# Trucker driving signals: left flasher **URL:** \ **Category:** Factual Questions\ **Created:** [January 8, 2004, 3:25am UTC](https://boards.straightdope.com/t/trucker-driving-signals-left-flasher/223355 "2004-01-08T03:25:02Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Kansas\_Man](https://avatars.discourse-cdn.com/v4/letter/k/eada6e/32.png) [@Kansas\_Man](https://boards.straightdope.com/u/Kansas_Man)\ **Post date:** [January 8, 2004, 3:25am UTC](https://boards.straightdope.com/t/trucker-driving-signals-left-flasher/223355/1 "2004-01-08T03:25:02Z")
I’ve noticed that many truck drivers will flash their left signal light after completing the pass of another vehicule. What is the exact meaning of this? Is it to thank the slower vehicule for allowing him to pass or to tell the guy in the left lane that he is now free to speed up and pass the two of them? Also, anyone know of a site where these driving customs are listed? I’d like to make a bumper sticker. ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [January 8, 2004, 3:29am UTC](https://boards.straightdope.com/t/trucker-driving-signals-left-flasher/223355/2 "2004-01-08T03:29:49Z")
I have never seen _anybody_ flash a left signal except to signal a left turn or lane change, but I have seen almost every trucker and a lot of four-wheelers flash their lights when someone lets them in when they’re changing lanes. If you are in the left lane, you might see only the left taillight and think the trucker is flashing their left signal. ---
**Author:** ![Hail\_Ants](https://avatars.discourse-cdn.com/v4/letter/h/dc4da7/32.png) [@Hail\_Ants](https://boards.straightdope.com/u/Hail_Ants)\ **Post date:** [January 8, 2004, 4:07am UTC](https://boards.straightdope.com/t/trucker-driving-signals-left-flasher/223355/3 "2004-01-08T04:07:00Z")
Usually what truckers do is this: [ul][li]The truck they’re passing flashes his headlights to let the passing truck know when he’s clear of him[/li]The passing truck will flash _his running lights_ (those 5 lights _| \*\*\* |_ along the top of the trailer) to thank him.[/ul] ---
**Author:** ![Kansas\_Man](https://avatars.discourse-cdn.com/v4/letter/k/eada6e/32.png) [@Kansas\_Man](https://boards.straightdope.com/u/Kansas_Man)\ **Post date:** [January 8, 2004, 4:12am UTC](https://boards.straightdope.com/t/trucker-driving-signals-left-flasher/223355/4 "2004-01-08T04:12:25Z")
I dunno. As I said, I’ve seen (Canadian) truckers flash their left signal after the move. It’s not the reflection from the other guy’s headlights… I guess I’ll to take a picture next time! ---
**Author:** ![Anachronism](https://avatars.discourse-cdn.com/v4/letter/a/e56c9b/32.png) [@Anachronism](https://boards.straightdope.com/u/Anachronism)\ **Post date:** [January 8, 2004, 4:17am UTC](https://boards.straightdope.com/t/trucker-driving-signals-left-flasher/223355/5 "2004-01-08T04:17:54Z")
Most truckers will turn their headlights on for a few seconds (or dim them at night) to let a passing truck know it is safe to come back into the lane. Truckers in their cars and others often do this for a passing truck also. It is hard to judge distance down the right side of the truck at a glance so this is helpfull. The proper thank you is to dim your parking lights momentarily (at night) or flash your four ways (hazard lights) for a few seconds. If you where to the left of a big truck the 4 ways would look like a left turn signal if that is all you could see although some truckers do use the left turn signal for ‘thanks’. Sometimes you get into the habit of flashing the 4 ways after you move back in the lane and do it even when the car did not give you the headlight flash. A lot of drivers use it as a general thank you too, you usually can’t see a ‘thank you wave’ in the cab of a big truck. ---
