# Floridians: What's that blue light on traffic signals? **URL:** \ **Category:** Factual Questions\ **Created:** [February 17, 2013, 8:26pm UTC](https://boards.straightdope.com/t/floridians-whats-that-blue-light-on-traffic-signals/650619 "2013-02-17T20:26:21Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![DavidPeab](https://avatars.discourse-cdn.com/v4/letter/d/54ee81/32.png) [@DavidPeab](https://boards.straightdope.com/u/DavidPeab)\ **Post date:** [February 18, 2013, 4:54pm UTC](https://boards.straightdope.com/t/floridians-whats-that-blue-light-on-traffic-signals/650619/21 "2013-02-18T16:54:16Z")
I’m not a Floridian, but I wonder if it has something to do with a sensor that detects a signal from oncoming emergency vehicles and changes the light from red to green so they can safely pass through the intersection. ---
**Author:** ![Hypno-Toad](https://avatars.discourse-cdn.com/v4/letter/h/b2d939/32.png) [@Hypno-Toad](https://boards.straightdope.com/u/Hypno-Toad)\ **Post date:** [February 18, 2013, 6:22pm UTC](https://boards.straightdope.com/t/floridians-whats-that-blue-light-on-traffic-signals/650619/22 "2013-02-18T18:22:22Z")
No. I’ve seen ambulances down here have to (carefully) negotiate red lights. Usually, not a problem unless all the lanes at the red light have cars in them. ---
**Author:** ![Gary\_Robson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gary_robson/32/3448_2.png) [@Gary\_Robson](https://boards.straightdope.com/u/Gary_Robson)\ **Post date:** [February 18, 2013, 7:55pm UTC](https://boards.straightdope.com/t/floridians-whats-that-blue-light-on-traffic-signals/650619/23 "2013-02-18T19:55:12Z")
> [@crucible](#): > > so, no one really knows what the blue lights are for. > > Quote > > What are the tiny blue lights on the backside of the stoplights?-Steve Clelland… [moderator note] **Crucible** , don’t cut and paste copyrighted text from other sites onto our board. If you wish to post a small excerpt, that’s fine, but only if you link to the original source. I have removed what you pasted and replaced it with a link to the original material. No warning issued. [/moderator note] ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [February 18, 2013, 8:52pm UTC](https://boards.straightdope.com/t/floridians-whats-that-blue-light-on-traffic-signals/650619/24 "2013-02-18T20:52:15Z")
> [@chappachula](#): > > You’re saying that there really is a good source of revenue here. So why doesn’t the city open a “camera operator” department? (just like they have a department of building inspectors, and health inspectors). > Are there technical problems make it unfeasible? It’s not just a matter of “operating” a camera, the way one might operate, say, a radar gun. It’s its own industry, covering manufacture, testing, procurement, installation, and monitoring of the cameras. It’s a bigger business endeavor than most cities want to get into, especially when they can lease the set-up and rake in their share of the dough with essentially no investment and no maintenance/operation headaches. ---
**Author:** ![AdamF](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/adamf/32/6246_2.png) [@AdamF](https://boards.straightdope.com/u/AdamF)\ **Post date:** [February 18, 2013, 11:44pm UTC](https://boards.straightdope.com/t/floridians-whats-that-blue-light-on-traffic-signals/650619/25 "2013-02-18T23:44:57Z")
I am not sure if this is relevant. In Calgary Canada, small blue light next to the regular traffic lights indicates that the automatic signal cycle has been over-ridden. Police, EMTs and buses can signal the traffic lights from about 1000 feet away, and they will get a green light when they arrive to the intersection. ---
