Abstract: A rail mounted vehicle speed measuring device includes a first magnetic field generating member and a first magnetic field sensing member positioned at a first measuring location on the vehicle; a second magnetic field generating member and a second magnetic field sensing member positioned at a second measuring location on the vehicle, spaced a fixed distance from the first location in the direction of vehicle movement; wherein the magnetic fields generated by the first and second magnetic field generating member are influenced by the rail to produce first and second signal patterns sensed by the first and second sensing member and varying with movement of the vehicle along the rail; and device is provided for correlating the first and second sensed signal patterns to determine the time displacement between the two sensed signal patterns and the velocity of the vehicle.

Abstract: Method and device for control within a line network such as a tram line, of a number of rolling units in various line runnings, and a method for installation of said device. A number of passive position determination elements (9) such as transponders, arranged for radio scanning, are located at determined positions in the network. Control equipment (2) on board said rolling units is provided with devices (8) for scanning of the position determination elements (9) and with sensors (6) for measurement of distance travelled. The momentary unit position within the line network is determined by continuous measurement of distance travelled and by calibration of the thereby obtained position determination by scanning of successively passed position determination elements (9). Data on the design and topography of the line network is stored in a central equipment (1) and communication from the mobile units stating their positions is received in a data processing unit (4).