Traffic light question

[stummej]

Ok so i now this really isn't a common question on a board like this but I know there are a few offices part of community. My question is what are the white lights the bar of traffic lights used for? I was stopped at an intersection today and all 4 sides came on and only one light was green for about a minute or two. Are they the emergency vehicle light changers?

[ipfd320]

out here in nassau county n.y....we use a white strobe lite mounted on the lite bar of the rig-- which the sensors on the traffic lite wires hang from...thats what changes the lite in the direction were going all others turn red

[w8jjr]

Yes they are.
Can be set off by strobe or IFR leds
In the old days flashing the spotlight on the rig across the sensor seveal times would set it off.

[BoxAlarm187]

They're part of the receiving system for the 3M Opticom traffic preemption system. In short, yes, it's part of the system that changes traffic lights for emergency vehicles. The white light is only a visual indicator that the reciever accpeted the signal from the emitter on the approaching EV, it doesn't serve any purpose than that.

[ve3nsv]

This link might help answer any questions you might have.

[stummej]

thanks for all the help!

[mikeydcg2003]

Tomar Also makes a Pre-emption system that looks quite similar to the 3M system. You can tell the difference most times as the receive heads on the Stop lights are a bit different looking and the strobes look a bit different on the trucks/vehicles. The systems can be locked down so that no other lights interfere with the system. The strobe lights have very short differnces in their strobe patterns which the light can distingush. These different codes can be put in the stop lights controller box so that only that cities units can change the lights. In the Des Moines area, premption is used in Clive, West Des Moines, Des Moines, Altoona, Plesant Hill, and Ankeny. Also these strobes can be hidden as such in Public Works vehicles. Most times the premptions strobes in the snow plows when running in teams of two or more are used and are mounted in the cab of the truck. They have a black cover over them so most traffic does not see it. How do i know this, My dad is one of the stop light managers for the City of Clive

[newsphotog]

I remember KCCI and WHO doing a story a number of years back about these pre-emption systems. Apparently in the earlier days these lights were readily available on eBay and it was causing some problems. Not sure if that is the case anymore since the systems have become more sophisticated like Mike has said.

[kc0jar]

Originally Posted by newsphotog

I remember KCCI and WHO doing a story a number of years back about these pre-emption systems. Apparently in the earlier days these lights were readily available on eBay and it was causing some problems. Not sure if that is the case anymore since the systems have become more sophisticated like Mike has said.

If I find someone with a preemption device in their vehicle, I'm taking them to jail. There's VERY few citations that I can't assign a dollar amount to, but Possession of Preemption Device is one of those citations that i can only cite someone into court, not write them a regular traffic citation for. Basically instead of paying a fine, they MUST appear in court.

[newsphotog]

Originally Posted by kc0jar

If I find someone with a preemption device in their vehicle, I'm taking them to jail. There's VERY few citations that I can't assign a dollar amount to, but Possession of Preemption Device is one of those citations that i can only cite someone into court, not write them a regular traffic citation for. Basically instead of paying a fine, they MUST appear in court.

No doubt. I can see some idiot who bought a pre-emption device off of eBay and then in their infinite wisdom they go flying down the street, thinking the light will change for them but instead it doesn't and they end up slamming into some innocent civilians because the moron didn't get a green light.

[mikeydcg2003]

Granted while premption does change the lights and make it safer for emergency vehicles, you have to consider they aren't going much faster than they would normally with lights on. It simply makes it easier to enter the intersetion and clear it as well so they make up time not having to slow almost to a stop and check the intersection.