The objective of this European Standard is to specify the functional safety requirements of equipment used for the control of traffic signals. It relates to the control of signals to traffic, and any associated signalled traffic movements. The primary concern is to safeguard persons and objects against hazards due to conflicting signals to traffic. The hazards to be considered include, but are not limited to, the following types of possible signal failures: a) the failure to display a red signal to traffic; b) the display of a green signal to conflicting traffic; c) the failure to display the correct signal sequence to traffic; d) the failure to provide the correct timing of all signals. Persons to be safeguarded are: a) users of traffic signals, drivers and passengers of vehicles (including public transport), pedestrians, cyclists and equestrians, persons with physical disabilities; b) maintenance and inspection personnel. This European Standard specifies the functional safety requirements for traffic signal controllers. It is applicable to traffic signal control equipment permanently and temporarily installed, but excludes portable traffic control equipment. Traffic signal controllers, as defined by this European Standard, are required to control conflicting traffic, both vehicular and pedestrian, e.g. junction signals, pedestrian crossings, shuttle signals, public transport signals, in a safe manner. The electrical safety requirements and additional traffic safety requirements, the interfacing with external equipment and the test methods for verifying compliance with this European Standard are contained in HD 638. (Author/publisher)
Abstract