**Author:** ![TheLoadedDog](https://avatars.discourse-cdn.com/v4/letter/t/35a633/32.png) [@TheLoadedDog](https://boards.straightdope.com/u/TheLoadedDog)\ **Post date:** [January 8, 2004, 4:22am UTC](https://boards.straightdope.com/t/trucker-driving-signals-left-flasher/223355/6 "2004-01-08T04:22:46Z")
I’ve never seen that one. Some common ones I’ve seen though are: **Flash of right turn signal (bear in mind Aussies drive on the left):** “I know my truck is huge and you can’t see ahead, so I’m letting you know it’s now safe to cross to the wrong side of the road to pass me.” This practice is officially frowned upon. **Flash of brights from large truck being overtaken by another large truck - usually when they’re taking turns at slipstreaming:** “Your rear trailer has cleared my cab, and you can now merge back in front of me.” **Flash of hazard lights:** “Thanks!” ---
**Author:** ![bleach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bleach/32/3106_2.png) [@bleach](https://boards.straightdope.com/u/bleach)\ **Post date:** [January 8, 2004, 5:24am UTC](https://boards.straightdope.com/t/trucker-driving-signals-left-flasher/223355/7 "2004-01-08T05:24:14Z")
I’m pretty sure that a left turn signal flash means “Thank You” on the freeways of Los Angeles. I’ve seen tractor-trailers briefly blink their left turn signals in a “Thank You” context on several occasions. In each case, the scenario was the same that everyone has been describing as the “flash-the-lights-thank-you.” Most of the time, they use the flash-the-lights-thank-you though. ---
**Author:** ![dieselmech](https://avatars.discourse-cdn.com/v4/letter/d/aca169/32.png) [@dieselmech](https://boards.straightdope.com/u/dieselmech)\ **Post date:** [January 8, 2004, 5:45am UTC](https://boards.straightdope.com/t/trucker-driving-signals-left-flasher/223355/8 "2004-01-08T05:45:59Z")
Note don’t flash your high beams at night you don’t want to blind the driver of an 80,000lb truck. Instead turn your headlights off then back on. Most semi trucks in the US have a switch from the factory that allows them to blink the marker lights to thank the other driver. I have yet to see a car that has this feature. ---
**Author:** ![Dog80](https://avatars.discourse-cdn.com/v4/letter/d/6bbea6/32.png) [@Dog80](https://boards.straightdope.com/u/Dog80)\ **Post date:** [January 8, 2004, 8:39am UTC](https://boards.straightdope.com/t/trucker-driving-signals-left-flasher/223355/9 "2004-01-08T08:39:24Z")
> [@](#): > > \*Originally posted by TheLoadedDog \* > \*\*I’ve never seen that one. > > Some common ones I’ve seen though are: > **Flash of right turn signal (bear in mind Aussies drive on the left):** “I know my truck is huge and you can’t see ahead, so I’m letting you know it’s now safe to cross to the wrong side of the road to pass me.” Truckers do this in Greece all the time, because there are numerous mountain passes. Flashing the high beam usually means that there is a police radar ahead. ---
**Author:** ![TheLoadedDog](https://avatars.discourse-cdn.com/v4/letter/t/35a633/32.png) [@TheLoadedDog](https://boards.straightdope.com/u/TheLoadedDog)\ **Post date:** [January 8, 2004, 9:04am UTC](https://boards.straightdope.com/t/trucker-driving-signals-left-flasher/223355/10 "2004-01-08T09:04:37Z")
> [@](#): > > \*Originally posted by Dog80 \* > \*\*Flashing the high beam usually means that there is a police radar ahead. \*\* Yes, I forgot that one. Many dollars have remained safely in my pocket due to an oncoming driver giving a couple of quick bursts of high beam. Sure enough, there’s a radar trap down the road. I usually do it too. I might save another bloke a few bucks. I don’t do it if it’s a genuine accident blackspot, but usually it’s just a revenue raising excersise for the cops, so I don’t feel bad about it. I never warn anybody about a breathalyser unit though - drive drunk and take your chances.