This Standard specifies the minimum performance requirements for Variable Message Signs consistent with the improved safety of road users and defines different classes of signs and their performance requirements. It defines visual performance criteria only for Variable Message Signs subjected to lighting conditions which vary from full day-light to night-time. Signs to be used in more closely restricted ambient lighting conditions (tunnels, internal situations) are not covered. The Standard defines requirements for the visual performance, legend geometry and testing of Continuous and Discontinuous messages; and specific requirements for both retroreflective and back illuminated Continuous Variable Message Signs. Test methods are also included to assure the required levels of performance. Classification criteria are defined according to legend sizes, visual performance, change-over time and range of operating temperatures. Requirements for Discontinuous Variable Message Signs do not include distinctions between the visual technology types. No relation is defined between Variable Message Sign classes and their use.
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