This European Standard specifies the functional safety requirements for traffic signal controllers. It is applicable to traffic signal control equipment permanent¬ly and temporarily installed, but excludes portable traffic control equip¬ment. 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 equip¬ment and the test methods for verifying compliance with this European Standard are contained in HD 638.NOTE National requirements may specify special conditions for public transport signals (PT) and for any other signal that is not specified in a European Standard.