I know the purpose of turn signals. When we turn, cars at the back know to slow down and vice versa. What about front turn signals?

How about front side marker lights? Rear ones make sense. You can see the distance between you and other cars in front of you. Not for front side marker lights. There are already headlights.

  • Gave an answer but this is about driving, not maintenance or repair.
    – Solar Mike
    Oct 7, 2020 at 5:27
  • You arrive at a 4-way stop, planning to make a left turn. You wait for the car opposite you to cross the intersection, but it doesn't go. You don't have the right of way, so you continue to wait. Nobody goes. What's the problem? Neither of you can tell that the other person is also turning left. Oct 7, 2020 at 14:03

4 Answers 4


So drivers travelling in the opposite direction know you have an intention to cross their lane.

You only need to check youtube to see drivers who don’t see cars in other lanes or those who don’t use the indicators (don’t know how to use, don’t know they are fitted...)


What Mike said and also:

  • On the highway; letting drivers in front of you know that you're switching lanes. That way they know that you're about to overtake them
  • When parked, oncoming drivers as well as drivers parked in front of you know you're about to drive off, so they know not to overtake or drive off.
  • When leaving a roundabout, oncoming drivers know they don't have to wait for you
  • When turning at a crossing, drivers that want to cross know they don't have to stop for you

Without a turn signal on coming drivers would not know if you are wanting to make a right/left hand turn. This would reduce safety if turn signals were not a thing. In other words its a form of communication with other users on the road.


Today I approached a give-way at a more major (but not very wide) road, and noticed a bus approaching. Because it was indicating to turn my way, I realised that I should stop short of the give-way line to allow it room to turn across the front of me. If I had stopped right at the line, we would have needed to reverse the priorities, which can be confusing for other road users.

Similarly you never know who might benefit from your turn signal (a pedestrian, a cyclist) which can advise them what is happening. The pedestrian might intend to cross the road where I am turning, etc. So the drill is to observe, signal your intentions, and make the manoeuvre. There may always be another road user that you didn't notice.

You also mention side indicator lights: you might be almost at the junction when someone looks at you, and can't see the front ones. Those lamps are also further out than the rear indicator lamps, so they are more visible in traffic from behind, and from the front when intending to pull out from a parking spot.

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