Driving experts recommend you glance at your mirrors every 5-8 seconds. That sounds like a lot but let’s look at what can happen in just 5 seconds:
- If you’re in motorway traffic travelling at 100km/h you will have travelled 138 metres in 5 seconds, and that’s a lot of ground covered where you could have been past on-ramps with other vehicles entering the motorway, or a vehicle could have pulled into the overtaking lane to overtake you.
- If you’re moving in motorway traffic that’s crawling, a motorcyclist could be filtering between the lanes or an ambulance could be trying to overtake you (something you can miss if you have your music on loud and can’t hear the sirens).
- In busy city traffic, cyclists could be filtering between lanes or riding along the left of slower moving traffic.
- If you’re driving below the speed limit (e.g. when towing a trailer) other vehicles can catch up with you quite quickly, and you should drive to allow them to pass when possible. Checking your mirrors while towing also lets you keep a check on the load you’re pulling. A vehicle travelling at 100km/h gains 30 metres every 5 seconds if you are driving at 80km/h. If you haven’t looked at your mirrors for a minute, a car could have come from a third of a kilometre behind you to be right on your rear bumper.
When we check our mirrors every 5 seconds we’re not taking a long look, it’s just a glance to check nothing has changed dramatically. If your gaze is lingering in your mirror, you’re spending too much time not looking ahead, and that could cause you to miss a developing hazard in front of you.
You will also be checking your mirror every time you want to change lanes, turn into or out of another road, brake, pull over onto the side of the road, or move off from the side of the road.
While we’re driving we have to take in a lot of visual stimuli and our short-term memory for what’s around us is not that effective. Glancing in the mirrors refreshes your memory of what’s around you constantly so that if something happens ahead and you need to take evasive action you’ve got a good idea of what’s on either side of you to give you more options.
Of course, to be effectively using your mirrors you must have set your mirrors up correctly with the rear view mirror showing the whole of your rear window and the wing mirrors not showing any of the sides of your vehicle unless you move your head.