**Author:** ![JRDelirious](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jrdelirious/32/9531_2.png) [@JRDelirious](https://boards.straightdope.com/u/JRDelirious)\ **Post date:** [February 18, 2013, 11:53pm UTC](https://boards.straightdope.com/t/floridians-whats-that-blue-light-on-traffic-signals/650619/26 "2013-02-18T23:53:27Z")
[aside] > [@Senegoid](#): > > Calif. is also the land of the [metered freeway on-ramps](http://www.mtc.ca.gov/news/congestion/ramp_meter_photos/I-580/8863D_049.JPG). Most of these also have a light facing the back side, so a cop can park ahead a ways, and see when the light is red. First time I ever drove in Cali (first time I ran into them, years ago) these got me scared good for the first few days. “Wait, does it have a light now? Does it always?” [/aside] ---
**Author:** ![Bullitt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bullitt/32/5725_2.png) [@Bullitt](https://boards.straightdope.com/u/Bullitt)\ **Post date:** [February 20, 2013, 1:17pm UTC](https://boards.straightdope.com/t/floridians-whats-that-blue-light-on-traffic-signals/650619/27 "2013-02-20T13:17:14Z")
> [@Dr.Strangelove](#): > > They’re here in Northern California as well. It seems they’re more common on the lights mounted lower on the side of the road (as compared to ones on the overhead pole). Where? I live on the peninsula and haven’t noticed them. I was up in The City on Sunday and didn’t notice any. Of course, I wasn’t looking or aware of this, and I’ll pay attention for them now. ---
**Author:** ![Spiff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spiff/32/9852_2.png) [@Spiff](https://boards.straightdope.com/u/Spiff)\ **Post date:** [February 20, 2013, 2:57pm UTC](https://boards.straightdope.com/t/floridians-whats-that-blue-light-on-traffic-signals/650619/28 "2013-02-20T14:57:13Z")
**Floridians: What’s that blue light on traffic signals?** They light up at 4 p.m. to signal that the blue plate specials are now being served at Perkins. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [February 20, 2013, 7:31pm UTC](https://boards.straightdope.com/t/floridians-whats-that-blue-light-on-traffic-signals/650619/29 "2013-02-20T19:31:00Z")
> [@echo7tango](#): > > Where? I live on the peninsula and haven’t noticed them. I was up in The City on Sunday and didn’t notice any. Of course, I wasn’t looking or aware of this, and I’ll pay attention for them now. There are at least a few in downtown San Jose, though I don’t remember precisely where. And I know for a fact that there is one on [this](https://maps.google.com/maps?q=sunnyvale&hl=en&ll=37.376374,-122.032152&spn=0.000791,0.000612&sll=37.346433,-121.89816&sspn=0.017843,0.019569&t=h&gl=us&hnear=Sunnyvale,+Santa+Clara,+California&z=21&layer=c&cbll=37.376374,-122.032152&panoid=XY5wxP9Yr6pCkKEVuJHepg&cbp=12,259.99,,1,-0.88) signal in Sunnyvale. ---
**Author:** ![kittenblue](https://avatars.discourse-cdn.com/v4/letter/k/ba8739/32.png) [@kittenblue](https://boards.straightdope.com/u/kittenblue)\ **Post date:** [February 21, 2013, 3:27am UTC](https://boards.straightdope.com/t/floridians-whats-that-blue-light-on-traffic-signals/650619/30 "2013-02-21T03:27:57Z")
Here in Ohio the blue lights are emergency-vehicle indicators that start flashing when an ambulance of fire truck approaches and the lights themselves lock on red. However…they don’t seem to start up until the emergency crews are practically underneath the lights, so they don’t really give enough warning time. ---
**Author:** ![Bullitt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bullitt/32/5725_2.png) [@Bullitt](https://boards.straightdope.com/u/Bullitt)\ **Post date:** [February 21, 2013, 3:33am UTC](https://boards.straightdope.com/t/floridians-whats-that-blue-light-on-traffic-signals/650619/31 "2013-02-21T03:33:45Z")
> [@Dr.Strangelove](#): > > There are at least a few in downtown San Jose, though I don’t remember precisely where. And I know for a fact that there is one on [this](https://maps.google.com/maps?q=sunnyvale&hl=en&ll=37.376374,-122.032152&spn=0.000791,0.000612&sll=37.346433,-121.89816&sspn=0.017843,0.019569&t=h&gl=us&hnear=Sunnyvale,+Santa+Clara,+California&z=21&layer=c&cbll=37.376374,-122.032152&panoid=XY5wxP9Yr6pCkKEVuJHepg&cbp=12,259.99,,1,-0.88) signal in Sunnyvale. I pass near that one in Sunnyvale. I’ll check it out. Thanks. ---
