You are not setting off the sensors.
Stop 1 bus or car back from the white line. See if that sets if off, if not, stop 2 bus or carloads in back of the white line.
No, it all has to do with the mass of the vehicles.You need to be dead center to trip the censors. Unless they set the sensors for a higher weight to click them.
Some places they do not want bicycles to trip them so the higher the mass needed trip it.