If you only look forward when driving, you’re unaware of more than 60% of what’s happening around you. Many driving instructors recommend checking in your mirrors every 5-8 seconds (although this varies) and, while that might sound like a lot, once you realise how far you can travel, and what can happen, in that time, it starts to make sense. All drivers have had an experience where they have gone to change lanes and realised another vehicle is there that they haven’t seen. This is the reason we need to keep looking around.
At 60mph you’re travelling at 26.8 metres per second. In 8 seconds you’ve travelled 214 metres. Cars travelling at 70mph are covering 31.3m/s or 250 metres per second, which means they’re gaining 36 metres on you every 8 seconds, and 270 metres every minute. If you’re not looking around you frequently at motorway speeds, a lot can change. You’ll also have passed vehicles entering the motorway on slip roads, and they could be moving to overtake you.
If you’re in traffic congestion on a motorway, motorbikes will be filtering through the lanes. If you arrive at a tailback and have to stop, you should be checking your mirrors to ensure that vehicles approaching you from behind have seen that you have stopped and aren’t going to plough into the back of you.
If you’re listening to music at higher speeds where the engine and road noise are more intrusive, you might miss emergency vehicles approaching from behind.
Knowing what’s around you helps you choose the safest time to change lanes to overtake other vehicles or leave the motorway.
In busy, slow traffic, cyclists could be filtering through traffic or approaching along the kerb.
If you’re driving in an area you’re unfamiliar with, you may need to make lane changes later than is ideal, and knowing what is around you helps you judge whether it’s safe to move.
When towing a trailer, you will often be moving more slowly than the general flow of traffic. It’s courteous to let other drivers pass when possible, so you’ll need to be aware of any build-up of traffic behind you. If you’re transporting a loose load, you can angle your mirrors so that you can see slightly more of your load if you want to keep an eye on it.
You will be checking your mirrors every time you slow down, change lanes, turn into or out of a junction, pull over at the kerb, pull away from the kerb, enter and leave a motorway, overtake and move back in after overtaking. Motorway slip roads are designed for merging so that you can see other traffic as you approach, but you still need to use your mirrors as you enter.
How should you check your mirrors?
First, your mirrors should be set up properly. When you check your mirrors you’re not going to take a long look, just a glance. The longer you spend looking in the mirror, the less time you’re spending looking ahead (although you will still have some peripheral vision ahead). The purpose is to get a quick appraisal of what’s around and to check there’s nothing that might cause danger.