Abstract: There is provided apparatus for determining the number of passengers entering and/or leaving a collective passenger vehicle. The apparatus comprises means for projecting a pair of light-beams of invisible light across the passageway of said passengers and means for receiving said light-beams. Detecting means which operate in conjunction with the light-beam receiving means are adapted to detect the energized or unenergized state of the receiving means and in response thereto to feed information to a data registering or recording means, said information being indicative of the number of passengers passing through the light-beams.