The Importance of Headlight Aim

Headlamp AimAfter 20 years of full time traffic policing you accumulate many memories. I was reminded of one on the weekend when a small pickup passed me by and I could see the bright patch from the right low beam headlight shining on the pavement about 3 meters in front of the vehicle. The memory concerns a driver who thought headlight aim was unimportant.

I had stopped that driver in much the same circumstances and issued a repair order for his vehicle. He did bring the order back to the detachment showing that the repair had been carried out, but it was inside a card offering to buy me coffee so I could sit down, relax and hopefully not take the issue so seriously.

Why Worry About Headlight Aim?

According to lighting expert Daniel Stern, "Lamp aim is by far the main thing that determines how well you can (or can't) see at night—it's even more important than the output and beam pattern of the headlamps themselves."

If you don't worry about it, your vehicle may never have it's headlights properly aimed. Canada's Motor Vehicle Safety Act does not require vehicle manufacturers to aim them before delivery to a customer. If you are purchasing a new vehicle, ask the dealer if the pre-delivery inspection includes checking that headlight aim is accurate.


If your headlight beams are set too low your ability to see at a distance is reduced. Set them too high and you can see further down the road but illumination of the pavement for vehicle guidance is affected.

Mis-aligned headlights can prevent oncoming drivers from seeing properly, possibly with severe consequences.

Oddly enough, a driver with mis-aligned headlights is more susceptible to glare from oncoming vehicles. The difference between light levels of oncoming lamps and the visual task area while driving at night is smaller when your headlights are properly aimed than when they are not. Your eyes see the latter situation as one with more glare.

Professional Aiming

If you are going to have a repair or body shop adjust your headlights, make sure that they will be using an optical beam aiming instrument. Here's an example of instructions for using a headlight aiming instrument from Hella.

Do It Yourself Aiming

Doing it yourself is possible, but definitely not the best choice. There are detailed headlight aiming instructions on how to do the job on Daniel Stern's site. Be prepared to spend a significant amount of time to accomplish this.

Accuracy in adjustment is critical. If your headlights are misaimed by just half a degree, the amount of usable light projected even 23 metres (75 feet) ahead could be compromised and potentially useless.

Sorry sir, I still think that headlight aim is something to be taken seriously!

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Thanks for this week's material, Tim.  I can only imagine how many memories you accumulated over twenty years of service.  Reading about them is always a nice touch, and I especially like the image of you receiving a card and a suggestion to relax. 

Someone I know recently bought a late model used vehicle, and just yesterday, he remarked to me about how wonderfully effective his new wheels' headlights are.  Lights are so easy to take for granted, but I've been trying to pay more attention to mine in the past few years.  In addition to doing simple stuff, like keeping them clean, I've been keeping tabs on their alignment, too.   It's good to know I'm fighting the war against oncoming glare!