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Drivesmart column: Overdriving low beam headlights

The result is a speed about 40 kilometres per hour
Tim Schewe

By Tim Schewe

Have you ever given any thought to how far you can see at night as you are driving along down the highway? High beam headlights seem to overpower the dark, but there are a lot of situations where we are limited to using just the low beams. I was required to calculate the safe speed using only low beam headlights at a seminar and I was surprised at the result.

The Insurance Institute for Highway Safety (IIHS) says that most headlight systems do not perform well. For the 2022 model year about 40 per cent of the systems tested are rated marginal or poor because of inadequate visibility, excessive glare from low beams for oncoming drivers, or both.

Yes, the IIHS is an American organization but remember that Canada pretty much rubber stamps the American standards and calls them ours.

Most drivers can see a dark object at night with low beam headlamps at a distance of 25 metres. The sight distance may be greater with some of the better quality systems.

The average perception and reaction time for a driver who is paying attention is about a second and a half.

Using these facts, the result is a speed about 40 kilometres per hour. If you travel any faster or don’t pay full attention, you will collide with the object before stopping.

Dark objects such as pedestrians and deer are commonly found on the roads when we travel at night. Granted, there is other light to see by in town, but out of town, approaching and passing other vehicles, we are hurtling along at 80 and 90 km/h or more, and using only the low beams.

This seems to be a compelling reason to be a little more careful with our speed at night to me.

Now consider what could happen if one of your headlights was not working, or that both were so coated with dirt from winter driving that the full light output was not available. Complaints about vehicles with only one headlight are common and one only has to observe and count to see that this is true.

For your own safety it is well worth the time and money to keep your headlights clean and in proper working order.

Tim Schewe is a retired constable with many years of traffic law enforcement. To comment or learn more, please visit