Laser falses on SF bridges...

[kbq]

Unit: 8500 x50

I drive the San Mateo and/or Dumbarton bridges a number of times a week, morning and evening. I usually get laser indications on each trip (I actually turn down the volume now before I hit a bridge).

Time of day doesn't seem to matter; no funny electrical issues; no accel/slowing. Can happen once or ten times, on the causeways and the elevated portions. Very infrequent that I get no hits.

It seems to be a bit less frequent in fog, but not always (this morning, for instance!).

I thought perhaps Lidar from SFO or San Jose - does the fog issue rule this out? Any other candidates?

Thanks -

Kevin

[MEM-TEK]

Hi kbq,

Welcome to the forum. Sorry nobody has replied to your post until now. Anyway, I do have a theory to answer your question:

Police LIDAR guns use pulsed infrared laser beams to measure the speed of a car. When crossing one of SF's bridges, it is possible that infrared sources such as oncoming car headlights or the sun are getting rapidly "pulsed" by the bridge's momentary cable obstructions of the source as you drive along. This is just a guess, but a few weeks ago I got a false laser alert from the sun. The sunlight was scintillating through distant bare tree branches, and this produced a false laser alert.

[FlyinZX-10R]

It could also be a laser based cruise control system from another vehicle.

[ELVATO]

Could there be maybe an airport somewhere close by, since he only gets them when he goes on the elevated parts.

[MEM-TEK]

Could there be maybe an airport somewhere close by, since he only gets them when he goes on the elevated parts.

That is a good possibility which I didn't think of.

[three]

i always get laser alerts on the dumbarton and san mateo bridges, less so on the weekends. i will even get them on some of bridges in portland, OR. i have a X50. i always wondered about what was causing this!

[hockey005]

is there a huge sign running across all lanes? liek one of those electronic ones that tell u if there is an accident or not? that could cause laser falses