**Author:** ![Bambi\_Hassenpfeffer](https://avatars.discourse-cdn.com/v4/letter/b/bbe5ce/32.png) [@Bambi\_Hassenpfeffer](https://boards.straightdope.com/u/Bambi_Hassenpfeffer)\ **Post date:** [February 21, 2013, 4:38am UTC](https://boards.straightdope.com/t/floridians-whats-that-blue-light-on-traffic-signals/650619/32 "2013-02-21T04:38:19Z")
> [@chappachula](#): > > So are these blue lights intended _only_ for the police? Or are they useful to all drivers? The way the newspapers explained it when they were first rolling out years ago is that the police at an intersection CANNOT write a citation for running a red light if they cannot _directly_ tell that the light is red. Every major intersection around here (Pinellas County, FL) has them (except ours are white), and they illuminate when the light they’re attached to is red. [This](http://blogs.orlandosentinel.com/community_lakemary_blog/2008/08/a-question-an-a.html) is from the Orlando Sentinel explaining them in more detail. > [@crucible](#): > > so, no one really knows what the blue lights are for. The first two responses in this thread said basically the same thing I just did. But I’ll call this out here so you see it directly this time. ---
**Author:** ![Bullitt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bullitt/32/5725_2.png) [@Bullitt](https://boards.straightdope.com/u/Bullitt)\ **Post date:** [March 3, 2013, 9:12pm UTC](https://boards.straightdope.com/t/floridians-whats-that-blue-light-on-traffic-signals/650619/33 "2013-03-03T21:12:03Z")
> [@Dr.Strangelove](#): > > There are at least a few in downtown San Jose, though I don’t remember precisely where. And I know for a fact that there is one on [this](https://maps.google.com/maps?q=sunnyvale&hl=en&ll=37.376374,-122.032152&spn=0.000791,0.000612&sll=37.346433,-121.89816&sspn=0.017843,0.019569&t=h&gl=us&hnear=Sunnyvale,+Santa+Clara,+California&z=21&layer=c&cbll=37.376374,-122.032152&panoid=XY5wxP9Yr6pCkKEVuJHepg&cbp=12,259.99,,1,-0.88) signal in Sunnyvale. > [@echo7tango](#): > > I pass near that one in Sunnyvale. I’ll check it out. Thanks. I just drove by that intersection in Sunnyvale and I didn’t see any blue light there. There’s a lot of construction there, so things might be changing, but the lights looked like they haven’t been touched by the construction and are still pretty new. This is an area with new and ongoing construction. ---
**Author:** ![furryman](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/furryman/32/99_2.png) [@furryman](https://boards.straightdope.com/u/furryman)\ **Post date:** [March 4, 2013, 3:07pm UTC](https://boards.straightdope.com/t/floridians-whats-that-blue-light-on-traffic-signals/650619/34 "2013-03-04T15:07:02Z")
The blue light goes on when there’s a sale at K-Mart. ---
**Author:** ![Bullitt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bullitt/32/5725_2.png) [@Bullitt](https://boards.straightdope.com/u/Bullitt)\ **Post date:** [March 4, 2013, 3:11pm UTC](https://boards.straightdope.com/t/floridians-whats-that-blue-light-on-traffic-signals/650619/35 "2013-03-04T15:11:12Z")
There’s no K-Mart there, but there’s a (relatively) new Target. Maybe they removed the blue light altogether. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [June 21, 2013, 4:41am UTC](https://boards.straightdope.com/t/floridians-whats-that-blue-light-on-traffic-signals/650619/36 "2013-06-21T04:41:46Z")
