high beam setting must be used responsibly and with the safety of other road users in mind. There are some basic driving dos and don’ts for using high beams.
When approaching the crest of a rise or a hill, you can usually see the glow of the headlights of oncoming traffic. If your headlights are on high beam, you should switch them to low beam so that when you or the oncoming vehicle crests the hill, you do not dazzle the other driver.
Likewise, when approaching a sharp bend in the road, you can see the glow of the headlights of approaching oncoming traffic. Set your headlights to dim before rounding the curve to avoid temporarily blinding the approaching driver.
Always change your headlights from high beam to low beam when approaching vehicles in your traffic lane from behind. This way, you will not blind the driver ahead of you with your high beams reflecting in their rearview mirror.
Low Beam Vs. High Beam Symbol
There are standard symbols on every vehicle that indicate which mode your headlights are currently in and indicators on the controls for high beam and low beam.
The high beam indicator on your dashboard will illuminate when high beams are on. This symbol is an image of a headlight with a series of horizontal lines emanating from the front of the light. This symbol on the dash will be illuminated with a blue light when the high beams are on.
The indicator for high beams on the light controls will be the same symbol. The indicator for low beam is the same headlight icon, but the lines emanating from the front of the headlight are angled downwards, indicating a low beam.
How Low Beam Works
Low beam works by dimming the intensity of the beam and dipping the beam to a lower angle. The beam is also changed to be asymmetrical so that while it still illuminates your driving lane, the light does not shine brightly into the lane for oncoming traffic.
The low beam effectively positions the beam forward, down, and at an angle away from the oncoming traffic lane. In the countries where motorists drive on the left of the road, the low beam will be angled towards the left. In countries where people drive on the righthand side of the road, the low beam will be angled towards the right.
The regulations that control the amount of light on low beam that spills over into the oncoming lane is less strict in North America, which is governed by the SAE standard. International standards governed by the ECE regulations are much more strict on the amount of light entering the opposing traffic lane.
How High Beam Works
When you click on the high beam setting for your headlights, the beam is lifted to project further into the darkness, the intensity of the light is increased, and the beam includes illuminating for of the entire road, including the oncoming traffic lane.
In the early days, the high beam and low beam were activated by a manual footswitch on the floor of the car. The controls have advanced to be electronic and have moved to be hand-controlled rather than foot controlled. The high/low beam control is often on the same control on the steering column that switches the lights off and on.
Many vehicles have a temporary high beam on the same control, which will momentarily switch the high beams on when you pull the control towards you, and the high beams will go off when the lever is released.
Are There Different Bulbs for High Beams And Low Beams?
The mechanism used in your car for high beam and low beam will depend on the age of your car and the technology the manufacturer of your car has adopted as a standard.
Some vehicles use a two-bulb system with a halogen bulb for low beam and an HID bulb for high beam. The halogen and HID bulbs cannot be swapped around due to different connection types. Some designs have a single bulb with two filaments, one for low beam and the other for high beam.
LED headlights are being used by some auto manufacturers, and these lights are gaining popularity because of their low energy consumption for equivalent brightness of other bulb types.
Laws For Using High Beams
There are actually traffic laws around the use of high beams that many drivers are not aware of. Traffic laws state that if you are driving with your high beam on, you must switch to low beam when you are within 500-feet of an oncoming vehicle.
There are also traffic laws governing approaching a vehicle from behind with your high beam engaged. The regulation states that you must switch from high beam to low beam when you are within 200 to 300-feet of the vehicle in front of you.
Conclusion
In summary, low beam headlights are most commonly used for city driving and where visibility on the road is obscured due to smoke, rain, fog, dust, or snow. Low beams direct the beam of the headlights down and away from the oncoming lane of traffic so as to not affect the eyesight of drivers approaching in that lane.
Low beam is also the appropriate setting to use in areas that require headlights to be on during daylight driving. This helps to make you more visible on the road, even in the daylight.
High beams are intended for use on dark roads, such as in the country or highways that do not have streetlight illumination. High beams can adversely affect the eyesight and the driving ability, and safety of other road users. Consequently, you must turn off your high beam when within 500-feet of oncoming traffic and within 200 to 300-feet of traffic ahead of you in your driving lane.
Learning the effects of high and low beam and the appropriate time and place to use each setting is an important part of becoming a safe, considerate road user.