[Hammer]

I pulled up at a traffic signal - the kind with the wires or magnets or whatever is buried in the pavement to let the traffic signal know a car is waiting. Anyway, I'm sitting there forever and nothing is happening. A truck pulls up behind me and the signal changes. So, is the Mini too light to trip the signal???

 

[cristo]

I doubt it...the mini is over 2500 pounds with most of it over the front wheels. Now, my
old '82 rabbit had a curb weight under 2000 pounds, and there is one intersection
on my way to work where the rabbit was too light to trip the signal (but the mini has
no problems at the same intersection).

 

[spf]

I understood that some lights have a sensor on the top so that if you flash your lights it triggers it.

 

[jwardell]

The rectangular cuts you see in the ground do not detect weight (It would be really, really, really expensive to put weigh scales in at an intersection). They are induction sensors, and will detect a large amount of metal over them, like a wheel or body of a car. The MINI has no problem being detected.

The optical sensors at the top of the lights sense a certain frequency flashing that is carried by emergency vehicles. If you could somehow flash your lights at the right rate and fast enough then yes it would let you through but chances are you cant, and with one flash, if it activated then it is malfunctioning.

Anyway chances are it sensed your mini but is on a delay, or waited for a break in traffic in the other direction, and just happened to change when the truck came along behind you.