> [@echo7tango](#): > > I just drove by that intersection in Sunnyvale and I didn’t see any blue light there. There’s a lot of construction there, so things might be changing, but the lights looked like they haven’t been touched by the construction and are still pretty new. This is an area with new and ongoing construction. I finally had a chance to walk by the light again and snap a picture. See [here](https://www.dropbox.com/s/il3k4wjgfn3o14s/2013-06-20%2020.37.23.jpg) (the blue light is about 1/3 from the left and 1/2 way down). There’s another similar light above it (also on the backside of the signal) that glows red–I think when the cross street has a green light. Didn’t spend enough time observing it to really figure out the pattern, though. ---
**Author:** ![Bullitt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bullitt/32/5725_2.png) [@Bullitt](https://boards.straightdope.com/u/Bullitt)\ **Post date:** [June 21, 2013, 5:00am UTC](https://boards.straightdope.com/t/floridians-whats-that-blue-light-on-traffic-signals/650619/37 "2013-06-21T05:00:57Z")
Cool, Dr. S, I’ll go check it out. Thanks. ---
**Author:** ![SpyOne](https://avatars.discourse-cdn.com/v4/letter/s/82dd89/32.png) [@SpyOne](https://boards.straightdope.com/u/SpyOne)\ **Post date:** [June 21, 2013, 8:35am UTC](https://boards.straightdope.com/t/floridians-whats-that-blue-light-on-traffic-signals/650619/38 "2013-06-21T08:35:33Z")
> [@pkbites](#): > > Which is fine, but maybe people wouldn’t run lights so much in Florida if they didn’t stay red so gawddam long! I timed one in Sarasota at 4 minutes 30 seconds!:eek: WTF? In Connecticut the law said that if a light had been red for 2 minutes, you could assume it was broken and proceed accordingly. ---
**Author:** ![SpyOne](https://avatars.discourse-cdn.com/v4/letter/s/82dd89/32.png) [@SpyOne](https://boards.straightdope.com/u/SpyOne)\ **Post date:** [June 21, 2013, 8:45am UTC](https://boards.straightdope.com/t/floridians-whats-that-blue-light-on-traffic-signals/650619/39 "2013-06-21T08:45:02Z")
> [@chappachula](#): > > So are these blue lights intended _only_ for the police? Or are they useful to all drivers? > And–a related question: > If they are intended only to help the cops—why not use cameras, instead of little blue lights? Imagine you are in a police car racing as fast as you can to the site of a shooting. You are approaching an intersection (with your lights and siren on), and the light is red in your direction. You need to slow down and proceed carefully, because traffic on the other streets may not have heard your siren yet. Is their light green? Is it red yet, and your is preparing to turn green? The answer to those questions could make a big difference, just as the few seconds you might save could make a big difference. Years ago, the community I lived in started a bus service, and the buses had a cool feature: right next to the central brake light were two other lights, one green one yellow. It rapidly became obvious what the lights meant: green meant the driver was pressing the gas pedal, yellow meant neither gas nor brake. I often wonder why I haven’t seen that on more vehicles since. ---
**Author:** ![SpyOne](https://avatars.discourse-cdn.com/v4/letter/s/82dd89/32.png) [@SpyOne](https://boards.straightdope.com/u/SpyOne)\ **Post date:** [June 21, 2013, 8:47am UTC](https://boards.straightdope.com/t/floridians-whats-that-blue-light-on-traffic-signals/650619/40 "2013-06-21T08:47:25Z")
> [@crucible](#): > > I have seen screwed up lights in Florida, esp. where the size of the road is large, multi-lanes, and they split out the left turn lane or lanes such that they are not right next to the lanes continuing straight ahead…then they give the left turn lanes a green light instead of a green arrow. The green light does not mean you have the right of way, but a driver might not understand that and could pull directly into oncoming traffic. hard to explain until you are there and confused whether you should go, or not. Locally, they just replaced solid green for left turn lanes with a blinking yellow arrow, which is IMO clearer about what it means. [Previous page](https://boards.straightdope.com/t/floridians-whats-that-blue-light-on-traffic-signals/650619.md?page=1)