# What Does the Flashing Yellow Light on Top of Trucks, etc. Mean? **URL:** \ **Category:** Factual Questions\ **Created:** [December 24, 2003, 3:55am UTC](https://boards.straightdope.com/t/what-does-the-flashing-yellow-light-on-top-of-trucks-etc-mean/220781 "2003-12-24T03:55:08Z")\ **Posts on this page:** 5\ **Page:** 2
**Author:** ![fire](https://avatars.discourse-cdn.com/v4/letter/f/67e7ee/32.png) [@fire](https://boards.straightdope.com/u/fire)\ **Post date:** [December 24, 2003, 8:24pm UTC](https://boards.straightdope.com/t/what-does-the-flashing-yellow-light-on-top-of-trucks-etc-mean/220781/21 "2003-12-24T20:24:38Z")
Colored lights and their meanings vary form State to State. In Missouri, Blue lights are for volunteer firefighters. Red lights are emergency vehicles (police, fire&ems)…SOME tow trucks can run red lights, but I don’t know how that works. Green lights are used by Fire Dept’s to signify the command post. Yellow lights are on large or slow moving equipment Purple lights are on funeral procession vehicles. The old Missouri laws stated that red=police; blue=fire; green=ambulance. But as time went on, ‘experts’ found that red was more visible during certain conditions, blue was more visible during other certain conditions…blah blah blah. Because of those reports, emergency vehicles started running red/blue combinations to cover all the conditions and the law was ignored for the most part. You may also notice yellow rotating lights on the rear end of fire trucks now. They started showing up in the early nineties because the National Fire Protection Agency said they should be on there. As stated before, yellow lights are more for attention, so you don’t run into them when they are moving slow or making weird turns while plowing a parking lot. The purple lights are a more recent addition to the Missouri laws for funerals. As I said before, each state is different and in some states, each county can be different. If you are a volunteer firefighter with blue lights on your vehicle and you travel to a state that use them on police cars, be prepared to get pulled over. They will make you either take it down or cover it up. ---
**Author:** ![Mr.Slant](https://avatars.discourse-cdn.com/v4/letter/m/c57346/32.png) [@Mr.Slant](https://boards.straightdope.com/u/Mr.Slant)\ **Post date:** [December 24, 2003, 9:41pm UTC](https://boards.straightdope.com/t/what-does-the-flashing-yellow-light-on-top-of-trucks-etc-mean/220781/22 "2003-12-24T21:41:36Z")
Cookingwithgas wrote: Once I called the police because I saw a tow truck blatantly running a red light to get to an accident. They confirmed that he had no legal right to do so but probably wouldn’t do anything unless a police officer had seen it. — End Quote — I seem to recall hearing that in _some_ states tow truck operators have bona fide emergency vehicle status, but _only_ when responding to requests to help clear a roadway. The story I read involved a guy trying to cut a tow truck that was responding to an accident with lights on off by means of opening said guy’s driver’s side door. Supposedly the private vehicle driver got cited for failure to yield to an emergency vehicle. I suppose it kinda’ makes sense. If someone can prevents hundreds of persons from being inconvenienced for hours, their presence is something of an emergency, and depending on visibility conditions and availability of flares and other warning lights, a tow truck arriving in a timely fashion could actually save lives. ---
**Author:** ![bughunter](https://avatars.discourse-cdn.com/v4/letter/b/aeb1de/32.png) [@bughunter](https://boards.straightdope.com/u/bughunter)\ **Post date:** [December 24, 2003, 10:41pm UTC](https://boards.straightdope.com/t/what-does-the-flashing-yellow-light-on-top-of-trucks-etc-mean/220781/23 "2003-12-24T22:41:53Z")
Wait, I thought: - Red Lights: How about a date, big boy? - Blue Lights: Always Low Low Prices - Yellow Lights: umm… Diaper needs changing? - Red and Green Lights: Happy Holidays! - Black Lights: Bachelor Ahead or (in late October) Oooh, Scary! Never mind. Carry on. ---
**Author:** ![St.Urho](https://avatars.discourse-cdn.com/v4/letter/s/8e7dd6/32.png) [@St.Urho](https://boards.straightdope.com/u/St.Urho)\ **Post date:** [December 25, 2003, 3:13am UTC](https://boards.straightdope.com/t/what-does-the-flashing-yellow-light-on-top-of-trucks-etc-mean/220781/24 "2003-12-25T03:13:38Z")
Here’s a link to the [Minnesota](http://www.revisor.leg.state.mn.us:8181/SEARCH/BASIS/mnstat/public/www/DDW?W%3DTEXT+PH+IS+%27authorized+emergency+vehicle%27+ORDER+BY+SORT_KEY/Ascend%26M%3D11%26K%3D169.64%26R%3DY%26U%3D1) Statutes regarding red, blue, and amber lights. And here is the statute regarding [white lights](http://www.revisor.leg.state.mn.us:8181/SEARCH/BASIS/mnstat/public/www/DDW?W%3DTEXT+PH+IS+%27authorized+emergency+vehicle%27+ORDER+BY+SORT_KEY/Ascend%26M%3D10%26K%3D169.55%26R%3DY%26U%3D1) In my area, green is used to signify the command post, but it is not used en route, and to the best of my knowledge is not regulated by law. St. Urho EMT/Firefighter ---
**Author:** ![St.Urho](https://avatars.discourse-cdn.com/v4/letter/s/8e7dd6/32.png) [@St.Urho](https://boards.straightdope.com/u/St.Urho)\ **Post date:** [December 25, 2003, 3:16am UTC](https://boards.straightdope.com/t/what-does-the-flashing-yellow-light-on-top-of-trucks-etc-mean/220781/25 "2003-12-25T03:16:44Z")
White lights should be white strobes. [Previous page](https://boards.straightdope.com/t/what-does-the-flashing-yellow-light-on-top-of-trucks-etc-mean/220781.md?page=1)