Swich for traffic lights

**highlander** · 07-12-2012, 05:41 PM

Does anyone here know if emergency vehicles {fire truck,ambulances,police cruisers} have a transmitter that can change the sequence of traffic lights? Coming home from Salem the lights at the Walmart stopped working. There were several fire trucks ambulances and the like in the parkinglot. Lights going down Hghland ave to Lynn and traffic going to Salem lights were stuck on red while the traffic out of the WM parking lot was non stop. Traffic was stopped for the better part of 10 min and backing up badly. Cruiser came thru the intersection and lights went back to normal,don't think it was a coinsedence.

**ntomsw** · 07-12-2012, 05:44 PM

They do, although I have no link to prove that. Everytime I am at an intersection though, I notice a blinking yellow strobe light on top of the poles go off, and all the lights turn red. After the emergency vehicles go through, they go back to green.

**davemata** · 07-12-2012, 05:46 PM

yeah they do, more important question: How do we work it?

**Maxpower** · 07-12-2012, 05:47 PM

Sure they do. Google MIRT. Not for civilians though.

**Zappa** · 07-12-2012, 05:50 PM

Many emergency vehicles have coded strobe lights, that flash at a particular pulse rate, which are read by sensors mounted on the traffic light pole. It causes the traffic signal lights to turn green in the direction of travel for the emergency vehicle, and red for all the cross streets.
Some of the poles also have a small white strobe light on top that will flash when the signals lights are in emergency mode. This is an indicator for the emergency vehicle drivers so they know that all the cross street traffic lights are now showing red.

**CdP** · 07-12-2012, 05:52 PM

Friend of mine at MIT in the late 90s took a class where they would build one, test it on the crosswalk on Mass Ave right in front of the student center, but then "had" to dismantle it. Allegedly. Sounded pretty simple. Unfortunately, pretty simple engineering is still above my head!! :)

I heard if you took a class, submitted two sets of fingerprints, had an intense background check, an interview with your Chief of Police, and then paid your fee, you could talk about it on the internet.

**quincy** · 07-12-2012, 05:53 PM

There are plans somewhere on the internet that show how to build a transmitter but if you're caught using it, well........you will be in world of hurt.

**RKG** · 07-12-2012, 06:30 PM

Yes. It is called a "Pre-Emptor," and works off the strobes.

You can tell when a light set has been captured by the Pre-Emptor: a white beacon will show in all directions at the captured light.

If the rigs are properly wired, the Pre-Emptor is disabled if (a) vehicle transmission is set in "Park" (hydraulic brakes) or (b) Maxi brake valve is opened (air brakes). Purpose of the interrupt is to prevent extended (and unnecessary) intersection capture if the rigs go off at an incident at the intersection. However, the interrupt is not always properly installed.

See http://www.ehow.com/info_7750006_pre...c-signals.html

**Coyote33** · 07-12-2012, 07:03 PM

I also thought you were looking to buy one. That would be pretty handy to have for saving time and gas.

There IS this, though: TV-B-Gone® universal remote control

**n1oty** · 07-12-2012, 07:07 PM

Some cities and towns have these and some do not.

Swich for traffic lights

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