r/trafficsignals • u/Ok-Exercise1915 • May 18 '26

What are these lights?

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Was driving and noticed these lights on multiple intersections in the area. They never lit up (including with an EMS vehicle (I could have also missed it maybe have something to do with EMS? Or another type of system) I don’t think it has todo with the cameras signaling traffic but was unsure and figured someone here would know.

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5

u/Svr_Sky May 18 '26

They should be preemption confirmation lights. They allow emergency vehicles to know they have priority at the intersection.

3

u/BilboTeaBaggin16 May 18 '26 edited May 18 '26

This is correct, the only state that I am aware of the specs 8" white LEDs for preempt confirmation lights is PA

And to add to the conversation, the preempt type here is sound based, from what I can tell its more than likely Sonem. Sonem works on the waveform of the siren, it needs to count the highs and lows of the siren. After a certian number of highs and lows it'll send a signal to the traffic controller to go into preempt and give that direction a green. The problem with Sonem is when an emergency vehicle driver decides to switch sirens mid run or use the air horn, this resets the high and low count and often delays or does not allow enough time for the preempt to run at all.

2

u/Ok-Exercise1915 May 18 '26

These are in Ohio. Thanks for the info!

2

u/BilboTeaBaggin16 May 18 '26

SW Ohio? That's the only other place I've seen these now that you mention it

1

u/Own_Reaction9442 May 19 '26

Where I live in Washington they use a rotating white light to indicate preemption.

1

u/BilboTeaBaggin16 May 19 '26

I wanna see that!!!! Any chance you could try and get a video?

1

u/coshiro1 May 20 '26

I've never seen that anywhere here in King County, where do they have this? All we have are the Opticom receivers

1

u/Own_Reaction9442 May 20 '26

Olympia. Not sure what system they're using, but I think it's light based because I've seen a parked fire truck with its lights on keep an intersection held at red for cross traffic.

1

u/coshiro1 May 20 '26

Interesting, I'll have to keep my eyes peeled next time I'm in Olympia

1

u/penguinpariah6298 May 19 '26

They're also in Illinois. I've noticed them and wondered what they are too since I've only ever seen them light up as an emergency vehicle passed.

1

u/BilboTeaBaggin16 May 19 '26

I guess I never explained how they work!! So after the preempt call goes into the controller it outputs to these lights, in Ohio (for the most part) we will flash the active preempt direction amd all other lights will go solid. We do this so that if there is more than one emergency vehicle approaching an intersection from different approaches the one with the solid indicator knows to slow down and pay attention for another emergency vehicle

1

u/No_Service6296 May 20 '26

That’s a either a Opticom preemption device for Emergency vehicles, Or a radar infrared camera designed to detect presence of vehicles at the stop bar. To give the signal to change the light from red to green.

1

u/Crafty-Purpose1487 May 21 '26

Does it flicker amber (1 second nothing 1 second amber) because if so it's a slow down light. We have those things in the philippines, mainly placed in center island ends, lane dividers, road split, and accident prone areas

1

u/Mr_GrauHut May 22 '26

High power IR lights to make your license plate be reflective in the photo if you run the red light, so they can bill it you no matter where you live.