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Traffic Signal Pre-emption Systems

A few weeks ago, there was a tragic story in the news about an EMT who was killed when the ambulance in which she was riding – on a call – was broadsided at an intersection. The story was all the sadder because the EMT was so young – she was just 22 – and was working her last shift before heading off to graduate school.

As of this writing, all the details aren’t in, but however it turns out, when emergency vehicles – fire trucks, police cars, ambulances – are on the move, the circumstances are often dangerous.

Many traffic signals are equipped with sensors that enable them to detect the flashing strobe lights on emergency vehicles. (By the way, in case you’re thinking of trying to game the system by playing around with your high beams, the sensors respond to lights that are flashing at a very high rate, and some traffic lights work only when there’s a specific pattern to the flashing. Overall, traffic signal pre-emption systems are pretty sophisticated, and, in any case, it would be illegal for unauthorized people to have one.)

Anyway, there’s now a new, smarter system that also keys off turn signals, and changes the lights ahead based on the turn direction, rather than just what’s directly in the path of the emergency vehicle. The system is tied into the turn signal so it now knows if the emergency vehicle is making a turn at a light, and, if so, which way it’s going. It then aligns the lights along the cross streets in the direction the vehicle’s heading in to clear the path. This gives any “civilian” cars and trucks that are there a chance to clear out, because they’ll have a green light. And when the emergency vehicle gets there, it will have a clear shot.

GTT’s Opticom is one system that handles the turn signals. There’s a pretty good, high level video of how their system, which combines GPS and Infrared technology, works here. (You may want to skip the intro about why it’s important, and get to the “how it works” stuff, which starts about three minutes in.)

If it makes things safer for emergency vehicles (and those along their way), and gets those emergency vehicles to those in need faster, I’m all for it.