I'll Share this Secret With You .....

[Bluerauder]

.... 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.

[justbob]

You are WAY too nice and well spoken Charlie. I want to get out of my van, walk around back, open the doors and grab a hammer, then proceed to the first car in line and show the driver the business end of it. Around here it is very common for the clueless to not pull far enough ahead to EVER trip the light.

Back when I had the motorcycles I would almost have to pass the line and signal the car behind me to creep up, I wasn't sure if it was weight related or magnetic field. Now I know :)

[CBT]

On the way to work it is pitch black every morning. If the light won't change and the only cars at the intersection are me and anyone behind me, I just proceed. I look and listen for emergency vehicles first, but that is never why the light won't change. I'm kind of high-strung, I have neither the time nor the inclination to sit at light for 5 minutes, plus I always feel like it's a set up for a car jacking or something.

[Pat]

The converse is true for me Charley. I pulled too far forward and the sensor detected, I presume, that my car had passed the intersection and since there was no other car behind me, being late at night, it never changed from red to green.

Sensing something like a ground embedded sensor, because I had seen work being done on this intersection, I backed up a good distance from the light and then came forward and stopped in the "zone" and voilà the light changed from red to green.

Good of you to post this tidbit, may save someone from going off the deep end.

Cheers,

[N40GL]

Those white cameras above the lights in Northern Virginia that point at the lanes? They do the same thing as the in-ground loop does: detect cars and trigger a light cycle.

[JBeezy]

I think most motorcycles have a lot of aluminum and that doesn't pick up. Just my $.02

[TAKEDOWN]

Yeah, those thoughts went through my mind too for the first 4 minutes. ;) As you found out, sometimes motorcycles have a hard time tripping the signal.

Makes me wonder how Toyota Corollas work. There ain't enough real metal in that car to simulate a tricycle at the sensor. :P


I'm well aware of this and I actually thought of purchasing a magnetic device that is placed underneath a motorcycle that assists in triggering the traffic light. I was stuck sitting at a light waiting for the green arrow to give me the gO ahead to make that left, but nada and this was 3am with no other cars to help out. Cleared and double checked may intersection and :burnout:

[Haggis]

I remember back in the early '80s in AZ. they had sensors under the traffic lights and when you flashed your highbeams it would change from red to green.

[CBT]

I remember back in the early '80s in AZ. they had sensors under the traffic lights and when you flashed your highbeams it would change from red to green.

So how many times did you flash your boobies trying to get the lights to change? :P

[Haggis]

So how many times did you flash your boobies trying to get the lights to change? :P

Wouldn't you like to know.

[CBT]

Wouldn't you like to know.

Well...I'd like to know at least once.

[Haggis]

Well...I'd like to know at least once.

I'll flash you a boobie the next time I see you.


Yea, Yea; That's what she said.

[Bigdogjim]

Problem in most area I travel through is car's are bumper to bumper and no wiggle room.

Some dufus is just sitting there waiting for who know what? Sometime I wish the big motorcoach had a push bar in the front:) :up:

Funny thing when I am driving the big motorcoach I have no real issues[with traffic] as I just look at in as downside to my job(driving for a living) now when I am in my car/truck watch out!!