Red light control for emergency vehicles
CROSBY – Misconceptions bear critically on the realities we face daily. Once while riding with a fellow worker we sat at a red light and were approached from behind by a fire truck. The truck struggled to pass the captive motorists at the light then announced that the emergency vehicle was going to proceed through the intersection with a loud honk.
“I don’t understand,” said my co-worker, “Why doesn’t he just use the button they all have to change the light?”
The answer is: the button did not exist. And, before we go any further – it is best to yield to emergency traffic; ambulances, fire trucks and law enforcement. If possible, pull over to the right to let them pass, don’t obstruct the emergency traffic, the life you save could be precious to you.
The button my co-worker was referring to did not at that time exist, but The Opticom™ system helps the emergency vehicles or first responders get through intersections that have signals by making temporary right-of-way using traffic controller functions.
A radio/global positioning system in the vehicle programs in position, speed and heading (direction) information from a satellite, the radio sends a priority request to a traffic control cabinet at the intersection.
“If the vehicle is approaching the intersection in a predefined approach corridor and requesting priority, the equipment provides an output to the traffic controller’s preemption input. The traffic controllers preemption input is programmed to provide a green light for the approaching vehicle,” according to the manual. Meaning it turns the lights green for the first responder.
All this activity is logged into a Computer Modem used for increased communication range as needed for the Harris County Traffic Method of Operation. The program will track a number of variables.
Where there are multiple first responders going to or from scenes or when there are simultaneous scenes whichever vehicle is in range first is granted the priority. The second will be serviced when the first clears the intersection. When a bunch of first responders are traveling at the same direction and approximately the same time all will be granted a green light that will hold six seconds.
Harris County vehicles now have both Opticom GPS radios and cellular modems, and also the intersections. Vehicle messages can now be sent via radio and cellular.
Opticom communicates with Harris County Traffic Controllers via ethernet while TXDOT intersections are connected via standard input. The Opticom equipment therefore provides a soft preemption to Harris County traffic controllers.