Before making a lane change to your left, you must signal for at least three seconds. What else must you do? Before making a lane change to your left, you must signal for at least three seconds. What else must you do?

  • A. Check your blind spots

  • B. Slow down

  • C. Speed up

  • D. Use your brake lights to warn other drivers

  •  
    The correct answer is A
     
    You will have a blind spot over your left shoulder, so be sure to turn your head to check it
     
 
 
 

Blind spots when driving

We have blind spots in a vehicle because we have limited peripheral vision in our eyes, and our view is obstructed either by the vehicle's pillars or, if you are riding a motorbike, the helmet. Our field of view is almost 200 degrees, but on the edges we see very little detail. We can swivel each eye around 90 degrees and that gives us a horizontal field of view that can approach 200 degrees in some cases, without turning our head, but with not much detail on the edges.

Therefore when driving it's important that we turn our head and our eyes to look over our shoulder behind us.

When changing lanes it advisable to match your speed with the lane you are moving into as quickly as possible. If the left-hand lane is moving more slowly then you may need to slow down slightly in your lane first before moving over.

When you have made your manoeuvre, if you have slotted between two other vehicles then you will have effectively halved the following distance and therefore both you and the other vehicle might need to drop back to maintain the two-second rule. Watch out for traffic braking ahead as you move as this might leave the vehicle behind you nowhere to go if you brake sharply and have cut in too close to it.

This is especially important when you pull in front of a heavy vehicle which will take longer to stop.

Should you change lanes?

If it's not necessary to change lanes, don't do it. You may think you are jumping ahead of the traffic, but at a certain traffic density changing lanes actually slows traffic down as vehicles behind you will have to brake to accommodate your manoeuvre, thus slowing everyone else down behind them. If drivers ahead of you are doing the same that will affect your journey time. 

When you pull into the left lane, don't do it where another lane is merging. This video shows an example where the driver of the Audi is oblivious to what's going on around him and attempts to pull into a lane where another vehicle is merging at a motorway on-ramp.