Bluerauder
06-14-2011, 04:38 PM
.... or maybe its not so much of a secret to experienced drivers. However, I think that only a miniscule number of people in Northern Virginia know this.
In our areas, many traffic signals are controlled by sensor loops in the ground. Basically, they are wire loops embedded in the asphalt that can sense a vehicle through Magnetic induction.
Today enroute to work, I got trapped on an exit ramp with a signal at the top of the hill. Two lanes turn left and one lane goes right. I was about 6 cars back in the rightmost left turn lane.
Because of heavy traffic on the cross road, the light went Green and no one could move. The light changed back to Red and no one had moved an inch.
I immediately suspected that there would be a problem. It was. This signal normally cycles on a 2 minute schedule. After more than 4 minutes, I jumped into the right lane and made a right turn on Red (after a full stop of course). As I suspected, I saw the light change in my rearview mirror as I was headed away from my destination to make a U-turn.
The Secret: If you haven't already guessed was that when the light went back to Red and no one had moved, the detector wasn't able to detect any cars. It relies on the movement of the metal mass to see it. My car passing by the line was enough metal mass to trigger the sensor to change the light. I suspect that the rest of those cars would have sat at that light all day without a little help.
So, if you are ever caught at a traffic signal that seems to be taking forever to change, just roll forward a couple inches to a foot. The sensor will "see" you and change.
I have found this little "trick" secret to be very useful .... especially off-peak and late night. But it does help at all times. My advice .... if the light seems a tad long -- move a little bit.
In our areas, many traffic signals are controlled by sensor loops in the ground. Basically, they are wire loops embedded in the asphalt that can sense a vehicle through Magnetic induction.
Today enroute to work, I got trapped on an exit ramp with a signal at the top of the hill. Two lanes turn left and one lane goes right. I was about 6 cars back in the rightmost left turn lane.
Because of heavy traffic on the cross road, the light went Green and no one could move. The light changed back to Red and no one had moved an inch.
I immediately suspected that there would be a problem. It was. This signal normally cycles on a 2 minute schedule. After more than 4 minutes, I jumped into the right lane and made a right turn on Red (after a full stop of course). As I suspected, I saw the light change in my rearview mirror as I was headed away from my destination to make a U-turn.
The Secret: If you haven't already guessed was that when the light went back to Red and no one had moved, the detector wasn't able to detect any cars. It relies on the movement of the metal mass to see it. My car passing by the line was enough metal mass to trigger the sensor to change the light. I suspect that the rest of those cars would have sat at that light all day without a little help.
So, if you are ever caught at a traffic signal that seems to be taking forever to change, just roll forward a couple inches to a foot. The sensor will "see" you and change.
I have found this little "trick" secret to be very useful .... especially off-peak and late night. But it does help at all times. My advice .... if the light seems a tad long -- move a little bit.