AFAIK there is only 1 gatso, they can only do you if they photo the rear of the car.

We got one down here, whenever i pass it the wrong way i always knock the astra up to about 120 and stick my finger up at it so it takes the photo

Also quite entertaining to do it in rush hour, when there's people on the gatso side of the road and i go past the other way, i do about 60 to set it off... u get people wondering why it took their photo when they are at a standstill lol