Traffic light system with daytime and night time modes - operates with increased signal light intensity for daytime visibility

摘要

The traffic lights can be switched between daytime and night-time modes in which the voltage to the signal lights is adjusted accordingly so that the intensity of the lights is increased for daytime viewing. The voltages (U, U2) are supplied from respective tap-offs of a transformer. The switching from the higher daytime voltage (U1) to the lower night-time voltage (U2) is effected via an intermediate zero voltage phase (t3..t4) the duration of which is at least one half wavelength of the AC supply.