Laser "falses" in tool booths w/EZPass?

[JNewell]

The new NH EZPass lanes with the light thing overhead set off the laser detector on my X50. The lanes that do not have the overhead lighting (if that's what it is?) do not. That's just about all I know about this...I just hit the mute button when my wife's in the vehicle. If someone has more info, I'd be interested to read about what's up.

[guardian]

Only had laser alerts happen in one specific booth, everytime I went through it, just South of the Albany entrance. I'll try mounting my V1 pointing straight up next time see I go through the regular ones @ the Whitestone Bridge...speaking of which..

I always get 2-3 X band signals at the Whitestone Bridge booths..and I got a warning letter once for doing like 17 instead of 5 or something stupid..

I always thought they somehow timed your passage through the booth using the signal from the EZ Pass itself, but if people are getting laser everytime... that's very interesting..

[Ethel]

There is a major toll booth setup where the Dulles Toll Rd ends and Rt. 66 (or some lead-in road to Rt. 66) begins, here around Tyson's Corner in Vienna, Virginia. The system we use is Smart Tag, similar to EZ Pass.

I haven't been running radar around this area for a while so I'll have to check what's happening these days, but I recall that often times the V1 would go off indicating Ka band. At first I thought it was the machines, but more than once I've seen an unmarked bolt out of nowhere and go after someone who just blew the toll at 75+ mpg.

Jamal, have you noticed this?

[kpatz]

I went through the Everett Turnpike booths last weekend with my new X50, and quickly discovered how piercing the Laser sound is on it. :shock: :?

With the V1, which I had visor mounted, I didn't get an alert until I was exiting the booth. Also, sometimes the rear arrow would light right after the front arrow. The X50, which was mounted at the center of the windshield, alerted when I was in the middle of the booth throwing my tokens in (yes, I'm still using up my stash of tokens). This reaffirms my belief that the source is overhead. The X50 is sounding sooner due to its position on the windshield, so it gets a better "view" overhead. The V1 can see forward but not directly "up", so it's probably seeing a reflection of the signal and alerting because it's so sensitive to laser.

I'm going to get a hardwire kit and visor clip for the X50, so once I get those I'll have to see how much difference it makes in the X50's picking up this mystery toll booth laser signal.

I think, since the beam is coming from overhead, that it's there either to sense the presence of a vehicle, or to determine its size, presence of a trailer, etc. I doubt it could measure speed using traditional Lidar techniques at that angle. I suppose it could measure speed if there's 2 beams and it senses the amount of time between the car hitting the first beam and the second though.

[kpatz]

Just some updates on this ongoing mystery. In re-reading this thread, I saw this:

Some EZ-pass booths have a laser monitoring system. I don't know what they use it for, but it's definitely there. If you get a laser alert at a particular booth, look up. You will probably see a box on a pylon with a glass window. I've only seen this at one booth and it's also the only one where I get a laser alert every time.

I see those glass window boxes in our booths, up in the roof. I had my wife videotape in Nightshot mode one time as I went through a booth and the camera didn't pick up anything. Maybe that particular box wasn't operating since I wasn't going through an EZ Pass lane, but my V1 still went off.

I have more evidence that the signal is coming from overhead, based on the behavior of both a V1 and a X50 in different locations:

1. V1, visor mounted: alerts pretty consistently (9 times out of 10), as I'm starting to leave the booth. V1's view straight up is blocked by the car roof, but it could still pick up a reflection, perhaps off the hood of the car. If my sunroof is open, the rear arrow may light up as well as the front arrow.

2. X50, visor mounted: does not alert. It may not be sensitive enough to pick up a reflected signal off the hood.

3. X50, mounted @ center of windshield: alerts as I'm entering the booth. It has a clear view "up" in this location, and is further forward, so it crosses the beam or picks up the beam directly before the V1 on the visor does.

I haven't tried the V1 on the windshield, since I don't have the mount anymore, but I bet it would alert sooner, like the X50.

Also, if I use one of the leftmost exact change lanes (the ones that can be configured for either northbound or southbound traffic), many times the V1 will alert when entering the booth, and again when exiting the booth. These booths have those boxes on both ends, to accomodate traffic passing in either direction.

Also, at night, sometimes, I'll get alerts on the V1 while waiting in line to enter a booth. Probably from beams reflected off other cars.