Test Your Reaction Time


   Reaction time is the time it takes for you to react to a stimulus. At night, you spot a deer on the road ahead of you on the highway ... how long will it take you to react and start to move your foot toward the brake pedal?



   If you're travelling at 120 km/h, this means you're moving forward about 33 metres every second. So if your reaction time is about one second, which is very typical for an average driver, you will have traveled about 33 metres towards the deer before you even start to brake! So if a deer appears within 33 metres of the front of your vehicle, you will hit it!

   Now assuming you slam on the brakes, the distance you will travel before coming to a stop, under ideal conditions and including the 33 metres before you even touch the brakes, is somewhere around 100 metres.

   Your headlights on high beams ideally will reach out somewhere between 90 and 150 metres. Given that you may be tired, possibly looking away while talking to a passenger, or sipping a coffee, all of which will increase your reaction time, and that your brakes may not be brand new, it is highly likely that if you see a deer suddenly at the far range of your headlights, you will be unable to stop in time to avoid hitting it!
This is especially true if your speed is higher than 120 km/h.


   This is called driving beyond the range of your headlights. What you see you will hit. This can be incredibly dangerous if there is a possibility that a moose might be on the road. You will die if you hit a moose. Deer can usually be hit without killing you, as long as you don't try to swerve out of the way and hit a tree or roll your vehicle into the ditch. Moose, not so much.

   My late wife Jane once had an encounter with a moose; she wasn't going very fast, and managed to come to a stop right at the moose, who was facing away from her, unmoving. She must have actually nudged his legs, because he sat down on the hood, leaving a big dent.

   I once had a scary encounter with one as I was driving down the highway late at night. The moose appeared suddenly beside me in the window as he came carreening to a stop as I went past. I glanced at his terrified face as he bounded backwards and back toward the ditch. I must have whacked his knees, though, as I later discovered that the rear fender had a big crack in it.

   The obvious remedy if you're driving at night and don't want to hit an animal is to decrease your speed, regardless of the posted speed limit. The posted limit is for daylight and dry roads.



   Below is a simple test you can try that will give you an idea of your best possible reaction time. This does NOT correspond to the situation above where you are moving a foot, and have to do it unexpectedly. Here you will be ready. But it will give you an absolute lower limit to your reaction time.

Click on 'Start', and wait until the colour of the box changes. As soon as it changes, hit 'stop'




You can see how far forward your vehicle, if moving at 120 km/h, will travel, by multiplying your best time above by 33. For example, if your reaction time was 0.425 seconds, your vehicle will have moved forward by 0.425 x 33 or 14 metres.

What hasn't been discussed here is the effect of alcohol on your reaction time. With each drink consumed: one shot, one beer, one glass of wine ... your reaction time doubles!


See also our page on why you should never drive at night with one headlight


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